GP7 Details

Background
Canadian National began ordering General Purpose (GP) diesels later than many other North American railroads and as a result only purchased 24 GP7s. Later, in October 1958, GMD rebuilt wrecked F3A 9005 (originally built in 1948) with a GP9 carbody to give a GP7M 4824.
The first order (C-168) was for 20 dynamic braked GP7s which came equipped with Pyle headlights and Blomberg trucks as seen in the builder’s photographs above. A second order (C-169) for four GP7 without dynamic brakes followed but this was treated by GM as part of the initial order. All were built in the Fall of 1953 by GM in London, Ontario. Originally, the units were numbered 7555 to 7578 but in September 1954 they were renumbered to 1700 to 1723 and reclassified; then in June 1956 they were renumbered again to 4350 to 4373 and finally in August 1957 they received their final numbers 4800 to 4823.
Many were transferred to CN’s Western Region and some, if not all, received Flexicoil trucks for operation on prairie branchlines and the Alberta Resources Railway to Grande Cache. The Blomberg truck has prominent lateral leaf springs, supported by outside hangers, which help to reduce the side-to-side motion. These trucks have a wheelbase of 108 inches. Flexicoil trucks lack the outside spring hangers (and presumably the springs) and those used by CN have a wheelbase of 96 inches. A GP7 with Flexicoil trucks weighs 239800 lbs whereas with Blomberg trucks it weighs 246530 lbs. Presumably, because the locomotives were used on branchlines where speeds are generally lower, it was not necessary to provide as much lateral damping.
All units were retired between 1967 and 1975.

Liveries
All units were delivered in the green and yellow paint scheme (CNR Green No 11 and CNR Yellow No 11) initially with the CNR monogram (white CNR on red maple leaf with an outside diameter of 28 inches as seen in the in the builder’s pictures above and in the photo of 4357 in Canadian National in the West Volume 4 page 18 by J.A. Love and R.A. Matthews BRMNA (Calgary)). Many, possibly all, units later received the 1954 monogram in which yellow Canadian National Railways replaced the white CNR and the outside diameter was only 20 inches as seen in the photos of 4818. From the early 1960’s units began to be repainted in the CN orange and black scheme (CN Orange No 11, CNR Grey No 17 and black) with the CN symbol but three units were retired without being repainted into this livery — 4809 and 4812 (in 1971) and 4818 (in 1975) — information from Don McQueen and Ray Corley.
Modifications
Several visible changes were made to the units during their lifetime. After a couple of years the handrails on the frame side of the steps were sloped inwards to provide a better hand hold when walking around the step well. Some units had their exhaust stacks extended and later spark arresters were added, probably to all units. The three photos on page 35 of Rail Canada Volume 1 show these variations. At least one unit received a dual headlight, on at least one end, by August 1970 (see photo of 4818) and 4824 may have had dual headlights since its rebuilding. 4819 is believed to be the only unit fitted with a passenger style pilot. (see CNLines V3/3)
Flexicoil trucks from 4100-4133 were fitted beginning in early 1967 (Mod.HQ-8081). By November 1969 all units were listed in the Mechanical Dept. diagrams as having Flexicoil trucks (information from Don McQueen and Ray Corley). If this was indeed the case then several units were refitted with Blomberg trucks after only a few years as shown by the photographic evidence.