New Zealand Government Railways 4-6-0 Locomotives in New_Zealand


Class Details by Steve Llanso of Sweat House Media

Class U (Locobase 5184)

Data from John Garner and his comprehensive website [] (October 2002).

Garner notes that these Ten-Wheelers were less successful battling the Northwest Wind on the Canterbury Plain than had been hoped "although satisfactory in calm weather." They were eventually moved to Southland for branch-line operations and switching duties.


Class Ua (Locobase 5185)

Data from John Garner and his comprehensive website [] (October 2002).

In size these were repeats of the locally built Us of five years earlier, but with lower drivers. They later were refitted with superheated boilers.


Class Ub (Locobase 2706)

Data from John Garner and his website [] (October 2002). Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 21, p. 221 and Volume 23, p. 124. Works numbers were 16049 in November 1898; 16042-16048, 16050-16051 in December; 18574-18583 in June 1901.

These US-built locomotives handled the Christchurch-Dunedin expresses quite capably, even if some critics disliked the firebox separating the two crewmembers. (In the United States, such an arrangement was outlawed before too long.) Belpaire boilers and typical North American layout characterized all 20 engines, but the ten delivered in 1901 used Walschaerts valve gear to drive piston valves.

The first batch arrived in November and December 1898. They were numbered in order of their works numbers, the series running 278-287. The second batch -- 328-337 -- all arrived in June 1901.

All of the first batch were retired in the mid-1930s, 287 leading in June 1933 and the 280 going in September 1936. Three of the second batch -- 328, 333, and 334 -- were withdrawn in March 1935. The next to go was 335 in June 1953 with four more in March 1955 (331, 332, 336, 337) and the last two in January 1957.


Class Ub (Locobase 4084)

Data from "Brooks Ten-Wheel Passenger Locomotives for the New Zealand Government Railways", Railroad Gazette, Volume 33, No. 40 (4 October 1901), p. 678. Works number was 3925 in August 1901.

This was a larger engine than the Ucs delivered in the same year by Sharp, Stewart although they had the nearly the same power dimensions. It was an elegant locomotive with clean British lines and a well-shaped Belpaire firebox.

It was the only one of its type, according to John Garner and his website [] (October 2002, last accessed 9 February 2017) although Baldwin delivered 20 very similar, but slightly smaller, engines (see Locobase 2706). Garner reports that upon its arrival, the Brooks engine "was the largest and most powerful 'Ten-wheeler' in New Zealand."


Class Ub (Locobase 20150)

Data from "Ten-Wheeler for the New Zealand Government Railways", Railway & Locomotive Engineering, Volume 14, No. 11 (November 1901), p. 494. See also John Garner's , last accessed 9 February 2017 at "Class Ub 4-6-0" [] . Works number was 3275 in 1901.

The US-origin R&LE began its account of the single locomotive described with a bit of stars-and-stripes flag-waving: "With all the disparaging remarks made by our English friends against the American locomotive, we find that foreign countries still keep ordering them, and we also find that the tendency is to take the pure and simple American locomotive instead of the hybrid which it was the custom to specify a few years ago,"

R&LE went on to describe the British and British colonies' railways preference for copper fireboxes and either brass or copper tubes as "a fad" (...instead, Locobase suggests, of a reasonable choice based on decades of service). The steel Belpaire firebox in the new Ub variant joined with iron tubes in a test case for those materials.

Despite the boost from an American journal, the Richmond engine turned out to be a dud according to John Garner's website. It was, he reported, known as a "poor steamer." (Having called out the R&LE for its bias, Locobase now gives equal time to the skeptic who might argue that the crews responded more to the alien materials than to the engine's actual capability. For one thing, it was smaller than the Brooks engine (Locobase 4084) that was so well regarded.)

Its retirement in October 1933 was one of the first in the Ub class.


Class Uc (Locobase 2707)

Data from John Garner's [], last accessed 7 September 2008. See also the Midland Railway Heritage Trust website at[]

An interesting example of a British engine of this vintage using Walschaerts valve gear on piston valves. These operated on the South Island and were the slightly larger follow-ons to the popular Class Us.

But Garner's comment reveals the mediocre quality of this design" "With less adhesive weight, the 'Uc' was apt to wheel-slip badly, and it was a "great coal-scoffer" and not easy to fire."

According to the MRHT, which has preserved two of the engines, attempts to remedy the problems in the late 1920s by fitting seven of the class with superheated boilers was a "mistake". "The smaller U type superheated boiler reduced the grate area and firebox heating surface which then along with the larger cylinders made them hard to steam, particularly on long runs."

