List of WWII Maybach engines

In order to rationalise Germany's military vehicle production, sweeping changes were made to its entire automotive industry. The re-organisation was overseen by {{lang|de|Oberbaurat|italics=yes}} {{ill|Heinrich Ernst Kniepkamp|fr}}, head of Wa.Prüf. 6 (Weapons Inspectorate 6, responsible for tanks, armoured vehicles and motorized equipment) of the Heereswaffenamt (HWA). By late October 1935, Maybach had been designated the sole designer and manufacturer of tank and half-track engines for the entire Wehrmacht, with production later outsourced to other firms including its subsidiary Nordbau (Norddeutsche Motorenbau GmbH) in the south-eastern Berlin suburb of Niederschöneweide beside the River Spree.{{sfn|Frank|1990|p=20}}{{sfn|Milsom|1975|p=88}}{{cite web |title='Nordbau': Norddeutsche Motorenbau GmbH Niederschöneweide |website=Fotowiesel |language=de |url=https://www.fotowiesel.de/projekte/2015-bullenbahn/PICT5356 |access-date=29 November 2020 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130184750/https://www.fotowiesel.de/projekte/2015-bullenbahn/PICT5356 |url-status=live }}

Maybach AG made very few complete parts of its engines at all. Almost everything was bought in from other suppliers. Its main activity was precision machining of the castings and forgings of its own design, made by outside manufacturers, and producing complete assembled engines on a separate assembly line.{{sfn|U.S. Strategic Bombing Survey|1947|p=4}} Completely finished crankshafts were supplied by {{ill|Deutsche Edelstahlwerke AG|de}}, in Remscheid- :de:Hasten.{{sfn|U.S. Strategic Bombing Survey|1947|p=3}}{{efn|Deutsche Edelstahlwerke AG was founded in 1927 out of Vereinigte Stahlwerke as a conglomerate of high-grade and stainless steel manufacturers, including the firm of :de:Richard Lindenberg AG in Remscheid-Hasten.{{refn|Dietrich, B. (1930). Vereinigte Stahlwerke. ({{=}} Stätten deutscher Arbeit.) (In German). Berlin: Widder-Verlag, pp. 97ff.}} Using the electric Héroult-Lindenberg process, the firm produced the world's first commercial cast steel by the electric arc furnace method (electro-steel) in 1906. It swiftly began to replace crucible steel for making high-quality cast steel alloys.{{sfn|Schaffers|1910|p=813}} }} In addition, machined pistons (Mahle KG), piston rings, roller and ball bearings, fuel pumps, carburettors (Solex), and complete electrical equipment (Bosch) were acquired as finished parts from outside sources.{{sfn|U.S. Strategic Bombing Survey|1947|p=4}}

File:Bundesarchiv Bild 101I-024-3536-28, Russland, Panzer VI (Tiger I), Reparatur.jpg

Although a steady supply of spare parts is essential to an army in the field, the production of complete engines always took priority over providing spares.{{efn|{{harv|Müller-Hillebrand|1982|p=21}}. The lead author of this pamphlet, General {{ill|Burkhart Müller-Hillebrand|de}} worked in the {{ill|Operational History (German) Section|de}} of the US Army Historical Division in Karlsruhe after the war, helping to write operational histories from the German point of view.}} According to Albert Speer, Hitler himself never realised this importance: "One of his worst failings was that he simply did not understand the necessity for supplying the armies with sufficient spare parts."{{sfn|Speer|1970|pp=234–5}}{{efn|Speer continues: "This disastrous tendency was evident as early as 1942: "Presented the Führer with the monthly list of tank replacement parts and reported that despite the increase in production the demand is so high that to raise the production of spare parts we must decrease the production of new tanks." (Führerprotokoll, May 6–7, 1942, Point 38.) [...] General Guderian, the Inspector General of Tank Ordnance, frequently pointed out to me that if we could repair our tanks quickly, thanks to sufficient spare parts, we could have more available for battle, at a fraction of the cost, than by producing new ones. But Hitler insisted on the priority of new production, which would have had to be reduced by 20 percent if we made provision for such repairs.{{sfn|Speer|1970|pp=234–5}} }}

Germany never achieved the industrial capacity needed to keep its military vehicles running efficiently: when the Russian campaign got underway, the deficiencies of the armaments industry and the organisation of maintenance depots became obvious.{{sfn|Müller-Hillebrand|1982|pp=2-4}} The German armed forces suffered from continual shortages of spare parts for tanks and half-tracks until the end of the war.{{sfn|Müller-Hillebrand|1982|p=4}} When the first Tiger I tanks arrived in Russia in autumn 1942, there was only one spare engine and one transmission for every 10 tanks. A critical lack of spare parts meant that most of them were out of commission within a short period, sometimes for weeks on end.{{sfn|Müller-Hillebrand|1982|p=25}} Despite various attempts at re-organisation, friction between the distribution systems of the German Army (das Heer) and the civilian Ministry of Armaments (and from 1944 the 'Rüstungsstab') often led to confrontation and inefficiency.{{sfn|Müller-Hillebrand|1982|p=21}} Some of this can be blamed on Karl-Otto Saur of the Ministry of Armaments, whose ruthless drive for greater overall production figures tended to override the need for testing and durability concerns, and the manufacture of enough spare parts.{{sfn|Spielberger|1993b|p=23}}

According to Stieler von Heydekampf, president of the Panzer Kommission from 1943, German tank production was at a major disadvantage throughout the war because the main firms involved were heavy equipment manufacturers. It would have been more effective if the programme had been given to Ford Germany and Opel (owned by General Motors) because of their real mass production experience, but this was not done because of their American associations.{{sfn|Estes|2018|loc=Appendix I, p. 4; II, p. 11}}{{efn|Heydekampf, primarily a production man, had been manager of the Opel Truck division in Brandenburg from c1935.{{sfn|Estes|2018|loc=Appendix II, p. 3}} }}

Maybach's monopoly on engine production proved to be the bottleneck in German tank production.{{sfn|U.S. Strategic Bombing Survey|1947|pp=3, 11}}{{sfn|Halder|1947|p=115 [pdf 561]}} From 1942, after the German invasion of the Soviet Union, Maybach started dispersing its manufacturing activities, licensing eight other firms to manufacture its engines. Adler Werke in Frankfurt/Main built the HL42 from January 1942; Saurer Werke in Vienna, Krauss-Maffei (Munich), and Borgward in Bremen were licensed to build the HL62 & HL64; Maschinenfabrik Bahn Bedarf (MBB) in Nordhausen made the HL109, and also the HL120—along with Maybach's subsidiary Nordbau in Berlin and MAN in Nurnberg; and Auto Union in Chemnitz (Siegmar Werke) made HL230s, having tooled up from October 1943–March 1944.{{sfn|U.S. Strategic Bombing Survey|1947|pp=9–10}} Henschel & Sohn in Kassel made large quantities of major components for Maybach in 1943–1944: 2,434 crankshafts, 1,850 crank cases, 32,121 connecting rods and 8,196 'closing covers' (undefined - maybe valve covers or possibly cylinder heads).{{sfn|USSBS Report No. 85|1947|loc= Exhibit D, [p. 44]}}

Maybach from August 1943 also organised 11 of its own dispersal machining sites located from a few miles away to some 60 miles distant; the finished parts were then sent to a designated factory for assembly. These precautions allowed manufacture of complete engines to take place away from Friedrichshafen.{{sfn|U.S. Strategic Bombing Survey|1947|pp=8–9}} On Hitler's orders in March 1944, the extensive cellars below the town of Leitmeritz (now Litoměřice, Czech Republic) on the river Elbe were to be used for the anticipated assembly for HL120 and HL230 tank engines, in case a manufacturing plant were to be bombed.{{sfn|Spielberger|1993b|p=141}}

Despite these precautions, by late 1943 there was still a severe shortage of spare tank engines.{{efn|For example, an official report in September 1943 on the state of various battalions under the command of Panzerjäger-Regiment 656 (including the 653rd Heavy Panzerjäger Battalion) stated that sixty complete HL120 engines (two per tank) were needed to bring the Ferdinand battalions up to strength.{{harv|Munch|2005|pp=62–3}} In a long list of other modifications, only two related to the engine: the fuel line needed shielding from the exhaust; and oil leaked onto the fan housing, both leading to fires in the engine compartment.{{harv|Munch|2005|p=64}} A total of only 91 Ferdinands were ever built.}} Rather than concentrate on proven designs, Maybach continued to bring out new, relatively untested models; the wide variety of engine types seriously hampered efforts to fix the multiple defects which Maybach engines developed under combat conditions.{{sfn|Müller-Hillebrand|1982|p=25}} The extreme difficulty of stocking so many spares at the front, several thousand kilometres away from the factory, swiftly led to vehicles being unserviceable for combat. Because the armaments industry was already working at full capacity, it was not possible to completely replace obsolete models with new versions. Instead, the number of tank models and types within each series issued to the field forces increased steadily, which only made the maintenance and repair situation worse.{{sfn|Müller-Hillebrand|1982|p=3}}

Severely damaged tanks from the Russian front were initially shipped back to Germany, or to the Nibelungenwerk or the Vienna Arsenal for repair;{{sfn|Müller-Hillebrand|1982|p=28}}{{sfn|Munch|2005|p=172, 187}}{{cite web |last=Ankerstjerne |first=Christian |title=Homeland Armor Maintenance |website=Panzerworld |date=9 April 2016 |url=https://panzerworld.com/homeland-armor-maintenance |access-date=16 May 2020 |archive-date=14 January 2019 |archive-url=https://web.archive.org/web/20190114140420/https://panzerworld.com/homeland-armor-maintenance |url-status=live }} but the prospect of inevitable delays often meant that vehicles were instead cannibalised at the front for parts. Often when a new engine was delivered, there was little left except the hull of the tank it was intended for.{{sfn|Müller-Hillebrand|1982|pp=19, 25}} Nevertheless, the maintenance crews did their best, often retrieving knocked-out tanks under considerable difficulties.{{efn|For example, up to five 18-ton Sd.Kfz. 9s were needed to haul an immobilised Ferdinand through the mire of the Eastern Front.{{sfn|Munch|2005|pp=138-9}} }}

As the war progressed, new Maybach engines tended to be rushed into production, without adequate testing and improvement. As a result, they were viewed as unreliable (although this would be expected of any un-developed engine).{{sfn|Milsom|1975|p=9}}{{efn|Heinz Guderian, General-inspekteur der Panzertruppen, made an even-handed report about the Panther in July 1943 after Operation Citadel:

:"The fact that the Panther appeared for the first time on the battlefield focused general interest. Comparisons against losses of other Panzer units were not made. Therefore the high command and troops quickly jumped to the conclusion: The Panther is worthless!

