CLASS: S1a-S1c Shay Geared Type 4-4-4.

Taken from Spanner Magazine, Collectors' Item - 10 by Omer Lavallée

This locomotive is representative of a collateral development of the conventional railway engine, known as the "geared locomotive". As as it's name suggests, the transmission of the motion initiated by the cylinders is taken to small driving wheels through gearing, resulting in a much higher power/weight ratio than in a conventional locomotive, admittedly at considerable cost in speed. The geared locomotive as it has evolved in North America comprised a locomotive frame mounted on two or three four-wheel trucks, upon which a steam-driven drive shaft is placed longitudinally along the locomotive, the driving axles on the trucks propelled by this shaft through gearing.

The manner in which this drive shaft is arranged Nith relation to the cylinders, however, creates three basic variations among geared locomotives of which the "Shay" type, illustrated above, was the most popular. It will be seen that the cylinders are in a vertical plane on the right hand side of the locomotive, driving vertically to the drive shaft. which is placed along the same side of the locomotive as the cylinders. The boiler is offset to the opposite side from the cylinders, to compensate for weight distribution. The popularity of the "Shay" locomotive was due in large measure to the ready accessibility of its cylinders, motion, crank shaft and drive shaft, simplifying minor repairs on the road when necessary.

The geared arrangement allowed the locomotive to accommodate itself to considerable irregularity in the track and negotiate much steeper grades than conventional locomotives. Thus it enjoyed its most extensive use in the logging industry, where cutting patterns in hilly terrain necessitated the laying of temporary spurs along the surface of the ground without ballast.

Canadian Pacific's Shay-geared locomotives, among the largest of their kind ever to operate in Canada, were built between 1900 and 1903 by the Lima Locomotive & Machine Company of Lima, Ohio, USA. Intended for main line use on the "Big Hill" east of Field, B.C., a few years' operation showed that in spite of a tractive effort about 50% greater than a D-10 class 4-6-0 locomotive, the Shays' effective top operating speed of about 15 m.p.h. was too slow for main line operation. They were gradually transferred to southern British Columbia where they worked on the mine spurs around Grand Forks and Eholt until retirement in the years immediately preceeding the First World War.