The saturated-boiler engines were written off in 1934-1936. The seven reboilered engines remained in service until the mid-1950s "hauling the Hokitika Express to Greymouth to connect with the Greymouth to Christchurch Express and also hauling and banking fully loaded coal trains from Reefton up over the well know Reefton Saddle and through the tunnel and down to Tawhai." But they were never well-liked by their crews.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassUUaUbUbUb
Locobase ID5184 5185 2706 4084 20150
RailroadNew Zealand Government RailwaysNew Zealand Government RailwaysNew Zealand Government RailwaysNew Zealand Government RailwaysNew Zealand Government Railways
CountryNew ZealandNew ZealandNew ZealandNew ZealandNew Zealand
Whyte4-6-04-6-04-6-04-6-04-6-0
Number in Class962011
Road Numbers278-287, 328-33717371
Gauge3'6"3'6"3'6"3'6"3'6"
Number Built962011
BuilderNZGRSharp, StewartBurnham, Williams & CoBrooksRichmond
Year18941899189819011901
Valve GearStephensonWalschaertStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)10 / 3.0510 / 3.0510 / 3.0510 / 3.0511 / 3.35
Engine Wheelbase (ft / m)21 / 6.4021 / 6.4020.92 / 6.3818.25 / 5.56
Ratio of driving wheelbase to overall engine wheelbase 0.48 0.48 0.48 0.55
Overall Wheelbase (engine & tender) (ft / m)42.10 / 12.8342.25 / 12.8842.67 / 13.0142.08 / 12.83
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)60,480 / 27,43360,704 / 27,53558,688 / 26,62064,500 / 29,25763,500 / 28,803
Engine Weight (lbs / kg)85,120 / 38,61085,568 / 38,81379,968 / 36,27391,500 / 41,50484,000 / 38,102
Tender Loaded Weight (lbs / kg)52,640 / 23,87753,760 / 24,38548,160 / 21,84557,000 / 25,855
Total Engine and Tender Weight (lbs / kg)137,760 / 62,487139,328 / 63,198128,128 / 58,118148,500 / 67,359
Tender Water Capacity (gals / ML)2280 / 8.642040 / 7.732040 / 7.732100 / 7.952000 / 7.58
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 3.40 / 3 4.40 / 4 3.90 / 45 / 54 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)34 / 1734 / 1733 / 16.5036 / 1835 / 17.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)54 / 137249.10 / 124749 / 124550 / 127049 / 1245
Boiler Pressure (psi / kPa)160 / 11175 / 12.10200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)16" x 20" / 406x50816" x 20" / 406x50816" x 20" / 406x50816" x 22" / 406x55916" x 22" / 406x559
Tractive Effort (lbs / kg)12,895 / 5849.0815,511 / 7035.6817,763 / 8057.1719,149 / 8685.8519,540 / 8863.21
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.69 3.91 3.30 3.37 3.25
Heating Ability
Tubes (number - dia) (in / mm)177 - 2" / 51220 - 1.75" / 44165 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)13.37 / 4.0812.60 / 3.8412 / 3.66
Firebox Area (sq ft / m2)8789.70 / 8.3491 / 8.4594 / 8.73
Grate Area (sq ft / m2)16 / 1.4916 / 1.4916 / 1.4916.70 / 1.5516.10 / 1.50
Evaporative Heating Surface (sq ft / m2)972 / 90.33972 / 90.331321 / 122.771351 / 125.511131 / 105.07
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)972 / 90.33972 / 90.331321 / 122.771351 / 125.511131 / 105.07
Evaporative Heating Surface/Cylinder Volume208.84208.84283.83263.89220.91
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation25602800320033403220
Same as above plus superheater percentage25602800320033403220
Same as above but substitute firebox area for grate area13,92017,94018,20018,800
Power L14353621058795108
Power MT476.03699.84602.84532.03

Principal Dimensions by Steve Llanso of Sweat House Media

ClassUc
Locobase ID2707
RailroadNew Zealand Government Railways
CountryNew Zealand
Whyte4-6-0
Number in Class10
Road Numbers
Gauge3'6"
Number Built10
BuilderSharp, Stewart
Year1901
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)10
Engine Wheelbase (ft / m)21.25
Ratio of driving wheelbase to overall engine wheelbase 0.47
Overall Wheelbase (engine & tender) (ft / m)42.50
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)60,032
Engine Weight (lbs / kg)85,344
Tender Loaded Weight (lbs / kg)54,880
Total Engine and Tender Weight (lbs / kg)140,224
Tender Water Capacity (gals / ML)2040
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)33 / 16.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)49 / 1245
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)16" x 22" / 406x559
Tractive Effort (lbs / kg)19,540 / 8863.21
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.07
Heating Ability
Tubes (number - dia) (in / mm)
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)91
Grate Area (sq ft / m2)17 / 1.58
Evaporative Heating Surface (sq ft / m2)975 / 90.61
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)975 / 90.61
Evaporative Heating Surface/Cylinder Volume190.44
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation3400
Same as above plus superheater percentage3400
Same as above but substitute firebox area for grate area18,200
Power L14562
Power MT502.61

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