:"In closing, it should be remarked that the Panther has been proven successful in combat. The high number of mechanical breakdowns that occurred should have been expected since lengthy troop trials have still not been accomplished. The curve of operational Panthers is on the rise. After the deficiencies in the fuel pumps and the motors are corrected, the mechanical breakdowns should remain within normal limits. Without consideration of our own mistakes, the disproportionately high number of losses through enemy action attests to especially heavy combat."{{sfn|Jentz|1996|p=99}} }} All the 325 new Panther tanks delivered to Russia in early 1943 had to be returned because of serious defects in the steering;{{sfn|Müller-Hillebrand|1982|pp=24-25}} they were underpowered by the HL210 P30 engine, and its replacement, the HL230 P30 (which didn't arrive until late 1943) suffered from over-heating, fires in the engine compartment and blown gaskets.{{sfn|Jentz|1995|pp=61–62}}

By way of comparison, the Soviet Army used a single basic engine (the V-12 diesel Kharkiv V-2) to power the majority of its tanks – with a few modifications – starting with the BT-7M and its successor the T-34,{{sfn|Müller-Hillebrand|1982|p=43}} producing {{convert|500|hp|abbr=on}} @ 1800 rpm in 1939;{{sfn|Hughes|Mann|1999|p=34}} the SU-85 and SU-100; the KV-1 and KV-2 (600 hp with supercharging in 1939); and the IS-2, ISU-122 and ISU-152 and the T-10. Maybach didn't produce a more powerful acceptable engine until late 1943 with the HL230 P30.

Starting in March 1944, a series of Allied precision and area bombing raids put the Maybach factory out of action for several months. Those of 27/28 April and 20 July especially inflicted heavy damage on the plant.{{sfn|U.S. Strategic Bombing Survey|1947|pp=5–6}} However, engine production continued at the various dispersed machining sites and manufacturers. If the various firms making Maybach motors under license had not been in a position to continue producing engines, the German Army's entire tank program would have been seriously jeopardised.{{sfn|U.S. Strategic Bombing Survey|1947|pp=3–4}}

Although the German Army used various combat vehicles appropriated from other countries, they continued to be powered by their original engines. Maybach engines were fitted to the German fighting vehicles for which they had been designed.{{efn|An exception is the Ferdinand tank hunter, originally a petrol-electric design by Ferdinand Porsche, intended to be powered by two Porsche Typ 101 15-litre gasoline V-10 air-cooled engines each developing 310 PS driving electrical generators and motors. The Porsche motors never worked satisfactorily, and two over-stressed, over-heated, HL120 engines were used instead.}}

All Maybach engines for AFVs which reached series production were gasoline four-stroke water-cooled designs. The firm's managing director, Dr. Karl Maybach (son of the founder Wilhelm Maybach), had stated that "he was born water cooled and wanted to die water cooled."{{sfn|Estes|2018|loc=Appendix III, p. 4}}{{efn|Maybach also had considerable experience in designing and manufacturing diesel engines. The enormous pre-war French Char 2C used two Maybach 12-cylinder diesel engines of 250 PS (186.5 kW), originally installed in Zeppelin airships.{{cite web |title=Char 2C |last=Janusas |first=Christopher |website=The Online Tank Museum |date=5 June 2021 |url=https://tanks-encyclopedia.com/ww2/france/fcm-2c.php#comments |access-date=8 August 2023}} Maybach designed a series of diesel engines for railroad locomotives, beginning in 1924 with the 'G4a' 6‑cylinder diesel engine producing 150 hp at 1,300 rpm, fitted in a railcar by Eisenbahn Verkehrs AG Wismar (EVA). This was followed in 1932 by the Karl Maybach-designed diesel 'GO5' motor, a V-12 railcar drive of 400 hp, two of which powered the SVT 877, the 'Flying Hamburger'. The post-war GTO6 and GTO6a V-12 diesel engines powered the DB Class V 60 shunters, and the 'MD' series drove the {{ill|DB-Baureihe VT 08|de}} series.{{cite web |title=High-Performance Maybach Locomotive-Engines – An International Export Hit Made In Friedrichshafen |last=Henningsen |first=Fabian |date=31 October 2022 |url=https://maybach.org/high-performance-maybach-locomotive-engines-an-international-export-hit-made-in-friedrichshafen/ |website=Maybach Foundation |access-date=7 August 2023}} }}

Before the war the fuel industry had indicated that petroleum was going to be easier to produce than synthetic diesel, and development of gasoline engines was therefore favoured. By around 1943 the situation had turned around, but by then it was too late to change.{{sfn|Estes|2018|loc=Appendix II, p. 7, III p. 3}} Dr. Ferdinand Porsche had consistently pushed for air-cooled diesels, but his organisation's designs never functioned satisfactorily.{{sfn|Estes|2018|loc=Appendix I, p. 5}} The twin large Porsche gasoline V-10 engines slated for the Tiger (P) never worked satisfactorily, and two over-worked Maybach HL120s were fitted instead to drive the electric generators and final drive motors in the subsequent Ferdinand.{{sfn|Estes|2018|loc=Appendix II, p. 8}}

A number of Maybach motors shared the same basic design but had different engine sizes, the larger engines having bigger cylinders to increase the capacity. Similar engine designs had shared parts lists, e.g. the NL38 and HL42; the HL57 and HL62; and the HL108 and HL120.Photos of various front covers at {{cite web |title=Maybach HL 62 TUK 6-cylinder Vergasermotor Owner's Manual Brochure |url=https://www.classicseller.com/en/various/engine-gear/maybach-hl-62-tuk-6-cylinder-vergasermotor-owner-s-manual-brochure-101278 |website=classicseller.com |access-date=20 May 2018 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130184753/https://www.classicseller.com/i/101278/various/maybach-hl-62-tuk-6-cylinder-vergasermotor-owner-s-manual-brochure |url-status=live }}

The 6-cylinder Maybach engines used a single Solex 40 JFF II down-draught ({{langx|de|Fallstrom}}) carburetor, and earlier V-12s used two.Photos of Solex 40 carbs (end of page) at {{cite web |url=http://www.rommelkiste.de/panzer4/bilder.html |title=Panzer IV Ausf.G (früh) |website=Rommelkiste.de |language=de |access-date=20 April 2018 |archive-date=15 May 2017 |archive-url=https://web.archive.org/web/20170515061254/http://www.rommelkiste.de/panzer4/bilder.html |url-status=live }} Later V-12s used Solex 52 JFFs.

A hand-cranked inertia starter (Schwungkraftanlasser) was fitted to the V-12 engines to supplement the Bosch 24V electric starter motor (powered by two 12V batteries) in cold weather.Illustration in {{harvnb|Koch|2000|p=27}}.

Maybach used a series of letter codes and numbers to identify specific engine models, namely:

• NL / HL – performance
• TU / TR – lubrication
• K – clutch
• R / RR – V-belt drive for compressor and/or radiator fans
• M – "schnapper"-type magneto ignition

Although these codes usually indicate what ancillary equipment was fitted at the factory (e.g. the HL42 TUKRRM and the HL57 TR), there are some exceptions, discussed below.

The individual engine number and its capacity, the model type, and year of manufacture are hand-stamped on each crankcase. On 6-cylinder models with schnapper magneto ignition, this information is found on the magneto housing: e.g.{{cite AV media |title=Maybach HL42 TUKRM engine number |url=http://fahrzeuge-der-wehrmacht.de/Bilder/Maybach_HL-42_Mu_04-1.jpg |website=Fahrzeuge der Wehrmacht |language=de |access-date=21 May 2018}} Photo hosted at [http://fahrzeuge-der-wehrmacht.de Fahrzeuge der Wehrmacht] {{Webarchive|url=https://web.archive.org/web/20210130184816/http://fahrzeuge-der-wehrmacht.de/ |date=2021-01-30 }}.

MOTOR Nr 730192

1943

And on the HL210, stamped at the top end of the crankcase above the flywheel cover: {{sfn|Lloyd|Balkwill|Johnston|2008|pp=166–7}}

Mot. Nr. 46302

HL210{{spaces|6}}P45

• NL = Normalleistung (normal performance motor)
• HL = Hochleistung (high performance motor)

This is followed (without space) by the approximate engine capacity (e.g. HL42 = approx. 4.2 litres.)

Compared to the NL motors, the HL (high performance) series had a higher compression ratio, which increased the power output. This advantage was somewhat lost when a mandatory requirement to run on lower-quality OZ 74 (74 octane) gasoline after October 1938 necessitated the compression ratio of the HL series to be lowered, achieved by fitting shorter pistons and a new cylinder head.{{sfn|Jentz|Doyle|Friedli|2013|p=22-4–70}} This may partially explain the similar power outputs of engines with different capacities, shown in the table further below.

• TR = Trockensumpfschmierung (dry sump lubrication), generally fitted to tanks - because of low ground clearance - and to the Sd.Kfz. 10 and 250 half-tracks. There is no sump{{dn|date=June 2025}} below the crankcase: the engine oil is contained in a reservoir on one side. On later V-12s there is a tunnel through the oil reservoir, through which the hand crank for the inertia starter passes, operated from the outside rear of the vehicle.

::In a number of cases, especially the dry sump tank engines (e.g. the HL108 TR), this is the complete designation of an engine: in other words, there is no factory-fitted clutch (K) attached to the engine; no extra drive belts driving a compressor (R) and/or dual fans (RR) on custom pulleys; ignition is achieved by a magneto driven off the camshaft ({{lang|de|Steuerwelle}}) rather fitted in its own housing (M) ({{lang|de|Schnapper-magnetzündung}}); and no specific vehicular installation (P, S, or Z) is implied.

• TU = Tiefer Unterteil ('deep lower part' i.e. wet sump), only fitted to some half-tracks. The sump generally has an inverted triangle shape, bolted to the underneath of the crankcase housing.

::Most of the TU (wet sump) type engines were installed in half-track artillery tractors Sd.Kfz 6, 7, 8, 9 and 11, and were fitted with some or all of the ancillaries (K, R, or M). There appear, nevertheless, to be exceptions. For example, the HL57 TU was apparently only installed in some versions of the Sd.Kfz. 7, which was in fact fitted with a factory clutch, integral compressor and magneto. The extra equipment was fitted as standard and the extra letter codes were not included in the model number.{{efn|Likewise, the bored-out HL62 TUK engines were also only fitted in some variants of the Sd.Kfz. 7; on these motors the compressor was an integral design part of the engine, and not an ancillary (R) which is thus excluded from the model designation. See also § Compressor. }}

In addition, 'T' by itself has no meaning; it is always directly followed by either R or U, but 'R' in this position should not be confused with an (R) signifying a V-belt drive for a compressor (see below). Furthermore, in some sources engines may be referred to simply as e.g. "a Maybach HL 120 of 300 metric horsepower",{{citation needed|date=May 2020}} which indicates that further information is needed to identify the particular model number.

