DR Class 99.77-79

{{no footnotes|date=December 2016}}

{{Infobox locomotive

| name = DR Class 99.77–79

| bgcolor = A00

| color = FFF

| image = Dampflok 99 789 der Fichtelbergbahn.jpg

| alt =

| caption = 99 789 on the Fichtelbergbahn in January 2013

| powertype = Steam

| designer =

| builder = VEB Lokomotivbau Karl Marx, Babelsberg

| ordernumber =

| serialnumber =

| buildmodel =

| builddate = 1952–1956

| totalproduction = 26

| rebuilder =

| rebuilddate =

| numberrebuilt =

| whytetype = {{whyte|2-10-2|T}}

| uicclass = 1′E1′ h2t

| DRGtype = K 57.9

| driver =

| gauge = {{track gauge|750mm}}

| leadingdiameter = {{convert|550|mm|ftin|frac=8|abbr=on}}

| driverdiameter = {{convert|800|mm|ftin|frac=8|abbr=on}}

| trailingdiameter = {{convert|550|mm|ftin|frac=8|abbr=on}}

| minimumcurve =

| wheelbase =

| wheelspacing = {{ubl|{{convert|1800|mm|ftin|frac=8|abbr=on}} +|{{convert|1000|mm|ftin|frac=8|abbr=on}} +|{{convert|1000|mm|ftin|frac=8|abbr=on}} +|{{convert|1000|mm|ftin|frac=8|abbr=on}} +|{{convert|1000|mm|ftin|frac=8|abbr=on}} +|{{convert|1800|mm|ftin|frac=8|abbr=on}} {{=}}}}

| engine total = {{convert|7600|mm|ftin|frac=8|abbr=on}}

| leading =

| drivers =

| coupled =

| trailing =

| length =

| over couplers = {{convert|11300|mm|ftin|frac=8|abbr=on}}

| over headstocks = {{convert|10000|mm|ftin|frac=8|abbr=on}}

| over buffers =

| width =

| height = {{convert|3550|mm|ftin|frac=16|abbr=on}}

| frametype =

| axleload = {{convert|8.6|t|abbr=on}}

| leadingbogie/pony=

| coupled all =

| coupled 1 =

| coupled 2 =

| coupled 3 =

| coupled 4 =

| coupled 5 =

| trail bogie/pony=

| weightondrivers = {{convert|42.8|t|abbr=on}}

| emptyweight = {{convert|41.5|t|abbr=on}}

| serviceweight = {{convert|55.0|t|abbr=on}}

| locoweight =

| fueltype = Coal

| fuelcap = {{convert|3.6|t|abbr=on}}

| watercap = {{convert|5.8|m3|impgal usgal|sigfig=3|abbr=on}}

| tendercap =

| sandcap =

| fireboxtype =

| firearea = {{convert|2.57|m2|abbr=on}}

| boiler =

| boilertype =

| pitch = {{convert|2100|mm|ftin|frac=8|abbr=on}}

| diameterinside =

| lengthinside = {{convert|3200|mm|ftin|frac=8|abbr=on}}

| smalltubediameter= {{convert|44.5|mm|in|frac=16|abbr=on}}, 92 off

| largetubediameter= {{convert|121|mm|in|frac=16|abbr=on}}, 28 off

| boilerpressure = {{convert|14|bar|kgf/cm2 psi|sigfig=3|abbr=on}}

| safetyvalvetype =

| feedwaterheater =

| fireboxarea = {{convert|8.5|m2|abbr=on}}

| tubearea = {{convert|36.6|m2|abbr=on}}

| archarea =

| fluearea = {{convert|31.8|m2|abbr=on}}

| tubesandflues =

| totalsurface = {{convert|76.9|m2|abbr=on}}

| superheatertype =

| superheaterarea = {{convert|28.8|m2|abbr=on}}

| cylindercount = Two, outside

| cylindersize = {{convert|450|x|400|mm|in|frac=16|abbr=on}}

| cylinderpressure =

| valvegear = Heusinger (Walschaerts)

| valvetype =

| valvetravel =

| valvelap =

| valvelead =

| transmission =

| trainheating =

| locobrakes =

| locobrakeforce =

| trainbrakes = Hardy vacuum brake,
Heberlein brake no longer provided

| safety =

| coupling =

| maxspeed = {{convert|30|km/h|mph|0|abbr=on}}

| indicatedpower = {{convert|600|PS|kW hp|sigfig=3|abbr=on}}

| poweroutput =

| tractiveeffort = {{convert|83.35|kN|kp lbf|abbr=on|-1}}

| factorofadhesion =

| operator = Deutsche Reichsbahn (GDR)

| operatorclass =

| powerclass =

| numinclass =

| fleetnumbers = 99 771 – 99 794
from 1970: 99 1771 – 99 1794

| officialname =

| nicknames =

| axleloadclass =

| locale =

| deliverydate =

| firstrundate =

| lastrundate =

| retiredate = from 1976

| withdrawndate =

| preservedunits =

| restoredate =

| scrapdate =

| currentowner =

| disposition =

| notes =

}}

The steam locomotives of DR Class 99.77–79 were ordered by the Deutsche Reichsbahn in East Germany after the Second World War. They were narrow gauge locomotives with a 750 mm rail gauge and were built for the narrow gauge lines in Saxony. The locomotives were largely identical to the DRG Class 99.73–76 standard locomotives (Einheitslokomotiven) built in the 1930s. To differentiate them from their predecessors they were described as Neubaulokomotiven or newly designed engines.