Public Works Department 0-6-0 Locomotives in New_Zealand

Class Details by Steve Llanso of Sweat House Media

Class Y (Locobase 5197)

Data from "Side Tank Locomotives for New Zealand", Locomotive Magazine, Volume XXIX [29], Volume 375 (15 November 1923). See also John Garner's comprehensive site at [] ... (October 2002); and "NZR Y class" in Wikipedia at [], last accessed 2 December 2021. Works numbers were 1443-1445 in July 1923 and later.

Hunslet's production record shows that "Capt Dansey" of the Public Works Department in Wellington ordered the this trio. According to Garner, these were the smallest engines to enter NZ service in the 20th century. Produced decades after the same builder's M class, these six-wheel tanks were about the same size. Changes included Walschaerts gear, higher boiler pressure, lower driver diameter.

After 15 years as PWD engines, all were transferred to the New Zealand Railways in 1938. Wikipedia notes their identification as a "splinter class" offering "very little useful capabilities on a modern railway." Consequently, the class served the Way and Works

as construction engines and later as rentable motive power for private industry.

544's "worn out boiler" led to its scrapping in 1957. 543 went into storage in 1958 and was sold for scrap to Pacific Steel in 1964.

542 evaded the ferro-knacker by being sold to Wilsons Portland Cement as their #3. Remaining on the books until 1985 kept it available for New Zealand Museum of Transport and Technology's Western Springs Railway as more heritage steam locomotives were preserved. Restored as Y 542, it hauled passenger trains as recently as 2021.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID5197
RailroadPublic Works Department
CountryNew Zealand
Number in Class3
Road Numbers542-544
Number Built3
BuilderHunslet Engine Co
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m) 9.50 / 2.90
Engine Wheelbase (ft / m) 9.50 / 2.90
Ratio of driving wheelbase to overall engine wheelbase1
Overall Wheelbase (engine & tender) (ft / m) 9.50 / 2.90
Axle Loading (Maximum Weight per Axle) (lbs / kg)19,488 / 8840
Weight on Drivers (lbs / kg)57,792 / 26,214
Engine Weight (lbs / kg)57,792 / 26,214
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)57,792 / 26,214
Tender Water Capacity (gals / ML)600 / 2.27
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 0.90 / 0.80
Minimum weight of rail (calculated) (lb/yd / kg/m)32 / 16
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)40 / 1016
Boiler Pressure (psi / kPa)160 / 11
High Pressure Cylinders (dia x stroke) (in / mm)13" x 20" / 330x508
Tractive Effort (lbs / kg)11,492 / 5212.69
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.03
Heating Ability
Tubes (number - dia) (in / mm)132 - 1.625" / 41
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m) 8.37 / 2.55
Firebox Area (sq ft / m2)52 / 4.83
Grate Area (sq ft / m2) 9.10 / 0.85
Evaporative Heating Surface (sq ft / m2)522 / 48.50
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)522 / 48.50
Evaporative Heating Surface/Cylinder Volume169.89
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1456
Same as above plus superheater percentage1456
Same as above but substitute firebox area for grate area8320
Power L12715
Power MT310.71

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Wes Barris