• K = Kupplung or Kupplungsgehäuse (clutch housing): a clutch is attached directly to the flywheel end of the crankshaft, generally driving a manual gearbox with 4 forward speeds and 1 reverse, plus a high/low reduction gearbox, giving 8 forward and 2 reverse ratios (4+1 x2). This type of transmission was fitted to all the half-tracks with a TU-type engine, and to early Panzer Is. The transmission could also have a rear power take-off (PTO) shaft fitted to power a winch; or turntables for either a gun, or crane on e.g. the Sd.Kfz. 9/1.See Lubrication chart and photos of the model build at [http://panzerserra.blogspot.com/2013/02/famo-schwerer-zugkraftwagen-18-t-sdkfz.html FAMO - Schwerer Zugkraftwagen 18 t - SdKfz 9 - Crane and cargo version] {{Webarchive|url=https://web.archive.org/web/20191127015959/http://panzerserra.blogspot.com/2013/02/famo-schwerer-zugkraftwagen-18-t-sdkfz.html |date=2019-11-27 }} by Panzerserra, retrieved 10 December 2019. The Sd.Kfz. 10 had a unique arrangement with a conventional clutch attached to the engine driving a pre-selector Maybach 'Variorex' VG 102 128H gearbox. See also § Compressor below.

File:Pz_III_Motor-Getriebe.svg HL120 TRM engine and Maybach-Variorex SRG 32 8 145 pre-selector gearbox, fitted to Ausf. E–G (in German). Click picture for English translation.]]

• If there is no factory-fitted clutch (K), this indicates a tank engine (except early Panzer Is and later Panzer IIIs).{{efn|The HL120 TRM was in fact fitted with a clutch in the Panzer III Ausf. H onwards,{{sfn|Jentz|Doyle|2007a|pp=70–71}} but the designation 'HL120 TRMK ' seems not to have been used.

The ZF SSG 76 and 77 gearboxes (both supplied with a clutch) were installed in the pre-production Panzer III Ausf. A–D{{sfn|Perrett|1980|p=5}} and the Ausf. H–N respectively.{{sfn|Koch|2000|p=20}}{{sfn|Perrett|1980|pp=6–9}} Between these two series, the ill-fated semi-automatic Maybach SRG 32 8 145 was used in the Panzer III Ausf. E–G. Maybach's own modified clutch was fitted at the factory as a option: and thus the Maybach HL108 TR and HL120 TRM engines (which differed between the Panzer III and Panzer IV tanks) could be ordered from the manufacturer with or without a clutch, depending on the gearbox.{{cite web |title="478. WH Dienstvorschrift Maybach HL 120 TRM Ersatzteilliste \ Wehrmacht Manual: Maybach HL 120 TRM spare parts list" |url=https://bushmakow.com/library-cat/maybach-motoren/ |via=Bushmakow.com |publisher=Maybach Motoren |place=Friedrichshafen |series=Nm 261/237 5.43.25 |access-date=16 March 2025 |quote=On title page: Beachten: Ausführung "A" oder Ausführung "B".}}{{cite web |title=487. Heft 90 D Maybach HL 108-120 TR TRM Panzer |url=https://bushmakow.com/library/487-heft-90-d-maybach-hl-108-120-tr-trm-panzer/ |via=bushmakow.com |access-date=5 October 2004}}
Official Memorandum including engine parts list; Appendix [pdf 35] listing all the different engine parts to be supplied for each Ausf. of all Panzer III and IV tanks; and illustrations [pdf 43].

See also HL120 TRM in Table 1}} Instead, a horizontal cardan shaft connects the flywheel to a separate gearbox next to the driver. This could be a pneumatically controlled, pre-selector Maybach-Variorex (e.g. certain Panzer IIIs and Stug III); or a synchromesh ZF 'Aphon' (e.g. later Panzer III and IVs); or a hydraulically controlled Maybach-Olvar (e.g. Tiger I and II).

• A 10-speed Maybach-Variorex SRG 32 8 145 gearbox{{efn|SRG {{=}} {{lang|de|Schaltreglergetriebe}}, 'shift regulator [or controller] gearbox'. Maybach changed the name from SRG to Variorex in 1939. {{harv|Spielberger|1994|p=37}}.}} was fitted in Panzer IIIs Ausf. E–G,{{sfn|Koch|2000|p=20}} operated by vacuum pressure generated by a compressor (R) - see next section. The main clutch is integral to the gearbox housing.Photos, diagrams (some in English) and explanations here: {{cite web |url=https://kedoki.livejournal.com/100805.html |title=О крайней упоротости Pz.III ausf.E-G. Почему Pz.III ausf.E-G упороты (Flaws in the Panzer III ausf. E-G) |website=Kedoki |language=ru |access-date=21 April 2018 |archive-date=19 February 2018 |archive-url=https://web.archive.org/web/20180219020040/http://kedoki.livejournal.com/100805.html |url-status=live }} (Russian website, but machine translation is not too bad these days). (See also diagram on right.)
• Other tank gearboxes included the synchromesh ZF Aphon SSG{{efn|SSG {{=}}{{lang|de|Synchronisiert Sechsgang Getriebe}}, 'synchronised six-speed gearbox'{{sfn|Jentz|Doyle|2006|p=3-50}} }} 5x and 7x series gearboxes (the SSG 75 fitted in early Panzer IV had five forward gears and one reverse:{{sfn|Perrett|1999|p=5}} the 76 and 77 had six forward and one reverse). The main clutch ({{lang|de|Hauptkupplung}}) (LA 120 HD) was bolted to the gearbox on the SSG 75, and incorporated into the main housing in the 77.{{sfn|Spielberger|1994|loc=diagrams p.36; 40}} The SSG 77 gearbox replaced the mechanically vulnerable Variorex in the Stug. III Ausf. C.{{sfn|Anderson|2016|p=25}}{{sfn|Spielberger|1994|p=40}} Bigger tank engines (e.g. the HL230) used a hydraulically controlled Maybach-Olvar gearbox such as the Olvar OG 40 12 16 (8 forward gears, 4 reverse), fitted to Tiger Is and IIs.{{sfn|Jentz|Doyle|2000b|p=32}}Photos at {{cite web |title=Tiger II Maybach Olvar EG 401216 B transmission unit |website=stalker6delta.tumblr.com |url=https://stalker6delta.tumblr.com/post/159962486191/the-tiger-iis-maybach-olvar-eg-401216-b |access-date=17 July 2019 |archive-date=18 July 2019 |archive-url=https://web.archive.org/web/20190718191804/https://stalker6delta.tumblr.com/post/159962486191/the-tiger-iis-maybach-olvar-eg-401216-b |url-status=live }}Diagrams and explanations here: {{cite web |last=Hamby |first=Alan |title=Transmission & Steering |website=Tiger I Information Centre |access-date=11 May 2020 |url=http://www.alanhamby.com/transmission.shtml |archive-date=4 June 2020 |archive-url=https://web.archive.org/web/20200604052704/http://www.alanhamby.com/transmission.shtml |url-status=live }}
• Some half-track gearboxes also included a power take-off shaft (PTO) driving an external winch ({{langx|de|Seilwinde}}).{{efn|Diagram of Sd.Kfz. 9 geartrain at {{harvnb|Spielberger|1994|p=215}}. Key, from r.: {{lang|de|Seilwinde}} – winch; {{lang|de|Untersetzergetriebe}} – reduction gearbox; {{lang|de|Gleiskette}} – track; {{lang|de|Bremszylinder}} – [air]brake cylinder; {{lang|de|Lenkbremse}} – steering brake; {{lang|de|Lenkgetriebe}} – steering gear; {{lang|de|Kupplung}} – clutch; {{lang|de|Luftfilter}} – air filter; {{lang|de|Triebrad}} – driving wheel; {{lang|de|Fahrbremse}} – road brakes; {{lang|de|Triebradenantrieb}} – drivewheel gearbox; {{lang|de|Wechselgetriebe}} – change speed gearbox.}}

• R = Riemenantrieb für Luftpresser (V-belt drive for air compressor), driven at the radiator end by a pulley with an extra groove. Most of the half-track engines had a compressor fitted, to power various types of equipment (discussed below).

On some engines (e.g. the NL38 TUK) the compressor was an integral part of the engine, driven by internal gears and mounted on top of the cam cover at the flywheel end. The compressor is not specifically indicated in the model number. In similar fashion, on the HL 57 TU and 62 TUK the compressor was located in a gear-driven housing next to the clutch on the inlet side.{{refn|Photo of HL62 TUK at {{harvnb|Spielberger|1993|p=67}} }}

On other models, the compressor was an external belt-driven ancillary denoted by an (R) in the model number (e.g. HL38 TUKR), it was mounted on one or other side of the engine, driven by an extra V-belt at the radiator end. Thus the lack of an (R) in the model number doesn't necessarily mean that a compressor wasn't fitted. The compressor was used to power various types of equipment, including:

:*Sd.Kfz. 10 and 250 – Variorex VG 10 2 128H pre-selector gearbox

:*Sd.Kfz. 11 and 251 – air brakes on towed equipment (e.g. Pak 40 anti-tank gun)

:*Sd.Kfz. 6–9 – pneumatic foot/parking brake + towed equipmentMany detailed photos at {{cite web |title=Sd.Kfz. 6/2 with 37mm Flak 36: air brake details |first=Ron |last=Lebert |website=Missing-Lynx |url=https://www.tapatalk.com/groups/missinglynx/sd-kfz-6-2-with-37mm-flak-36-t321481-s100.html |access-date=11 May 2020 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130184752/https://www.tapatalk.com/groups/missinglynx/sd-kfz-6-2-with-37mm-flak-36-t321481-s100.html |url-status=live }} (e.g. 15 cm sIG 33 towed by the Sd.Kfz 7{{cite web |website=Panzerserra Bunker |title=15 cm sFH 18 German field howitzer |date=10 March 2017 |url=http://panzerserra.blogspot.com/2017/03/15-cm-sfh-18-german-field-howitzer.html |access-date=12 May 2020 |archive-date=7 February 2020 |archive-url=https://web.archive.org/web/20200207233043/http://panzerserra.blogspot.com/2017/03/15-cm-sfh-18-german-field-howitzer.html |url-status=live }})

:*Panzer III Ausf. E–G, and Stug III Ausf. A (only 20 made)§ – Maybach Variorex SRG 32 8 145 pre-selector gearbox

::On certain Panzer IIIs, and Stug III, and on the Sd.Kfz. 10 with its derivative the Sd.Kfz. 250, the compressor provided the (reverse) pressure for a pneumatically operated pre-selector gearbox. The air inlet of the compressor is connected to the system, not the outlet: the compressor works "in reverse" to create a vacuum. To shift gears, the pre-selector lever is set in the desired position or slot, and when the next gear is needed, the clutch pedal is depressed for about one second. This opens a valve inside the Variorex gearbox, which operates specific vacuum-actuated pistons attached to selector forks: these move dog clutches, which select the desired gearing. After about one second the driver releases the clutch pedal with the desired gear semi-automatically engaged with minimum effort on the driver's part.

