Southern Pacific class AC-5

{{one source|date=July 2016}}

{{Infobox locomotive

| name = Southern Pacific class AC-5

| image = USA 034 Berkeley 3.jpg

| caption = SP 4116 on freight passing Berkeley bound for Oakland, California

| powertype = Steam

| operator = Southern Pacific Railroad

| gauge = {{track gauge|ussg|allk=on}}

| operatorclass = AC-5

| driverdiameter = {{convert|63|in|m|3|abbr=on}}

| cylindersize = {{convert|24|×|32|in|0|abbr=on}} (bore × stroke)

| locoweight = {{convert|622600|lb|kg t|abbr=on}}

| weightondrivers = {{convert|482500|lb|kg t|abbr=on}}

| boilerpressure = {{convert|235|psi|MPa|abbr=on}}

| tractiveeffort = {{convert|116900|lbf|kN|abbr=on}}

| feedwaterheater = 4{{frac|1|4}}-BL Worthington

| builder = Baldwin Locomotive Works

| serialnumber = 60866–60869, 60884–60889, 60952–60957

| builddate = July–September 1929

| totalproduction = 16

| firstrundate = August 16, 1929

| retiredate = 1955

| disposition = All scrapped

| fleetnumbers = 4110–4125

| whytetype = 4-8-8-2

}}

Southern Pacific Railroad's AC-5 class of steam locomotives was the railroad's second class of 4-8-8-2 cab forward locomotives. They were built between July and September 1929 and placed in service soon after construction. The AC-5 class was only slightly larger than the AC-4 class.

The first locomotive of this class, number 4110, holds the dubious honor of being the first 4-8-8-2 cab forward locomotive to be scrapped when it befell this fate on February 3, 1953, at the railroad's Sacramento, California, shops. The rest of the class were removed from service and scrapped by mid-1955. None of this class was preserved.