CNR's GP-9's - Part II The GP-9RM's

In my previous entry, I described the Canadian National Railways first series of General Purpose – GP-9’s. Big mistake! It was never my intention to give the detailed history of CNR’s GP-9’s. It is just that one thing lead to another, and suddenly I was in over my head!

In later years, many or these units, with god only knows how many miles on them, were sent to CNR’s Pointe St. Charles shops near Montreal Quebec for upgrading, a new lease on life. By some accounts – yet to be verified – some 246 units were involved in this rebuild effort over a few years, as funding was made available, resulting in the GP-9RM.

Tim Ball captured a great side view of CN 7080 at Brantford, ON., Dec 2006

Major items on the “to do list” included:

• Removing the prime mover 1,750 hp GM 16V-567C and installing the GM 16V-645C motor, rated at 1,800 horsepower. The newer motor now available from General Motors provided a slight increase in horsepower with a turbocharger, while removing the Roots gear driven supercharger.
• Removing the dynamic braking system, including resistance grids and roof mounted 48” fan. The familiar “blister” was retained, behind which, if you look carefully at Tim Ball's featured photograph, you can see the grill-work for the improved air filtration system.
• Improvements to the cab interiors and installation of radio equipment to allow so called “Beltpack” or “crew-on-the-ground” remote control. (And boy, didn’t THAT create some interesting news items!)
• And the obvious lowering – chopping, if you like – the short hood, for increased crew visibility. Not for running ahead, mind you, they retained “long nose forward running” configuration, but for backing up!

These are the major upgrades, as I understand them. I did not say “complete” list, so if you can ad or comment on this program, use the “Comments” box at the end of the story.

I think that once you move beyond the “as manufactured” locomotive types into the murky world of rebuilds and re-powering, you enter shark-infested waters. In the end, only the railroads themselves know the reasoning behind model designations, and it isn’t to make life easy for rail fans.

Many times, I find more enlightened and complete information about motive power from “model” railroad enthusiasts as opposed to “prototype” enthusiasts. This I attribute in part to their almost obsessive attention to details. In the end, the model railroader came though, in spades concerning the RM!

Even though you may not be a "modeler," this issue of the National Model Railroad Association Southeastern Region Newsletter, published in the summer of 2008, proved to be helpful in explaining what an RM is. The article begins on page 9:

NMRA-SER-S2008 (6,402K)

So just about the time I thought I got it figured out (and I’m not even going to get involved with the GP-7RM’s, or the F7AU’s!) along comes the GP-9u.

And then there is the GP-9R. I read one fellows accounting of what a “GP-9R” was. He simply said, “They chopped the short nose down. " Yet another said, “Nah! It means ‘reconditioned.’”

Well, would that not be an “RM” or “u?”

And then there are the SWEEPS!

Bottom line, terminology, abbreviations, acronyms, without definition is worthless.

Looking forward to receiving informative comments below!

Railroad Stuff: Canadian National 7080RM. Built Canadian National Railways 4121, by GMD in September 1957, serial number A1283, 1,750 horsepower. Renumbered CN 4377 in 1984, renumbered CN 7080RM in 1993.

Photo courtesy, Tim Ball.