• KR = Clutch and compressor: production versions of the Demag half-tracks, the Sd.Kfz. 10 (manufacturer type D7) and Sd.Kfz. 250 (D7p) were fitted with a Maybach SRG semi-automatic gearbox, type VG 10 2 128H,{{efn|VG {{=}} {{lang|de|Variorex-Getriebe}}, 'Variorex gearbox'; H {{=}} {{lang|de|Hohlwelle}} ('hollow shaft', NB not Hohlachse), [ie 'Power Take-Off', PTO] for "providing power to auxiliary equipment for spreaders and compressors of Sd.Kfz. 10/2 ({{lang|de|Entgiftungskw.}}, 'chemical decontaminators') and Sd.Kfz. 10/3 {{lang|de|Spruehkw.}} ('poison gas sprayers').{{cite web

|last=Dorn

|first=Johannes

|date=27 July 2022

|title=Leichter und Mittlerer Entgiftungskraftwagen (Sd.Kfz.10/2 and Sd.Kfz.11/2)

|url=https://tanks-encyclopedia.com/sdkfz-10-2-and-sdkfz-11-2/

|access-date=5 September 2023 }} }} with 7 forward and 3 reverse gears.{{cite book |chapter=Comparative table of various types of German half-tracked vehicles |title=TM-E 30-451: Handbook on German Military Forces |chapter-url=https://www.lonesentry.com/manuals/tme30/ch8sec2figure6.html |year=1945 |publisher=U.S. War Department |series=(Online version hosted at LoneSentry.com) |access-date=11 May 2020 |archive-date=6 December 2019 |archive-url=https://web.archive.org/web/20191206022414/http://www.lonesentry.com/manuals/tme30/ch8sec2figure6.html |url-status=live }}{{sfn|Jentz|Doyle|2008b|p=3}}{{sfn|Jentz|Doyle|2009|pp=8, 20}}
Although they worked on the same vacuum principle as the bigger tank pre-selector gearboxes (e.g. Variorex SRG 32 8 145, installed in Panzer III Ausf. E-G), these gearbox types had no integral clutch, and were much smaller than those fitted to tanks. The drive passed through a standard clutch attached to the engine via a cardan shaft into the gearbox: depressing and releasing the clutch pedal simultaneously disengaged the main clutch and actuated the vacuum pistons to engage the pre-selected gear ratio.Good cutaway diagram here: {{cite web |url=https://warspot.ru/15562-avtostradnye-tanki-po-nemetski |title=Автострадные танки... по-немецки |trans-title=Avtostradnye tanki... po-nemetski |language=ru |website=Warspot.ru |access-date=11 May 2020 |url-status=dead |archive-date=3 August 2020 |archive-url=https://web.archive.org/web/20200803182629/https://warspot.ru/15562-avtostradnye-tanki-po-nemetski }}{{sfn|Milsom|1975|p=10}}Photos at {{cite web |last=Schwabe |first=W. |title=Surviving SdKfz.10 D7 Demag Half-Tracks |date=30 December 2019 |url=http://the.shadock.free.fr/Surviving_SdKfz10.pdf |access-date=11 May 2020 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130184752/http://the.shadock.free.fr/Surviving_SdKfz10.pdf |url-status=live }} and {{cite web |last=Schwabe |first=W. |title=Surviving SdKfz. 250 Half-Tracks |date=15 January 2020 |url=http://the.shadock.free.fr/Surviving_Sdkfz_250.pdf |access-date=11 May 2020 |archive-date=26 November 2020 |archive-url=https://web.archive.org/web/20201126124208/http://the.shadock.free.fr/Surviving_Sdkfz_250.pdf |url-status=live }} (search both for MM Park, La Wantzenau)

• KRR = Clutch, compressor, and extra belt drives for radiator fans: fitted to a number of Sd.Kfz. 251 variants, which had a different radiator from the unarmored Sd.Kfz. 11 on which it was based.{{sfn|Jentz|Doyle|2005|p=15-2-2}}
  A triple V-belt pulley mounted at the top of the engine also drove the twin cooling fans mounted directly between the engine and the radiator.{{cite web |url=https://www.perthmilitarymodelling.com/reviews/vehicles/greatwall/gw_l3518.html |title=German WWII Maybach HL 42 TUKRM Engine |first=Terry |last=Ashley |website=PMMS |access-date=11 May 2020 |archive-date=7 November 2012 |archive-url=https://web.archive.org/web/20121107161332/http://perthmilitarymodelling.com/reviews/vehicles/greatwall/gw_l3518.html |url-status=live }}{{efn|1="Cette motorisation est redésignée avec une lettre R supplémentaire (R = ventilation séparée), donnant ainsi les NL38 TUKRR, NL38 TUKRRM et HL42 TUKRRM."{{cite journal |first=Nicolas |last=Couderc |journal=Véhicules Militaires Magazine |issue=32 |date=April–May 2010 |pages=18–19 |title=Les Sd.Kfz.251 Ausf. A, B, C et D |language=fr |url=http://fr.1001mags.com/parution/vehicules-militaires-magazine/numero-32-avr-mai-2010/page-18-19-texte-integral |access-date=11 May 2020 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130184806/http://fr.1001mags.com/parution/vehicules-militaires-magazine/numero-32-avr-mai-2010/page-18-19-texte-integral |url-status=live }} This roughly translates as 'separate (or forced) ventilation', Fremdbelüftung.}}

All Maybach engines used a Bosch 12-volt magneto for the ignition. There were two main types:

• Driven off the camshaft ({{lang|de|Steuerwelle}}) (or the camshaft pinion), located at the top of the engine at the flywheel end. This type of magneto can often be identified at the top of the engine at the flywheel end by a circular, slightly domed cover, and a tubular duct (sometimes corrugated) which fed the ignition leads out of sight behind an engine cover plate. This type of installation ({{lang|de|Steuerwelle-Magnetzündung}}) was part of the standard specification and not included in the model letters (e.g.HL98 TUK). This applies to some 6-cylinder modelsPhoto at {{cite web |title=Maybach NL-38 |url=http://www.fahrzeuge-der-wehrmacht.de/Bilder/Maybach_NL-38_Ko_01-1.jpg |website=Fahrzeuge der Wehrmacht |language=de |access-date=21 May 2018 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130184754/http://www.fahrzeuge-der-wehrmacht.de/Bilder/Maybach_NL-38_Ko_01-1.jpg |url-status=live }} and some V-12s.{{refn|Photo of damaged HL120 TRM Ausführung "B": {{harvnb|Koch|2000|p=18}} }} On the HL210 the magnetos are separately located above the ends of the camshafts, and on the HL230 they are centrally installed between the cylinder heads.
• M = {{lang|de|Schnapper-Magnetzündung}} (impulse magneto ignition).{{efn|With the low starting speed of the engine (e.g. by hand or with a slow-running starter), a magneto ignition system would generate only a very weak or no ignition spark. The magneto is equipped with a spring mechanism that additionally accelerates the rotor at low speeds and retards the ignition spark.Kroes, Michael (1995). Aircraft Powerplants. New York: Glencoe. p. 180. The English name of this device is impulse coupling; in German it is usually referred to as a snapper ({{lang|de|Schnapper|italics=yes}}), derived from the snapping sound that these magneto ignitions generate when the device is triggered.{{cite journal |language=German |url=https://www.aerokurier.de/praxis/know-how/magnetzuendsysteme/695580 |first=Mark |last=Juhrig |title= Magnetzündsysteme |journal=Aerokurier |issue=8/2016 |date=2016 |access-date= 22 June 2021}}}} Some 6-cylinder models had this type of magneto in its own housing on the right-hand side, and driven off the starter ring on the flywheel.Photo (with Solex carburetter above, and fuel pump below l.) at {{cite web|url=https://www.flickr.com/photos/pilot_michael/15789565002|title=Maybach Sechszylindermotor HL 42|website=flickr|date=11 November 2014|access-date=20 April 2018|archive-date=30 January 2021|archive-url=https://web.archive.org/web/20210130184755/https://www.flickr.com/photos/pilot_michael/15789565002|url-status=live}} In V-12s, the magneto is located in the V of the cylinder block, driven off the camshaft pinion. This type of installation is indicated with an (M) in the model number, e.g. HL42 TUKRM, HL120 TRM.{{efn|Photos of both types can be seen at {{cite web|url=http://fahrzeuge-der-wehrmacht.de/Artikel/Motoren.html |title=Maybach Motoren |website=Fahrzeuge der Wehrmacht |access-date=14 December 2021}}, e.g. NL38 TR and HL54 TUKRM. }}

::A number of engines of the same basic design were first fitted with the camshaft-driven ({{lang|de|Steuerwelle}}) type and later with the {{lang|de|Schnapper}} type (e.g. HL62 TR/TRM, HL120 TR/TRM). The HL120 TR used two Steuerwellen Magnetzündern,{{sfn|Jentz|Doyle|2007a|p=3-2-8}} and the later HL120 TRM Ausführung "A" used in the Panzer III and Stug III used a single schnapper-type magneto serving all 12 cylinders, located in the V of the cylinder block at the radiator end.{{sfn|Jentz|Doyle|2007a|pp=3-2-15, 16}}{{cite book

|title=Panzerkampfwagen III Ausführung E bis L...Vorläufige Instandsetzungsanleitung für den Motor vom 3.11.43

|trans-title=Panzer III Mark E to L...Preliminary Repair Instructions for the engine

|series=Manual D 652/50c

|language=de

|date=November 1943

|pages=47-50 [pdf 25–27]

|via=Bushmakow.com

|url= https://bushmakow.com/library/62-d-652_50c-panzerkampfwagen-iii-u-panzerbefehlswagen-ausf-e-l-gepanzerte-selbstfahrlafette-ausf-a-g-f-sturmgeschuetz-7-5cm-kanone-motor-1943-03-01/}}

Most models were also fitted with a belt-driven Bosch generator for charging the two 12-volt batteries for the 24-volt electric starter motor; and for 12-volt lighting, etc. On 4- and 6-cylinder engines the generator was usually connected by a short drive shaft to the separate belt-driven coolant pump, located close to the cylindrical oil cooler.

