SD70Dude MoPac, Rock Island, Northwestern and Illinois Central were other notable anti-DB holdouts.
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.
BaltACD SD70Dude 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]
SD70Dude 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.
Greetings from Alberta
-an Articulate Malcontent
SD70Dude6 axle units not only produce far more tractive effort at lower speeds, they also provide much more dynamic braking effort at all speeds.
Never too old to have a happy childhood!
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.
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.
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.
Leo_Ames I've not heard that, but their SD45's were. Presumably if so equipped, the system worked similarly to what the SD45's had. I believe there are basic details about this at Don Stack's site (UtahRails) about the water spray system on the Rio Grande SD45's. Water would be sprayed onto the radiator cores by nozzles and at the rear of the long hood, there was a large water tank.
I've not heard that, but their SD45's were. Presumably if so equipped, the system worked similarly to what the SD45's had.
I believe there are basic details about this at Don Stack's site (UtahRails) about the water spray system on the Rio Grande SD45's. Water would be sprayed onto the radiator cores by nozzles and at the rear of the long hood, there was a large water tank.
Your're correct the SD45's only had the water spray system. I had my units mixed up.
MidlandMike M636C MidlandMike Overmod ...The water is sprayed thinly on the radiators (making as sure as possible not to thermally shock them) and flashes to vapor ... Does that cause scale to build up that might hamper heat transfer? No worse than running on a wet day. I would expect that on a wet day, a lot of water is sucked in the side vents and through the radiators. I would think leaves in Fall and dust in Summer would be a bigger problem. Peter 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.
M636C MidlandMike Overmod ...The water is sprayed thinly on the radiators (making as sure as possible not to thermally shock them) and flashes to vapor ... Does that cause scale to build up that might hamper heat transfer? No worse than running on a wet day. I would expect that on a wet day, a lot of water is sucked in the side vents and through the radiators. I would think leaves in Fall and dust in Summer would be a bigger problem. Peter
MidlandMike Overmod ...The water is sprayed thinly on the radiators (making as sure as possible not to thermally shock them) and flashes to vapor ... Does that cause scale to build up that might hamper heat transfer?
Overmod ...The water is sprayed thinly on the radiators (making as sure as possible not to thermally shock them) and flashes to vapor ...
Does that cause scale to build up that might hamper heat transfer?
No worse than running on a wet day.
I would expect that on a wet day, a lot of water is sucked in the side vents and through the radiators.
I would think leaves in Fall and dust in Summer would be a bigger problem.
Peter
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.
Any water to be sprayed in the Rad system more than likely had an additive to preclude scale buildup.
bogie_engineer Leo_Ames The N&W and SCL SD50's that they had previously tested showed no tendency to derate themselves in tunnels. 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
Leo_Ames The N&W and SCL SD50's that they had previously tested showed no tendency to derate themselves in tunnels.
The N&W and SCL SD50's that they had previously tested showed no tendency to derate themselves in tunnels.
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.
Spray cooling is very effective -- you see it used on one of the early British turboelectric locomotives to allow a physically much smaller condenser. The water is sprayed thinly on the radiators (making as sure as possible not to thermally shock them) and flashes to vapor abstracting a very high amount of heat. This also constitutes more efficient heat transfer than the liquid-to-air cooling of fan-forced radiators gives.
.
Rio Grande wanted power online quickly to deal with a traffic surge, so made a deal to take over some Chessie units that were already in production since the latter had a surplus of power and were willing to delay delivery until the next year (And Rio Grande couldn't wait).
So the Rio Grande SD50's arrived with few changes to Chessie's specifications and had features like the battery box covers with the slots that are associated with Chessie.
Didn't last long though and soon the Rio Grande had a lot of power stored. Wouldn't be surprised if that surplus of power, much of it in good shape, is what did in the GP50T. A lot of their GP40's for instance were idle by 1985.
While I have still not found a diagram, I have found external drawings of the JT26C and photographs of the left side of the JT26C-2SS. These show a narrow vertical grille at the No 2 end for the No 2 end pressurisation fan.
At this site:
BL Class Locomotive (auscisionmodels.com.au)
Scroll down to the photographs of real locomotives towards the end.
Only the first photo of loco BL32 (JT26C-2SS) in original condition shows the No 2 end pressurisation intake on the left side of the locomotive. Other photos of the left side show a blanking plate.
Given the size and shape of grille and its location, the logical fan arrangement is a vertical 48" fan in a partition just forward of the grille...
This should confirm Dave's recollection.
I note that the proposed models ALL lack the No 2 end pressurising fan.
