NEW ZEALAND RAILWAY STEAM 4




The Palmerston North depot was home to a quota of locomotive classes “K”, “Ab”, “A”, “Aa” and “Bb”. There were Daily visits of “Wabs” and the occasional “X” from Taihape. In my second year through 1939 in Palmerston North the stable was joined by the new “Ka” and “J” class locomotives. Counting the Taihape “Wg” and the new “Kas” and “Js” I worked on ten classes during my relatively brief stay on the NZR. The following chart gives some vital statistics of those. In my time all except the “Wg” were superheated. The “As” and “Xs” were four cylinder compounds. Some of both classes were rebuilt as simple expansion after WW2 but I had moved to other fields.



Class Number built Years built Wheel arrange-ment Weight Tons Cylinders B & S

Inches Wheel

Dia.

Inches Grate

Area

Sq. ft. Boiler

Press

PSI Tractive

Effort

85% BP

Pounds

A 58 1906-1914 4-6-2 78.2 12 x 22

19 x 22 54 30 225 21250

X 18 2907-1915 4-8-2 94 13.5 x 22

22 x 22 45 37.1 230 29168

Wg 20 1910-1912 4-6-4T 50.5 14 x 22 45 16.9 200 16289

Aa 10 1914 4-6-2 88.7 18 x 24 49 33 180 24280

Bb 30 1915-1918 4-8-0 69 17 x 22 42.5 16.8 175 22253

Ab 141 1915-1925 4-6-2 84.7 17 x 26 54 33 180 21289

Wab 30 1917-1927 4-6-4T 71.5 17 x 26 54 33 200 23655

K 30 1932-1935 4-8-4 140 20 x 26 54 47.7 200 32740

Ka 35 1938-1950 4-8-4 145 20 x 26 54 47.7 200 32740

J 40 1939-1940 4-8-2 110 18 x 26 54 39 200 26520



I have mentioned some of the characteristics of the 1930s “K” and the earlier “X” class locomotives. In between these were various vintages well represented in numbers for a system the size of that operating in New Zealand. Still in service into the near final days of steam were 58 “A” class compound Pacifics built from 1906 through to 1914. Like their contemporary freight hauling “Xs” they were DeGlen compounds. Inside HP 12” X 22” cylinders drove the cranked front axle and outside LP 19” x 22” cylinders drove the second set of wheels. They had 4’- 6” diameter drivers and with the inside and outside cranks on each side arranged 180 degrees apart rode remarkably well at express speeds. As with the “X” class engines there were separate sets of Walscheart”s valve gear for the HP and LP cylinders adjusted by separate reversing levers. The drivers usually worked them with the HP lever notched up slightly closer than the LP lever. Some drivers even left the LP valves at full travel. Operation of the levers on the “As” was reasonably light but adjustments on the “Xs” required a man’s full strength. When topping a grade to avoid shoulder and back injury the drivers tripped the latch and let them go clunk to the front of the quadrant, then it was one foot braced against the quadrant to haul them up to resume steaming. They were hard work when used for yard shunting and train marshalling.