• P = Panzerkampfwageneinbau (tank installation?){{citation needed|date=February 2020}}
• Z = Zerstörereinbau (tank destroyer installation?){{citation needed|date=February 2020}}
• S = Schleppereinbau (military tractor installation?){{efn|One of the few engines with an (S) in its designation is the HL42 TRKMS. According to Jentz and Doyle, they were specially designed for the schwerer Wehrmachtschlepper (s.Ws), the successor to the Sd.Kfz. 5. The engines were built only by Auto Union.{{sfn|Jentz|Doyle|2010b|p=22-3-38}} }}

These letters were only used on some models, e.g. HL42 TRKMS, HL45 Z, HL157 P.

The HL230 P30 and P45 appear to fall into this category, being named according to their original project specification: the HL230 P30 was designed to be fitted in the Panther, whose prototype was the 30-ton class VK30.02; and the HL230 P45 went in the Tiger, whose final 45-ton class prototype was numbered VK45.01.{{cite web |title=Which vehicles used the Maybach SHL 66 petrol engine? |website=Axis History Forum |url=https://forum.axishistory.com/viewtopic.php?t=132726 |access-date=16 May 2020 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130184759/https://forum.axishistory.com/viewtopic.php?t=132726 |url-status=live }}

• NL38 TRKM = Normal performance 3.8 litre, dry sump, clutch, schnapper magneto (Panzer I Ausf. B)
• HL42 TUKRRM = High performance 4.2 litres, wet sump, clutch, belt-driven compressor, twin radiator fans, schnapper magneto (Sd.Kfz. 251)
• HL62 TR = High performance 6.2 litre, dry sump, no clutch (K), no external compressor (R), camshaft-driven magneto (no M) (some Panzer II)
• HL108 TUKRM = High performance 10.8 litre, wet sump, clutch, belt-driven compressor, schnapper magneto (Sd.Kfz. 9)
• HL120 TRM = High performance 12.0 litre, dry sump, no clutch (K), schnapper magneto (Panzer III)

{{Gallery

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| File:Maybach HL 42 TRKM.jpg

| alt1=

| Maybach HL42 TRKM (intake side) with most ancillaries removed. Oil reservoir (TR dry sump) at lower centre; intake manifold and twin vertical holes for carburetter (centre); some of the clutch mechanism (K) partly obscured (far left); the magneto (M), driven off the flywheel, fits in the large hole to the left of the oil reservoir;{{efn|The serial number stamped on the magneto housing appears to be MOT 551253}} the fuel pump attaches to the two threaded studs directly below.

| File:Maybach HL120.jpg

| alt2=

| Maybach HL120 (flywheel end). Center top: black air cleaner, above twin Solex carburettors. Top right: the top of the driving pulley for the compressor (partially obscured). Centre: camshaft cover with retaining knobs, above darker gray exhaust manifold. Lower right: Oil cooler. Left lower centre: magneto.

| File:Munster Maybach HL120 (dark1).jpg

| alt3=

| Maybach HL120 TRM with cam cover cut away, showing helical-cut camshaft driving pinion, and twin shafts carrying the rocker arms activated by the central camshaft (hidden). Also, at centre far-right: cylindrical oil cooler (water jacket cut away) with coiled copper oil pipe, and cut-off coolant hose below it.

| File:Maybach HL 210 P45 front-top2 2017 Bovington.jpg

| alt4=

| Maybach HL210 P45, originally fitted in Tiger 131. Note the right-angle shape of the cam followers, with rollers bearing on the camshaft lobes (partially visible just above the two leftmost inlet valve springs). The thin slotted brass guides are for setting the tappet clearances.{{efn|Note the guide positioning and excessive tappet clearance of the far right inlet valve.}} The camshaft drive pinion has straight-cut teeth, which are noisier at high revs, but cheaper to manufacture.

| File:Maybach HL 210 P45 front-bottom 2017 Bovington.jpg

| alt 5=

| Maybach HL210 P45. The entire engine block is a single aluminium alloy casting from the top of the cylinders to the bottom of the crankcase. Photo shows underside of crankcase, with part of tunnel crankshaft. The crank webs are circular, supported by outsize bearings which locate into machined housings. Note centre bearing with groove (partially shown) for semi-circular retaining rings.A clearer photo is here: {{cite web |title=Tiger 131 restoration: the final stages? |website=The Tiger Collection |date=20 February 2019 |url=https://blog.tiger-tank.com/tanks/part-viii-the-final-stages/ |access-date=25 June 2021}} The flat bottom cover (removed) would be bolted to the underside of the crankcase.

| File: Maybach HL 230 Technikmuseum Sinsheim.jpg

|alt6=

| Maybach HL230, oil cooler side.{{efn|HL230. From top right: magneto housing, between hot coolant pipes (to radiator). Immediately below magnetos: fan drive housing (yellow interior) with locating hole for fan drive shaft (four bolts). Centre right: cast iron exhausts. Lower right: harmonic damper with splined centre. Far lower right, beneath yellow lifting eye: oil reservoir (partially hidden), with hole for inertia starter handle (hand crank).[https://www.youtube.com/watch?v=2ijq5m6UIVw Hand-cranking various tanks] {{Webarchive|url=https://web.archive.org/web/20200228173837/https://www.youtube.com/watch?v=2ijq5m6UIVw |date=2020-02-28 }} (Youtube) Centre, below exhaust: dynamo (black). Lower centre: oil cooler, with cold water inlet (from radiator). Far lower left: oil filter (at 45°). Top centre: carburettor cover, with holes for twin air filters}}

}}

Between 1934 and 1950, Maybach designed approximately 100 different types of HL engines, of which about 70 reached at least bench testing. Some were 'proof of concept' single-cylinder designs.{{harvnb|Zima|1987|p=needed}}, as reviewed by {{cite web |last=NF |title=Разработка танковых двигателей фирмы Maybach в 1930-1940-е годы |trans-title= Development of Maybach tank engines in the 1930s-1940s |date=4 March 2019 |website=Альтернативная история (Alternative history) |language=Russian |access-date=26 July 2021 |url=http://alternathistory.com/razrabotka-tankovih-dvigatelei-firmy-maybach-v-1930-1940-e-gody/#novyj-modelnyj-ryad-dvigatelej-s-karterami-otlitymi-iz-alyuminievyh-sp}} Many of these engines were the direct result of orders for an engine of a specific power and physical size, originating from {{lang|de|Waffenamt Prüfwesen 6}} ('Weapons Testing [division] 6', {{lang|de|Wa. Prüf. 6|italic=yes}}, responsible for tanks, armoured vehicles and motorized equipment) of the Heereswaffenamt.

Fewer than twenty of these basic designs were actually manufactured as quantity series production engines, and are shown in the first table. Many these engines were manufactured in their thousands by Maybach and its licensed manufacturers.

The second table lists Maybach engines which, although fully functioning, were only made in small quantities and often assigned to projects in the VK series ({{lang|de|Versuchskampffahrzeug|italic=yes}}, "research/experimental fighting vehicle"). Others in the second list were intended for tanks and other AFVs which never even left the drawing board, the so-called 'Paper Panzers' such as the Entwicklung series, from de:{{lang|de|Entwicklung|italic=yes}}, "development").See, for example, {{harvnb|Jentz|Doyle|2001}} and {{harvnb|Jentz|Doyle|2002c}}.

{{See also|Maybach HL230}}

File:Bundesarchiv Bild 101I-022-2936-27, Russland, Panzer VI (Tiger I), Wartung.jpg ]]

A proposed replacement for the Panzer IV had been considered since around 1937. What became the Tiger tank went through a series of specifications, with the final revision (VK 4501) being made in May 1941.{{sfn|Perrett|1981|pp=3-4}} Only a month later, the German armies invading Russia encountered the superior T-34 and KV-1: by December 1941 a specification for a 30-ton medium tank (which became the Panther) had been proposed as an immediate response to the Soviet tank threat.{{sfn|Doyle|Jentz|1997|p=4}}{{efn|Although the T-34 and KV tanks were almost impervious to the German 37mm anti-tank guns and the guns of the Panzer III and IVs,{{sfn|Zaloga|1994|pp=14-15}} they were not the primary reason why the German offensive ground to a halt by the end of 1941. Both sides suffered huge losses of personnel and matériel. The Battle of Smolensk delayed the German push towards Moscow.{{sfn|Bellamy|2007|p=240}} Despite staggering losses including the Battle of Bryansk, the Red Army (backed up by physical defences constructed by innumerable civilian forces, both women and men, and the implacable weather - the rasputitsa) kept the invading forces at bay for long enough to keep re-located tank production going over the winter.{{sfn|Zaloga|1994|pp=14-17, 18-21}} }}

Development of the two tanks continued simultaneously: the Tiger prototype was demonstrated to Hitler on his birthday in April 1942,{{sfn|Perrett|1981|p=4}} and the first of two Panther prototypes was ready in August 1942.{{sfn|Doyle|Jentz|1997|p=4}}

The weight of the Tiger had increased considerably since its inception, and although it was now considerably heavier than the Panther medium tank, Maybach proposed fitting almost exactly the same 21-litre V-12 650 hp engine in both tanks. To save weight, the cylinder block was cast in aluminium alloy, with cast iron liners. The pistons were made of low-expansion aluminium-silicon alloy with Si content of nearly 20%.{{sfn|Saeed|Khan|Hadfield|Davies|2013|p=640}} The engine for the original 30-ton Panther project was the Maybach HL210 P30, while the 45-ton specification for the Tiger received the HL210 P45. The main visible difference was the arrangement of the coolant ducts exiting the cylinder heads, since the Panther and Tiger had different flows through their radiators.{{efn|The HL210 P30 is externally almost identical to the HL210 P45, apart from the hot coolant ducts (to radiator) at the flywheel end. On the P30 they are visually similar mirror images, and each duct is separately piped to the radiators on either side. On the P45 they are of unequal appearance, and are linked over the top of the fan drive housing into a 'Y'-fitting: a single pipe feeds the top of the offside radiator, which is coupled at the bottom to the top of the nearside radiator. The lower outlet of this feeds the oil cooler and then the water pump at the flywheel end. Photos make this much clearer.}}

Quantity series production of the PzKpfw VI Tiger (Ausf. H) with the HL210 P45 engine began in August 1942,{{sfn|Perrett|1981|p=4}} and it is possible that production of the Panther's HL210 P30 was begun at much the same time. The first battalions to be equipped with the Tigers were the 502nd Heavy Panzer Battalion on the Eastern Front near Leningrad, and the 501st Heavy Panzer Battalion which was sent to Tunisia. Unfortunately, it swiftly became apparent that the Tiger was seriously underpowered, and the rush into production of the new engines meant that the inevitable design defects had not been ironed out. Nevertheless, when the new Tigers arrived in Russia, there was only one spare engine and one transmission for every 10 tanks. A critical lack of spare parts meant that most of them were out of commission within a short period.{{sfn|Müller-Hillebrand|1982|pp=24-25}}

