I often wondered. I was out on the Oregon cost in Toledo or. The PNWR Toledo Hauler came in. It was a rainy fall day and the Radiators on the GP40s and GP39-2s were coated in leaves. the line to Toledo is runs through the well forested cost range and so this isn’t a surprise, but was wondering how much of a reduction in effectiveness those leaves entailed. would they require the crew to clean before leaving? And then there are the rails. I know that train sometimes has to double the hill due to traction, but not sure the effectiveness of the loco with a leaf covered radiator.
Water from a tank to spray on the radiator probably came from a surface or ground water supply that would contain dissolved solids that may form scale on the radiator. Rain water might contain some dust, but generally contains less solids.
The big change to increase the cooling system performance starting with the SD50 was increasing the height of the intake shutters from 24 to 30". This not only reduced the pressure loss thru the intake screens and shutters but also provided an improved airflow path thru the radiators. After that, there was no effort to design a cold side fan system like the T-2 models.
Dave
I believe the tunnels encountered ty the SP and other buyers of ‘Tunnel Motors’ had much longer tunnels on the railroads that do NS & CSX. Longer tunnels raise the level of heat as the train proceeds through the tunnel.
Any water to be sprayed in the Rad system more than likely had an additive to preclude scale buildup.
Your’re correct the SD45’s only had the water spray system. I had my units mixed up.
To me, the idea of a B-B tunnel motor just doesn’t make sense. We’re talking about rugged terrain with plenty of snowsheds and tunnels, with slow running - ie: C-C territory.
Surprisingly, it took a relatively long time for the industry to come around to the benefits of a fully powered three axle truck. The SD-40 was the first of the high production locomotives with a pair of three axle powered trucks - it began production in 1966. Four axle locomotives ruled all forms of service prior to the SD-40.
I don’t know why, however, I suspect it took time for engineers to develop a three axle truck that worked without over stressing the track structure, have suitable ride qualities, have a good maintainability.
I don’t even think the logic makes sense. Western Pacific, Santa Fe and for that matter, Rio Grande in some cases, used plenty of 4 axle power through tunnels and they also ran plenty of fast trains.
4 axle units are fine as long as you power your trains to maintain 25-30 mph or more at all times. Below that they start having real problems with slipping, even with the Positive Traction Control that EMD developed for the GP40-2 and later units, I believe the test units were CN GP40-2L’s on loan to Rio Grande (while the wheelslip control was obviously quite successful, I bet DRGW was not impressed with their lack of dynamic braking).
6 axle units not only produce far more tractive effort at lower speeds, they also provide much more dynamic braking effort at all speeds.
A lot of carriers didn’t see any benefits to Dynamic Braking and did not order it to be installed on their locomotive purchases.
Brakes? They only slow you down.[/sarcasm]
But Rio Grande was not one of them. Didn’t they buy PA’s instead of E’s in large part due to their DB capability?
CN actually disabled the DB on some early units that had been delivered with it, and kept ordering road power without DB until it became a standard feature on new units during the 1980s.
MoPac, Rock Island, Northwestern and Illinois Central were other notable anti-DB holdouts.
My impression is that the Rio Grande didn’t run drag freights as often as say the Southern Pacific did. So they seemed willing to forgo the benefits of C-C power like increased low speed tractive effort for much of their traffic, remaining a 4 motor GP advocate right until the end.
One thing to keep in mind with this time, is the rise of the micoprocessor and other advanced onboard electronics and the many promises the builders made based on the benefits they offered. EMD for instance advertised a 33% increase in “hauling capability” for 50 series locomotives compared to their Dash 2 predecessors.
If you read literature from the time for things like EMD’s Super Series wheel slip control and such, it helps shed some light on what the Rio Grande’s line of thinking may have been with their interest in an advanced high horsepower B-B with a cooling system tailored for hard running in tunnels.
Rio grande also had (and the route still has) the problem that their route is less desirable than the Transcon to the north. A drag freight is going to prefer going through the Wasatch. Rio Grande wanted to take advantage of their “potentially” faster route. Especially prior to the MP being pulled up.
Note that all of these roads were generally level with few to no heavy grades. The practice of using D/B to control speed on level track had not yet been developed. As an aside, C&NW was noted for its SD45’s without d/b.