CLASS: U Switcher Type 0-6-0.

Taken from Spanner Magazine, Collectors' Item - 8 by Omer Lavallée

The fact that its functions were largely performed out of the public eye does not diminish in any way the role which the switcher or yard-engine plays in rail operations. Since its design characteristics depended upon power and hardly at all on speed, it was determined, at an early stage in locomotive development, that the ideal locomotive was one in which its entire weight was available for tractive effort. Hence, the true switch engine was equipped neither with pony or trail ing truck and as a consequence, its aesthetics suffered accordingly, when compared with sleek and racy passenger locomotives, or heavy and powerful freight engines.

By far the most popular wheel arrangement as far as North American railways were concerned, was the 0-6-0. Canadian Pacificpossessed about 250 of these locomotives, most of them built' in the Company's own shops in Montreal, as No. 2170 (later 6170) was in 1906.

To the yard engine fell the job of breaking up trains after their arrival in terminal and forming them again into new trains for different destinations. They were also in use at large terminals in "transfer" service, moving cuts of cars from one railway yard to another, or picking up or setting off cars destined from or to customers' spur tracks. The yard engine played a most essential part in the sequence of train operations, and is entitled, accordingly, to its own distinctive niche in any locomotive "hall of fame".

Of the 195 type 0-6-Os of class U-3, 99 were saturated locomotives, with flat valves, while the remainder were superheated, with piston valves.