What was the purpose of the Draper Taper bodies in Canada, and the cowl bodies in the U.S.? A few railroads had the F45/FP45, but the design wasn’t around for long. Then there were the orders for the SD40F-2 and SD50/60F. Again, the design didn’t stay around for long, as all railroads went back to the standard hood units we have today.
Why didn’t any of the U.S. roads try the Draper Taper? They’re interesting units, but I’m curious as to why they were developed and why that design didn’t last.
Also, why didn’t any of the U.S. roads try the Canadian Safety Cab? EMD eventually gave the ugly three window design to us on the SD60M, before coming up with the two-window design around 1990 - 15 years or so after the 4-window design for up north.
One reason for the full-width cowl on Canadain units is the weather. It allowed them to work on the units outside when necessary despite the harsh winters.
CN stopped ordering cowls because of the addition cost. Perhaps they would still be acquiring them if the cost was equal.
Also, why didn’t any of the U.S. roads try the Canadian Safety Cab? EMD eventually gave the ugly three window design to us on the SD60M, before coming up with the two-window design around 1990 - 15 years or so after the 4-window design for up north.
The U.S. roads did try the Canadian Safety Cab. P&W bought 5 M420Ws during 1973.
ATSF borrowed CN SD50F 5456 during October 1988 for a Chicago-LA round trip to evaluate the design and ordered SD60Ms with some changes.
CP received the SD40-2F locomotives also during October 1988 with 3 windows.
The Draper Taper was only a minor modification of the cowl carbody to provide rearward visibility for the engine crew.
The cowl carbody enabled engine crews to walk between units without being exposed to weather, to avoid snow accumulation on walkways, and to give a more streamlined and more modern-looking appearance. From a maintenance perspective the cowl carbody was awful, because it restricted working room, made it hard to see things, and made it hard to haul tools and parts in and out. Yes, you could remove it but that takes significant time and labor, and that’s money not only to undo all the bolts, coolant piping, wiring harnesses, etc., plus lost availability on the unit while it sits in the shop. The advantages were difficult to quantify whereas the disadvantages where eminently quantifiable – all you had to do was look at the maintenance cost and availability of a standard SD45 versus an F45.
You didn’t have to be a genius to predict back in the 1960s that the cowl carbody was never going to be very popular.
Canadian Safety Cabs were cramped and the units rode poorly because of all the extra weight up front, especially a GP40W. GP40s are pretty bouncy to begin with and the GP40W is very unpleasant on poor track. The redesigned M cab is much better.
Part of the reason for no more Draper Tapers is that Mr. Draper (CN’s head of motive power) retired. They then went to the stock engines and saved some money, easier to work on, etc.
Some of UP’s Canadian cab style SD60Ms came with a curve to the top end of their noses. It had something to do with improving the forward visibility for the crew. EMD eventually switched to the F45-style cab for its SD60M, SD70M, SD70MAC, SD75M, SD80, and SD90 models. Burlington Northern rostered Canadian cab SD60Ms, plus SD60s with the F45-style cab, and Soo Line owned a handfull of SD60Ms with the Canadian cab.