About this time it was realised that the coventional dust filtration on standard EMD domestic USA locomotives met most dust exclusion requirements.
bogie_engineer Thanks Peter, I'd hope you respond. I distincly remember a Clyde loco arrangement drawing with a 48" fan on a vertical sheet but perhaps the EMD fan engineer had some reason not to do it so it was never built in that fashion. I know early production Q-fans, where the fan is beneath the motor, had bearing problems that required a beefed-up bearing to resolve so it could be the radial bearing capacity is inadequate for vertical mounting, as the bearing normally sees mostly a thrust load. Dave
Thanks Peter, I'd hope you respond. I distincly remember a Clyde loco arrangement drawing with a 48" fan on a vertical sheet but perhaps the EMD fan engineer had some reason not to do it so it was never built in that fashion. I know early production Q-fans, where the fan is beneath the motor, had bearing problems that required a beefed-up bearing to resolve so it could be the radial bearing capacity is inadequate for vertical mounting, as the bearing normally sees mostly a thrust load.
Dave,
My comment was really addressing Overmod's comment about tilting the fans.
My comments specifically addresed the forward pressurising fans of the locomotives concerned. All of these were designed with a rear pressurising fan as well. The forward fan pressurised the electrical compartment, and the alternator with a partition forward of the engine to keep oil out of the electrical gear. A second fan was needed to keep dust out of the engine compartment, auxiliaries and air compressor.
In the original locomotives, the first ten had only a single 36" fan at the rear which blew through a box structire of conventional oil bath filers. This allowed some oil to migrate forward into the electrical gear.
Locomotive eleven had the partition and a second fan buried inside the body draeing air theough body side vents separately pressurising the electrical gear. The "GM class" locomotives had no other vents in the body side except for the radiator ductiing. The change occurred in late 1952, early 1953 and all the locomotives were retrofitted.
In 1955, someone thought "if we remove the rear fan, we can do away with the partition and blow all the oil to the back of the unit". So GM12 and GM13 had two 36" fans on the roof forward of the engine. They thought about it enough tpo put a duct over the fans so that exhaust wouldn't be sucked in when the loco was running cab trailing. But this lasted only a couple of months and they reverted to the partition and front and rear fans. Strangely, there was no duct over either fan, both of which were on the roof.
The big GT26Cs were the next development, in 1967. These had fans at each end, the forward one as described at 30 degrees. I haven't been able to find drawings showing the rear fan. (I know I have one somewhere). These rear fans were fitted new from 1967 until 1981 (although the last four GT26Cs to the original design and ten with wide noses had no pressurising fans, relying on the EMD domestic unit arrangements of a central air intake)
The boxcabs, JT26C and Australian National's JT26C-2SS units still had rear pressurising fans, so until 1981 or so.
I think this was before Q fans, at least on export units.
But from 1981, the second batch of JT26C-2SS for Victoria lacked the rear prssurising fan, and these were removed from the Australian National units. I think they came off the 1967 GT26Cs at major overhauls also.
It is possible that these rear fans were sitting vertically in a partition. I just don't have any drawings to show this.
An article of mine on the first JT26C-2SS units appears in this month's "Australiam Railway History" which illustrates the rear air pressurisation intake on an AN unit and a drawing showing it blanked on the Victorian units.
But the fact that these were actively removed might imply that the fans didn't last in that location, which might be related to their mounting.
I'll keep looking for a drawing.
Here's the sort of operating conditions that led to the development of the tunnel motor in the first place:
https://m.youtube.com/watch?v=wXpTRpn_fuQ
bogie_engineer On the T-2's as well as the GP15 and MP15AC, the fans were all mounted to a horizontal sheet the same as when they are on the roof. The only non-horizontal application I can recall is some Clyde built locos that had a fan mounted to a vertical sheet to pressurize the carbody to the extreme for keeping out dust, probably used in Australia but not sure. In any event, I think the fan would be fine mounted on an angled sheet but it makes the fabrication of the hood more difficult. I do recall the GP50T arrangement had a divider sheet between the fans with an offset to the middle of the radiator bank to help the flow equalize across the radiators.
On the T-2's as well as the GP15 and MP15AC, the fans were all mounted to a horizontal sheet the same as when they are on the roof. The only non-horizontal application I can recall is some Clyde built locos that had a fan mounted to a vertical sheet to pressurize the carbody to the extreme for keeping out dust, probably used in Australia but not sure. In any event, I think the fan would be fine mounted on an angled sheet but it makes the fabrication of the hood more difficult. I do recall the GP50T arrangement had a divider sheet between the fans with an offset to the middle of the radiator bank to help the flow equalize across the radiators.
Angled radiator cooling fans were a feature of all of Clyde Engineering's cab units, except for the AJ16C which had a mechanical fan drive and the AT26C which had conventional 48" fans on a flat roof.
The diagram of the Victorian B class shows the arrangement.
B class diesel diagram (victorianrailways.net)
With the lower clearances required in Australia, there wasn't room for the ducting above the engine to allow the single row of four 36" cooling fans characteristic of the F3 and later units. So the fans were placed on the curve of the roof immediately above the radiator cores.
The forward pressurising fans on the Clyde GT26C, JT26C and JT26C-2SS were set at an angle of about 30 degrees under the air intake, forwad side low.. This was visible on the GT26C which had the lower side of the hood air intake vents angled to match the angle of the fan. These were 48" fans.
L 266 Kalgoorlie, 7001 - WAGR L class (diesel) - Wikipedia
Thanks again!
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