NZR UB class explained

NZR U^B class
Powertype:	Steam
Builder:	Baldwin Locomotive Works, Brooks Locomotive Works, Richmond Locomotive Works
Builddate:	1898, 1901
Totalproduction:	22
Whytetype:	4-6-0
Driverdiameter:	49.1253NaN3
Weightondrivers:	26.41NaN1
Locotenderweight:	57.81NaN1
Fueltype:	Coal
Boilerpressure:	1750NaN0 (1898) 2000NaN0 (1901)
Firearea:	16square feet
Totalsurface:	1324square feet
Cylindercount:	Two, outside
Cylindersize:	16x
Tractiveeffort:	145902NaN2 (1898) 166702NaN2 (1901)
Operator:	NZR
Disposition:	Withdrawn

The NZR U^B class were a series of Ten Wheelers built by American manufacturers for New Zealand Railways (NZR) around the start of the twentieth century. Two batches were built by Baldwin in 1898 and 1901 (ten each). The earlier engines had slide valves and inside Stephenson motion, the later had piston valves and Walschaerts valve gear, as well as a higher boiler pressure. Two additional locomotives were obtained in 1901 from ALCO, one each from Brooks and Richmond.

• The Brooks locomotive (#17) was heavier (30.1 long tons adhesive weight) with attendant increase in tractive effort (18340 lbf), and had a larger grate (17 sq ft). This locomotive was very popular with crews. This locomotive was dumped on the Oamaru foreshore.
• The Richmond locomotive had less evaporative heating surface but included a superheater. Boiler pressure was lower (180 psi) and tractive effort was marginally lower.

The locomotives were initially assigned to Dunedin to Christchurch expresses and were reassigned as newer power replaced them. The last assignment for the class was on the West Coast Region.

See also

• NZR U class
• NZR U^A class
• NZR U^C class
• NZR U^D class
• Locomotives of New Zealand