File:Bovington 178 Jagdtiger engine 1.jpg

The first PzKpfw V Panthers (Ausf. D) were similarly ill-fated; series production began in January 1943, but when they arrived in Russia in the spring the faults (including the steering and leaking engine gaskets) were so egregious that the entire batch had to be returned to Germany.{{sfn|Müller-Hillebrand|1982|p=25}} A special plant for rebuilding the Panthers was established near Berlin.{{sfn|Müller-Hillebrand|1982|p=25}} A report by Oberstleutnant Reinhold, attached to the 4th Panzer Army during Operation Citadel in July 1943, stated: "Mechanical Deficiencies: The cause for motor failures is still not known. It is possibly traceable to the short run-in time and unskilled drivers. Motors were over-revved. This caused overheating and broken connecting rods. In many cases fuel pumps failed. The pump seals leaked and pump membranes were defective. Leaks in oil line and fuel line connections increased the danger of fire."{{sfn|Jentz|1996|pp=100-101}}

Another report from Oberstleutnant Mildebrath for Heinz Guderian, the Generalinspekteur der Panzertruppen in September 1943, about the 96 Panthers of the 2nd Battalion (Abteilung) of the 23rd Panzer Regiment, part of the 23rd Panzer Division:

:As before, the troops are still excited about the tactical capabilities of the Panther, but deeply disappointed that the majority of the Panthers can't engage in combat due to a miserable motor and other mechanical weaknesses. They would gladly give up some speed, if automotive reliability could be gained. Until the same automotive reliability as the Panzer III and IV is achieved, the Abteilung must be provided with extra repair parts, especially motors and final drives, and the necessary equipment and personnel to perform maintenance and repairs.{{sfn|Jentz|1996|p=115}}

At Kursk, 5–13 July 1943, 25 engines failed within 9 days (these would probably have been HL210 P30s) faults included piston rod bearing damage, broken con rods, damaged pistons, tears (cracks) in the cylinder sleeves, burnt cylinder head gaskets, and water in the exhaust. Also high oil consumption, and spark plugs oiling up. Fuel lines weren't sealed properly, leading to fires in the engine compartment. Final drives were too weak and had a high failure rate. The main clutch was fine except when used for towing, and the gearbox also functioned without problems - it always seems to have worked well, with very few problems ever reported. The running gear also functioned well.{{sfn|Spielberger|1993b|p=96}}

In the meantime, Maybach re-designed the HL210, replacing the alloy cylinder block with a traditional cast-iron one. Although there was no space for a physically larger engine, the cylinders were capable of being bored out without compromising the engine's integrity. The cast-iron HL230 engines weighed around {{convert|1,400|kg}}, considerably more than the {{convert|1,050|kg}} of the HL210.{{sfn|HL210/230 Workshop Manual|1944|p=8}} The new HL230 23-litre engines were installed from May 1943 in the latest production Panthers as the P30, and in Tigers as the P45.{{cite web |last=Eberl |first=E. |title=The production periods of the Panther versions and the technical changes over the production periods |website=Panther 1944 |url=http://www.panther1944.de/index.php/en/sdkfz-171-pzkpfwg-panther/technik/technical-changes |access-date=16 May 2020}} NB Engine changes half-way down in light grey.{{sfn|Jentz|Doyle|2000b|pp=75-6}}{{sfn|Jentz|Doyle|2002|p=14}}{{efn|The different cooling duct arrangements were carried over to their respective vehicles, and both designs received central twin magnetos, a new placement of the oil filter, and twin air filters in place of the triple cyclone housings.}} Although they produced 700PS @3,000 rpm, from November 1943 they were governed at the factory to 2,500 rpm to increase engine life, which limited them to the same 650 PS as the HL210.{{sfn|Jentz|Doyle|2000b|p=76}}

Despite all the changes, the up-engined Panther Ausf. A with the HL230 P30 (which didn't arrive in Russia until late 1943) suffered from over-heating, fires in the engine compartment and blown head gaskets.{{sfn|Jentz|1995|pp=61–62}} The head gasket problem was solved in August 1943 by pressing copper rings into grooves to seal the head. A new design of piston was fitted to the HL230 P45 which reduced the compression ratio slightly.{{sfn|Jentz|Doyle|2000b|pp=75-6}} In November 1943 a governor was installed in the HL230 P45 which limited the maximum revs to 2,500 rpm, and the maximum speed under full load to {{convert|38|km/h|abbr=on}}. Some new and rebuilt motors from October had faulty bearings installed causing frequent failures: improved bearings were installed in new HL230 P45s from January 1944.{{sfn|Jentz|Doyle|2000b|p=76}}

As a result of these improvements the Panther became much more reliable. In Nachtrichtenblatt der Panzertruppen ('Newssheet of the Panzer Troops') for March 1944,{{efn|NB Here Jentz confuses this newsletter for the troops with Guderian's detailed monthly reports on tank status to Hitler, Notizen des Generalinspekteurs der Panzertruppen. Most of the issues of the Nachtrichtenblatt are available online, sadly excluding No. 9 of March 1944.{{cite web |title=Nachrichtenblatt der Panzertruppen |website=Sturmpanzer.com |access-date=5 August 2023 |url=https://www.sturmpanzer.com/Default.aspx?tabindex=5&tabid=620&item=3&sec=0}} }} Guderian could include the combat report of an unnamed Panther battalion (possibly 1/1st Panzer Regiment) which had travelled an average of 700 kilometers per tank, with only 11 engines needing replacement.{{sfn|Jentz|1996|pp=129-131}} And in a situation report to Hitler on late June 1944 on the Battle for Normandy, he comments on the Panther's propensity to catch fire, and the mismatch between the durability of the engine and the transmission: "However, the Panther burns astonishingly quickly. The lifespan of the Panther's engine (1400 to 1500 kilometers) is considerably higher than that of the Panther's final drives. A solution is urgently needed!"{{sfn|Jentz|1996|p=184}}{{cite report |last=Guderian |first=Heinz |author-link=Heinz Guderian |title=Notiz uber Führervervortrag am 28.6, 24 Uhr 00 |page=8 |date=30 June 1944 |language=de |publisher=Generalinspekteur der Panzertruppen |series=Nr. 053/44 |url=https://wwii.germandocsinrussia.org/de/nodes/1280-akte-477-okh-generalinspekteur-der-panzertruppen-notizen-des-generalinspekteurs-der-panzertru#page/9/mode/inspect/zoom/4 |via=Deutsch-Russisches Projekt zur Digitalisierung deutscher Dokumente in Archiven der Russischen Föderation }} NB This site contains many of these Notizen . Such a solution was never found. A French post-war report The Panther 1947 stated that although the engine could last for up to 1500 km, average 1000 km, the final drives only had a fatigue life of 150 km. The engine could be replaced in 8 hours by a trained mechanic Unteroffizier and 8 men with a tripod beam crane or Bergepanther.{{sfn|Spielberger|1993b|pp=160–161}}

Maybach didn't separate the production statistics of the 210 from the 230. Altogether, production of both types amounted to 153 in 1942, 4,346 in 1943, and 1,785 HL230s up to April 1944. In late April 1944 an Allied bombing raid put the Maybach factory out of action for six months.{{sfn|Jentz|Doyle|2000b|p=70}} Production was transferred to the Auto Union factory in Chemnitz, which delivered 219 HL230 engines to Henschel in 1944. A total of 4,366 HL230s from April for Panthers and Tigers were delivered from April 1944 to 1945.{{sfn|Jentz|Doyle|2000b|p=70}}

;Identifying HL210 and HL230 types:

• HL210: three air filters; magnetos are located separately at the end of each camshaft; on the oil cooler side the oil filter sits at a relatively upright angle, approx. 70°.
• HL230: two air filters: magnetos are located centrally in a twin housing between the cylinder heads; oil filter sits at approx. 45°.
• P30: the twin cast iron hot coolant ducts are symmetrical and visually similar, with separate feeds to l.h and r.h. radiators..
• P45: the coolant ducts are siamesed into a single pipe leading to the r.h. radiator.

Despite their similar appearances, the P30 and P45 versions had numerous small differences. The 230 P30 could be swapped with the P45 from a Tiger, but 105 separate parts needed to be removed from the P45 and replaced by 107 parts from the P30.{{sfn|Trojca|Molski|2006|p=35}}

According to the head of Henschel's design office in 1945, the assembly shop felt that the engine layout of the P30 version of the HL230 had much better attributes and was better developed for assembly work than the HL230 P45 fitted to the Tiger Ausf. E.{{sfn|Jentz|Doyle|1997b|p=64}}

Maybach continued to develop increasingly powerful 4-stroke water-cooled gasoline-powered engines during the war. One such {{lang|de|Versuchsmotor|italics=yes}} which never reached series production was the HL234, a development of the HL230.{{efn|Most of the information about this engine comes from the Report on the Interrogation of Dipl.-Ing. Ernest Kniepkamp (a.F.Vs.) by W. J. Semmons for British Intelligence Objectives Sub-committee (BIOS) c.1946 (Final Report No. 34). Typescript reproduced in Appendix III of {{harvnb|Estes|2018|pp=157–163}} § }}

The intention was to develop a fuel-injected and supercharged engine, but only the fuel injection mechanism (by Bosch) was working by the end of the war.{{sfn|Jentz|Doyle|2001|p=20-18}} The engine displaced approximately 23.4 litres, and the un-supercharged version was capable of developing 850 PS @2,800 rpm, with maximum torque of {{convert|260|kgm|Nm lbft}} @1,750 rpm{{refn|From graph in {{harvnb|Spielberger|1993b|p=175}} At the time Germany used the Kilopondmetre abbreviated as mkp or mkg. 1 mkp {{=}} 9.80665 N·m {{=}} 7.233 lb·ft.}}, and 900 PS @3,000 rpm{{sfn|Jentz|Doyle|2001|p=20-18}} Only a few pilot fuel-injection engines were built.{{sfn|Estes|2018|loc=Appendix II, p. 7}} The fuel-injected and supercharged version (one engine completed) would hopefully deliver around 1200 PS.{{sfn|Estes|2018|loc=Appendix II, p. 7, III p. 2}}

The main supercharger was to have been driven by its own twin-cylinder supercharged 1 litre engine of 70 PS mounted in the V of the HL234 (where the carburetors were located in a normally-aspirated engine), but this part of the design was never completed.{{efn|This auxiliary engine may have been the HL10, bore * stroke 100mm x 70mm, 1.0996 litres, 70 PS @5000 rpm.{{sfn|Spielberger|1998|p=209}} }} By April 1943 the crankshaft bearings and connecting rods from the HL230 had also been strengthened, and the direct fuel injection system was working - but the supercharger was not yet fully developed.{{sfn|Jentz|Doyle|2001|p=20-18}} Other improvements over the HL230 included water-cooled spark plugs; an improved intake manifold for better airflow; and improved exhaust manifold as well.{{sfn|Estes|2018|loc=Appendix III p. 4}} Instead of coil-type valve springs the HL 234 used much stronger Belleville washers, which reduced valve opening times.{{sfn|Estes|2018|loc=Appendix III p. 3}} Problems with rubber seals and copper [head] gaskets were solved by adopting designs used in the Rolls-Royce Merlin engine.{{sfn|Estes|2018|loc=Appendix III p. 4}}

The first HL234 {{lang|de|Versuchsmotor|italics=yes}} was planned to be delivered in early 1945 to the Kummersdorf proving ground and was proposed in January 1945 as an upgraded power plant for the Tiger II, but had not yet been tested in a tank by that date.{{sfn|Jentz|Doyle|1997b|pp=145-6}} It was also proposed for the Panther II at a later prototype stage, but the project was discontinued.{{sfn|Doyle|Jentz|1997|p=10}} Similarly, the E.50/E.75 tank series for which the engine was also intended were never built before the war's end, with only development of individual components taking place.{{sfn|Jentz|Doyle|2001|p=20-18}}

Maybach also developed a smaller 12-litre version on similar lines to the HL234. It weighed 600 kg, developing 500 PS without supercharger and 700 PS at 3,800 rpm supercharged,{{sfn|Estes|2018|loc=Appendix III p. 4}} but like so many other German war-time projects, it never came to fruition.

