Would the GP50T have been longer than a regular GP50. Gary
This is PLI 92061. I think Dave Goding will have specific information on this.
I pretty sure it was to be the same length as a standard GP50 but I don’t have copy of the general arrangement drawing to know positively, at most it would have 37’ truck spacing - we always avoided anything closer to 39’ to avoid lining up with rail joint spacing. I do recall it was to have two 48" cooling fans similar to an SD40T-2 which the higher fan speed tied to 950 rpm engine speed made work. It had a standard 3 cyl water cooled compressor in the normal location to the rear of the equipment rack with a curved shroud over it to keep it inside the engine compartment.
Dave
Not necessarily, by doing a quick and dirty (eye-ball) check of Athearn’s BB SD40T-2 and GP50, the radiator sections are the same length. So, you could feasibly take the radiator section of the SD40T-2 and graft it onto the GP50 with no increase in length.
As I said, I believe it was the same length, however, it’s not the radiators that would drive the length, it’s fitting two cooling fans below the radiators between the air compressor and the rear sandbox while not obstructing the forward fan inlet too severely. The cooling system consists of two parallel sets of 3 double length radiator cores (54" long, 30" wide, 6 tube rows deep) with the fans biased to the rear two double length cores which may make the forward core less effective - the fans need to be as far from the radiators as possible to make full use of the core length. No doubt the cooling system engineer would have made a physical mock-up and tested it to insure design performance if an order materialized, but that never happened.
Dave
Stupid question: could these fan motors operate reliably if inclined slightly? Unless I misunderstand how the fans are located relative to the access doors, I would think there’s enough room with ducts above and below the fans to angle the forward one slightly even with ‘obtrusion’ into the intake space at the front.
Are there good available drawings that show the arrangement, or pictures with the fan inspection doors open?
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.
Thanks again!
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
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Peter
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
Here’s the sort of operating conditions that led to the development of the tunnel motor in the first place:
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 su
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.
Peter
I had never heard about the GP50T prior to this thread. What was the thinking of I guess Rio Grande here? Was it just that they wanted 4axle locos for higher speed service? ANd that begs the question why they didn’t ask for SD50T locomotives.
The N&W and SCL SD50’s that they had previously tested showed no tendency to derate themselves in tunnels.
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.
.
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.
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.
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