STEAM LOCOMOTIVE PM 706
In the immediate post-war period the Western Australian Government Railway was desperately short of locomotive power and there was a huge backlog of repairs deferred from the war years. By 1948, 143 of the 422 engines available, were out of traffic for repairs and a major shortage was pending. To overcome these problems the WAGR decided to build twenty-five new engines designated to be the Pm class
At the time,
the Midland Workshops were not in a position to build the required locomotives,
so an order for the twenty-five new locomotives was placed with the North
British Locomotive Company of Glasgow, Scotland and subsequently the purchase
number was increased to thirty-five. This company had previously built the
original P class locomotives in 1924. Nineteen engines had plain bearings on the
coupled axles and roller bearings on all carrying axles. The other sixteen were
fitted with roller bearings on all the axles and were classified Pmr, although
in most other details, they were very similar to the Pm engines. The gaps in the
frames were designed to accommodate either plain or roller bearing axle boxes
and one engine was later converted to a Pmr at Midland.
The chief mechanical engineer, Mr F. Mills had specified several modifications in addition to the roller bearings. The enlarged steam passages between steam chest and cylinders, the end covers incorporating the exhaust ways, the Y-form spokes on the coupled wheels and the plain, unfluted coupling rods were features included on this class of locomotive. An outside extension of the frames behind the rear coupled wheels supported the firebox and allowed an ash pan of greater capacity than that of the Pr to be provided, with unrestricted air flow to the grate. The rear frame extension incorporated curved horn guides for the roller-bearing radial axle boxes, which were tied together by plate framing, with side control springs behind the truck frame.
Click thumbnail for Drawing Of Pm - Pmr locomotives
New features introduced were the Cardew cylinder pressure relief valves, vacuum operated sanding gear and Hadfield steam-operated power reversing equipment, mounted below the right hand running board. The Pm class were the first locomotive for the WAGR to be fitted with power reversing equipment.
The Pm and Pmr classes entered service in the 1950s and were tested on fast passenger and goods traffic, and for a while they hauled the “Westland” between Kalgoorlie and Perth. However they seemed to be rigid at high speed and they were unable to maintain passenger service speed. Compensated springing was installed on the coupled wheels to improve the locomotive, however this modification produced no significant improvement, and as a result a speed restriction of 40 M.P.H. was imposed. This locomotive was relegated to goods and fast goods services.
The Pm and Pmr classes operated out of Northam and Merriden and over the Eastern Goldfields railways and their branches respectively. They saw service between Perth, Bunbury and Collie. With their free steaming boilers and large diameter coupled wheels they performed strongly throughout their service.
Pm 706 was saved from the scrapers torch and was purchased by the Narrogin Apex Club and placed on display undercover in the Allen Shepherd Memorial Park near the Narrogin railway station. After negotiations in 1988 the Apex Club agreed to make a long-term lease of the locomotive to HVTR so that it could be returned to active steam service. Many hours were spent by the engineering crew and careful restoration saw the engine re-enter service on the 20th May 1990 when together with W 908, they hauled the “British Car Day” tour train to Gingin. This locomotive was named “Narrogin” in recognition of the town that saved it
Pm 706 is a popular locomotive with rail enthusiasts with its large diameter wheels and specific beat of the cylinders making an impressive sight and sound.
This year (2002) Pm 706 was painted red all over with the words “Hotham Valley” in yellow lettering printed on the tender. This was done to launch the increasingly popular “Wizards Express” train, which is a regular tour throughout the school holidays from May to October. Quite a different look than the original Larch Green colour scheme when introduced in service with the WAGR!
Pm 706 is a regular performer on mainline tour trains throughout the steam season, however this particular locomotive is not permitted to operate on the railway between Alumina Junction-Dwellingup-Etmilyn sections due to its heavier axle loading than the W Class locomotives which were designed for these lightly laid lines.
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