An exception to Maybach's detailed naming system described above is the Maybach DSO8 V-12 engine fitted to early Sd.Kfz. 8s. It was derived from the DS7 ({{langx|de|Doppel Sechs 7|italics=yes}}) (i.e. Double-Six, 7 litres) fitted in the Maybach Zeppelin luxury car from 1929, a 7.0 litre (6,971 cc) V12 engine that produced 150 horsepower at 2,800 rpm,{{sfn|Ludvigsen|2005|pp=159–160}} and from the later DS8 8-litre (bore x stroke=92*100 mm,{{cite web |title=Technical Data Light-alloy V12 engine |website=Mercedes-Benz Group Media |url=https://group-media.mercedes-benz.com/marsMediaSite/en/instance/ko/Technical-Data-Light-alloy-V12-engine.xhtml?oid=9274259 |date=16 January 2002 |access-date=21 March 2022}} 7977 cc, 486 cubic inches) which developed 200 bhp (149 kW; 203 PS) at 3200 rpm.{{sfn|Ludvigsen|2005|p=160}} The engine block and pistons were made of light aluminium alloy with cast iron liners. A 1938 Maybach Zeppelin DS8 also fitted with a Maybach Variorex vacuum shift eight-speed gearbox (both the first 8-speed and first 8-speed manual gearbox), sold at auction in 2012 for 1.3 million Euros.{{cite web |title=Bidding frenzy erupts as Maybach decimates estimate |date=13 August 2012 |url=https://www.classicandsportscar.com/news/classic-car-auctions/bidding-frenzy-erupts-as-maybach-decimates-estimate |access-date=21 March 2022}}

John Milsom mentions two versions of the DSO8, one with a power output of 150 bhp fitted to the prototype DB ZD5 as early as 1931, and one of 200 bhp found in the early production Sd.Kfz. 8 (DB s 7) from 1934 to 1936.{{sfn|Milsom|1975|p=13}} A DSO8 developing 155 PS @2600 rpm was also recommended for export models of the Panzer III MKA ("mittlerer Kampfwagen fur Ausland") in August 1937, since the proposed 200 PS Maybach HL76 was "slow to come into production",{{sfn|Jentz|Doyle|2006|p=3-70}} and may never have reached series production at all.

The DSO8 also powered three Swedish Stridsvagn m/31 prototypes in the early 1930s. A 150 hp DSO8 is also found in the Strv FM/31 Landsverk L-30 dating from 1931, examples of both are preserved in the Arsenalen Försvarsfordonsmuseum in Strängnäs, central Sweden.{{cite web |url=http://www.tugboatlars.se/Arsenalen.htm |website=Arsenalen Försvarsfordonsmuseum |title=Arsenalen Försvarsfordonsmuseum |language=Swedish |access-date=28 January 2021 |archive-date=24 July 2020 |archive-url=https://web.archive.org/web/20200724090658/http://www.tugboatlars.se/Arsenalen.htm |url-status=live }}Photo on Wikimedia Commons: Stridsvagn FM/31{{efn|A number of photos and drawings can be found here: {{cite web |url=http://ftr.wot-news.com/2014/03/12/swedish-tanks-part-ii-strv-m31-strv-fm31/ |title=Swedish Tanks – Part II: Strv m/31 & Strv fm/31 |website=For The Record |access-date=28 January 2021 |author1=((sp15)) |date=12 March 2014}} }}

German WWII half-track prime mover numbering may appear not to be strictly logical: the two smallest vehicles were introduced after most of the larger artillery tractors were in production.{{sfn|Milsom|1975|pp=7-8}}{{efn|They were introduced in the following order: Sd.Kfz. 7 (KM m8 in 1934), Sd.Kfz. 6, 8, 11, 10, 9. {{harv|Milsom|1975|pp=7–8}} }} In ascending order of engine size and therefore towing capacity, they were designed to tow the following:{{sfn|Milsom|1975|pp=6-7}}

• Sd.Kfz. 10 (1-ton), 3.7 cm PaK 36 & 5cm PaK 38, and SP 2cm Flak 30
• Sd.Kfz. 11 (3-ton), 7.5 cm Pak 40 & 41, 10.5 cm leFH 18 and 15 cm sIG 33, 7.5 cm Flak. L/60, standard and Nebelwerfer ammunition trailers
• Sd.Kfz. 6 (5-ton), 10.5 cm leFH 18, 7.5 cm Flak. L/60. Mainly used as engineer/Pioneer equipment and personnel carrier{{sfn|Milsom|1975|p=11}}
• Sd.Kfz. 7 (8-ton), 8.8 cm Flak, 10 cm K.18, 15 cm sFH 18, 15 cm Kanone 18 (2 separate loads); SP for 3.7 cm Flak & 2cm Flakvierling
• Sd.Kfz. 8 (12-ton), 10.5 cm FlaK 38, 17 cm Kanone 18 and 21 cm Mörser 18 (2 separate loads)
• Sd.Kfz. 9 (18-ton), 24 cm Kanone 3 (5 separate loads), 35.5 cm Mörser (7 separate loads), 6 or 10-ton crane, or tank recovery

As Maybach designed new, more powerful engines, all these vehicle types received at least two and up to four different engine models during production of the latest batches. There remained the necessity of attempting to produce either spare parts or complete new engines, just to keep the older vehicles running.

• Maybach HL230
• GT 101, BMW-based turboshaft engine project for German AFVs
• Maybach I and II, high command bunkers near Berlin

;Notes

{{notelist|30em}}

;Citations

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{{columns-list|colwidth=20em|

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|first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Panzerkampfwagen III Ausf. A, B, C & D

|series= Panzer Tracts 3-1

|date=2006

|place=Boyds, MD

|publisher=Panzer Tracts

|isbn=978-0-9771643-4-9}}

• {{cite book

|last1=Jentz

|first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Panzerkampfwagen III Ausf. E, F, G & H

|series=Panzer Tracts 3-2

|date=2007a

|isbn=978-0-9771643-9-4

|place=Boyds, MD

|publisher=Panzer Tracts}}

• {{cite book

|last1=Jentz |first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Panzerkampfwagen II Ausführung G, H, J, L, and M development and production from 1938 to 1943

|series=Panzer Tracts No. 2-2

|date=2007b

|isbn=0-9771643-8-1

|place=Boyds, MD

|publisher=Panzer Tracts}}

• {{cite book

|last1=Jentz |first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Panzerkampfwagen II Ausführung a/1, a/2, a/3, b, c, A, B, and C development and production from 1934 to 1940

|series=Panzer Tracts No. 2-1

|date=2008a

|isbn=978-0-9815382-2-8

|place=Boyds, MD

|publisher=Panzer Tracts}}

• {{cite book

|ref=

|last1=Jentz

|first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Leichter Schutzenpanzerwagen: (Sd.Kfz. 250) Ausf. A and B: History of Production, Variants, Organization and Employment from 1941 to 1945

|series=Panzer Tracts No. 15-1

|place=Boyds, MD

|publisher=Panzer Tracts

|date=2008b

|isbn=978-0-9815382-0-4}}

• {{cite book

|last=Jentz

|first=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Leichter Zugkraftwagen 1t: (Sd.Kfz. 10) Ausf. A und B and Variants: development and production from 1935 to 1945

|series=Panzer Tracts No. 22-1

|place=Boyds, MD

|publisher=Panzer Tracts

|date=2009

|isbn=0-9815382-5-8}}

• {{cite book

|last=Jentz

|first=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Leichter Zugkraftwagen 3 t: (Sd.Kfz. 11) and Variants: development and production from 1934 to 1945

|series=Panzer Tracts No. 22-2

|place=Boyds, MD

|publisher=Panzer Tracts

|date=2009b

|isbn=0-9815382-6-6}}

• {{cite book

|last1=Jentz

|first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Flakpanzerkampfwagen IV and other Flakpanzer projects: development and production from 1942 to 1945

|series=Panzer Tracts 12-1

|date=2010a

|place=Boyds, MD

|publisher=Panzer Tracts

|isbn=978-0-9815382-7-3}}

• {{cite book

|last=Jentz

|first=Thomas L.

|last2=Doyle

|first2=H. L.

|title=mittlerer Zugkraftwagen 5t (Sd.Kfz. 6) and schwerer Wehrmachtsschlepper: development and production from 1934 to 1945

|series=Panzer Tracts No. 22-3

|place=Boyds, MD

|publisher=Panzer Tracts

|date=2010b

|asin=B0045WAGIK}}

• {{cite book

|last1=Jentz |first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Panzerkampfwagen II Ausführung D, E, and F development and production from 1937 to 1942

|series=Panzer Tracts No. 2-3

|date=2010c

|asin=B0045W90UK

|place=Boyds, MD

|publisher=Panzer Tracts}}

• {{cite book

|last1=Jentz

|first1=Thomas L.

|last2=Doyle

|first2=H. L.

|title=Panzer Production from 1933 to 1945

|series=Panzer Tracts 23

|date=2011

|place=Boyds, MD

|publisher=Panzer Tracts}}

• {{cite book

|last=Jentz

|first=Thomas L.

|last2=Doyle

|first2=H. L.

