While a crown corporation, Canadian National benefited from rather unique fiscal circumstance. Unaccountable to share holders, the railway could deploy monies to discretionary endeavours, such as Research and Development, without undue monetary scrutiny. Not that this was unfruitful. Via R&D CN developed the industry standard locomotive ‘Safety Cab’ and played a significant role in the creation of traction control (see the CNRHA book CNR Diesel Locomotives – Vol. II). Another optional expenditure: locomotive rebuilding. While most Class One roads engaged in motive power remanufacture, CN’s were among the most extensive, in both volume and scope. Best known is the GP9RM rebuild program. The elaborate remanufacturing process more than doubled the life of a couple hundred of Dick Dilworth’s masterpieces. Not nearly as numerous, but perhaps more drastic appearance wise was the SW1200RM, or ‘SWEEP’ (as the unit was affectionately known). Seeking to create a more capable/reliable switcher, PSC upgraded the prime mover (567C to 645C/1300 HP), improved cooling by grafting a GP9 hood (switcher type cooling via belt driven fans had long been a maintenance headache), and enhanced cab creature comforts (insulation/heating/hot plates/refrigerator). For more details see pages 170 – 171 of CNR Diesel Locomotives Vol. II. Only eight SWEEP’s were completed; CN ultimately decided to remanufacture a small group of SW1200RS’s in kind, and deploy 7000/7200 series GP9RM’s into yard service (often with accompanying slugs).
|No. 7106 was originally constructed as CN 1257 at the beginning of 1957. Similar to the balance of the ‘SWEEP’s’, the modified unit would join the Savage contract switching fleet as SVGX 7106.|
CN 7102 was delivered from GMD London in May of 1956 as SW1200RS CN 1230. Post CANAC ownership the compact unit would be acquired by Savage Inc. (www.savageservices.com) to join their contract switching fleet. Increased cooling capacity provided by the GP9 hood style radiator and fans provided for a HP increase to 1,300. Similar to the GP9RM, the inoperative dynamic brake geometry was redeployed as air intake and fitted with filters.