|last3=Friedli

|first3=Lukas

|title=Mittlerer Zugkraftwagen 8t (Sd.Kfz. 7)

|series=Panzer Tracts No. 22-4

|place=Boyds, MD

|publisher=Panzer Tracts

|date=2013}}

• {{cite book

|ref=

|last=Koch

|first=Fred

|title=Motoren Und Getriebe Deutscher Panzer 1935–1945

|series=Waffen Arsenal 182

|date=2000

|language=German

|place=Wölfersheim-Berstadt

|publisher=Podzun-Pallas-Verlag

|url=https://archive.org/details/WaffenArsenal182MotorenUndGetriebeDeutscherPanzer19351945/mode/2up

|isbn=3-7909-0695-6}}

• {{cite thesis

|ref=

|last=Kuhn

|first=Michael

|type=D. Phil. dissertation

|title=Die Tübinger katholischen Theologiestudenten im nationalsozialistischen Arbeitsdienst 1933–1945: Anhang 1: Quellen und Materialien

|date=2017

|publisher=Institut für Gesellschaftswissenschaften der Pädagogischen Hochschule Schwäbisch Gmünd

|language=German

|url=https://phsg.bsz-bw.de/frontdoor/deliver/index/docId/63/file/Michael_Kuhn-Die_T%c3%bcbinger_katholischen_Theologiestudenten_Anhang1.pdf

|access-date=16 May 2020}}

• {{cite book

|last=Ludvigsen

|first=Karl

|title=The V12 Engine

|chapter=Chapter 7: Teutonic Twelves

|author-link=Karl Ludvigsen

|publisher=Haynes Publishing

|location=Sparkford, Yeovil

|date=2005

|isbn=1-84425-004-0}}

• {{cite book

|ref={{harvid|Mercillon|n.d.|pp=26-7}}

|last=Mercillon

|first=Patrick H.

|chapter=AMX 50

|pages=26–27

|title=Les Chars Français du Musée des Blindés

|place=Saumur, France

|publisher=Centre de Documentation sur les Engins Blindés

|language=fr}}

• {{cite book

|ref=

|last=Milsom

|first=John

|title=German Half-tracked Vehicles of World War 2

|place=London

|publisher=Arms and Armour Press

|date=1975

|url=https://www.scribd.com/doc/122233277/Arms-and-Armour-Press-German-Half-Tracked-Vehicles-of-World-War-2

|isbn=0-88254-354-7}}

• {{cite book

|ref=

|last=Munch

|first=Karlheinz

|title=The Combat History of German Heavy Anti-Tank Unit 653 in World War II

|edition=illustrated, reprint

|publisher=Stackpole Books

|date=2005

|isbn=978-0-8117-3242-0

|url=https://books.google.com/books?id=eONpj6gjD1UC}}

• {{cite book

|ref=

|last=Müller-Hillebrand

|first=Burkhart H.

|title=German Tank Maintenance in World War II

|publisher=Department of the Army

|series=DA Pamphlets, No. 20-202

|orig-date=1954

|date=1982

|edition=Facsimile

|url=https://history.army.mil/html/books/104/104-7/cmhPub_104-7.pdf}}

• {{cite book

|ref={{harvid|HL210/230 Workshop Manual|1944}}

|last=Oberkommando des Heeres

|title=Panzerkampfwagen Panther. Werkstatthandbuch zum Maybach-Motor HL230 P30 – HL210 P30

|trans-title=Workshop Handbook

|date=1 April 1944

|series=Publication D 655/31c

|publisher=Heereswaffenamt: Amtsgruppe für Entwicklung und Prüfung. I.A.[Im Auftrage=p.p.] Holzhäuer

|language=German

|url=https://pdfcoffee.com/qdownload/panzerkampfwagen-panther-werkstatthandbuch-vom-151944-pdf-free.html}}

• {{cite book

|ref=

|last=Perrett

|first=Bryan

|others=Illustrated by David E. Smith and Mike Chapell

|date=1980

|title=Panzerkampfwagen III

|place=London

|publisher=Osprey Publishing|isbn=0-85045-362-3}}

• {{cite book

|ref=

|last=Perrett

|first=Bryan

|others=Illustrated by David E. Smith

|title=The Tiger Tanks

|place=London

|publisher=Osprey Publishing

|date=1981

|isbn=0-85045-389-5}}

• {{cite book

|ref=

|last=Perrett

|first=Bryan

|title=German Light Panzers 1932–42

|others=Illustrated by Peter Sarson & Terry Hadler

|place=Oxford

|publisher=Osprey Publishing

|date=1998

|edition=revised

|isbn=1-85532-844-5}}

• {{cite book

|ref=

|last=Perrett

|first=Bryan

|others=Illustrated by David. E. Smith & Jim Laurier

|date=1999

|title=Panzerkampfwagen IV medium tank: 1936–1945

|edition=revised

|place=Oxford

|publisher=Osprey Publishing

|isbn=978-1-85532-843-3}}

• {{cite journal

|ref=

|last1=Saeed

|first1=Adil

|last2=Khan

|first2=Zulfiqar A.

|last3=Hadfield

|first3=Mark

|last4=Davies

|first4=Steve

|title=Material Characterisation and Real Time Wear Evaluation of Pistons and Cylinder-liners of the Tiger 131 Military Tank

|journal=Tribology Transactions

|volume=56

|issue=4

|date=July 2013

|pages=637–644

|doi=10.1080/10402004.2013.771416

|s2cid=53341629

|url=http://eprints.bournemouth.ac.uk/20619/5/ZK_Tribology_Transaction_Feb_2013.pdf

|access-date=19 June 2020}}

• {{cite book

|last1=Sawicki

|first1=Robert

|last2=Ledwoch

|first2=Janus

|title=Mittlere ZgKw 5t: Sd Kfz 6

|place=Warsaw

|publisher=Wydavnictwo "Militaria"

|language=Czech, English

|date=2007

|isbn=978-83-7219-287-5}}

• {{cite journal

|last=Schaffers

|first=Joseph

|title=Electro Steel—A New Metallurgical Product

|journal=The Horseless Age

|volume=XXVI

|issue=24

|date=14 December 1910

|place=New York

|url=http://photos.justoldtrucks.com/gs/handler/getmedia.ashx?moid=30421&dt=2&g=2}}

• {{cite book

|last=Speer

|first=Albert

|title=Inside the Third Reich

|publisher=The Macmillan Company

|date=1970

|url=https://archive.org/details/Inside_the_Third_Reich_Albert_Speer/page/n271/mode/2up}}

• {{cite book

|last=Spielberger

|first=Walter J.

|title=Die Panzerkampfwagen I und II und ihre Abarten

|others=Illustrated by Hilary L. Doyle and Uwe Feist

|publisher=Motorbuch Verlag Stuttgart

|language=German

|date=1974

|isbn=3-87943-335-6}}

• {{cite book

|last=Spielberger

|first=Walter

|title=Die Rad- und Vollketten Zugmaschinen des Deutschen Heeres 1870–1945

|place=Stuttgart

|publisher=Motorbuch Verlag

|others=Scale drawings by Hilary L. Doyle

|date=1978

|url=https://archive.org/details/CAMIONESSEMIORUGALEMANES/page/n194/mode/1up

|isbn=978-3-87943-528-9}}

• {{cite book

|last=Spielberger

|first=Walter

|title=Die Halbkettenfahrzeuge des Deutsches Heeres 1909–1945

|series=Militarfahrzeuge Band 6

|language=German

|others=(Scale drawings by H.L. Doyle, colour illustrations by Uwe Feist)

|place=Stuttgart

|publisher=Motorbuch Verlag

|edition=4th

|date=1993

|url= |isbn=3-87943-403-4}}

• {{Cite book

|last=Spielberger

|first=Walter

|title=Panther & its variants

|place=Atglen, PA

|publisher=Schiffer Military/Aviation History

|date=1993b|isbn=0-88740-397-2}}

• {{Cite book

|last=Spielberger

|first=Walter

|title=Panzer IV and its variants

|publisher=Schiffer Military History

|date=1993c

|location=Atglen, PA, USA|isbn=978-0-88740-515-0}}

• {{cite book

|ref=

|last=Spielberger

|first=Walter

|title=Sturmgeschütze: Entwicklung und Fertigung der sPak

|series=Militärfahrzeuge, Band 13

|language=German

|place=Stuttgart

|publisher=Motorbuch Verlag

|date=1994

|edition=2nd

|url=https://archive.org/details/WalterSpielbergerMilitaerfahrzeugeSturmgeschuetze/page/n34/mode/1up|isbn=3-613-01356-8}}

• {{cite book

|last=Spielberger

|first=Walter

|title=Der Panzerkampfwagen Tiger und seine Abarten

|edition=6th

|date=1998

|language=German

|place=Stuttgart

|publisher=Motorbuch-Verlag|isbn=3-87943-456-5}}

• {{cite book |last1=Trojca |first1=Waldemar |last2=Molski |first2=Woiciech |series=Tank Power |date=2006 |title=Panzerkampfwagen V Panther |volume=8 |publisher=AJ-Press |place=Gdańsk, Poland |isbn=83-7237-175-X |language=Polish, English}}
• {{cite book

|ref={{harvid|USSBS Report No. 85|1947}}

|title=Henschel and Sohn, Kassel, Germany

|publisher=United States Strategic Bombing Survey, Munitions Division

|date=January 1947

|edition=2nd

|series=Report No. 085 (Plant Report No. 7)

|url=https://books.google.com/books?id=XvAsAAAAIAAJ}}

• {{cite book

|ref={{harvid|U.S. Strategic Bombing Survey|1947}}

|title=Maybach Motor Works, Fredrichshafen, Germany

|publisher=U.S. Strategic Bombing Survey, Munitions Division

|series=Report No. 86

|date=January 1947

|edition=2nd

|url=https://books.google.com/books?id=evIsAAAAIAAJ&pg=PT1}}

• {{cite book

|last=Zaloga

|first=Steven J.

|others=Illustrated by Peter Sarson

|title=T-34/76 Medium Tank 1941–45

|date=1994

|series=New Vanguard 9

|place=Oxford

|publisher=Osprey Publishing|isbn=1-85532-382-6}}

• {{ cite book

|last=Zima

|first=Stefan

|title=Entwicklung schnelllaufender Hochleistungsmotoren in Friedrichshafen

|trans-title=Development of high-speed high-performance engines in Friedrichshafen

|series=Technikgeschichte in Einzeldarstellungen, Band 44/1987

|date=1987

|place=Düsseldorf

|publisher=VDI Verlag

|language=German|isbn=978-3-18-150044-6}}

}}

• [http://fahrzeuge-der-wehrmacht.de/Artikel/Motoren.html Photo gallery of various Maybach engine types] at Fahrzeuge der Wehrmacht (in German), including NL38 TR, HL42 TRKM, HL54 TUKRM, HL62 TUK, HL85 TUKRM, HL90, HL108 TUKRM, HL120, HL230 P30 & P45, and fuel-injection HL295 fitted in post-war AMX-50 prototype

Category:Engines