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gp50t
Posted by IA and eastern on Saturday, May 29, 2021 2:24 AM

Would the GP50T have been longer than a regular GP50. Gary

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Posted by Overmod on Saturday, May 29, 2021 7:43 AM

This is PLI 92061.  I think Dave Goding will have specific information on this.

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Posted by bogie_engineer on Saturday, May 29, 2021 10:38 AM

IA and eastern

Would the GP50T have been longer than a regular GP50. Gary

 

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 

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Posted by DanRaitz on Monday, May 31, 2021 10:13 AM

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.

 

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Posted by bogie_engineer on Monday, May 31, 2021 10:40 AM

DanRaitz

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

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Posted by Overmod on Monday, May 31, 2021 11:32 AM

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?

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Posted by bogie_engineer on Monday, May 31, 2021 11:57 AM

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.

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Posted by Overmod on Monday, May 31, 2021 12:50 PM

Thanks again!

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Posted by M636C on Tuesday, June 1, 2021 7:49 AM

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.

 

 

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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Posted by bogie_engineer on Tuesday, June 1, 2021 11:28 AM

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

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Posted by SD70Dude on Wednesday, June 2, 2021 7:26 PM

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

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Posted by M636C on Wednesday, June 2, 2021 10:56 PM

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

 

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.

Peter

 

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Posted by M636C on Saturday, June 5, 2021 2:43 AM

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

 

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Posted by YoHo1975 on Monday, June 7, 2021 11:18 AM
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.
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Posted by Leo_Ames on Monday, June 7, 2021 12:55 PM

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.

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Posted by SD60MAC9500 on Tuesday, June 8, 2021 4:15 PM
 

.

 
 
Rahhhhhhhhh!!!!
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Posted by Leo_Ames on Tuesday, June 8, 2021 10:15 PM

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. 

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Posted by Overmod on Wednesday, June 9, 2021 7:37 PM

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.

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Posted by MidlandMike on Wednesday, June 9, 2021 7:53 PM

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?

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Posted by M636C on Wednesday, June 9, 2021 11:54 PM

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

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Posted by YoHo1975 on Thursday, June 10, 2021 2:06 PM
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.
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Posted by MidlandMike on Thursday, June 10, 2021 6:48 PM

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.

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Posted by bogie_engineer on Thursday, June 10, 2021 7:32 PM

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

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Posted by BaltACD on Thursday, June 10, 2021 7:39 PM

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

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.

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Posted by SD60MAC9500 on Friday, June 11, 2021 11:01 AM
 

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.

 

Any water to be sprayed in the Rad system more than likely had an additive to preclude scale buildup.

 
Rahhhhhhhhh!!!!
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Posted by SD60MAC9500 on Friday, June 11, 2021 11:05 AM
 

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. 

 

Your're correct the SD45's only had the water spray system. I had my units mixed up.

 
 
Rahhhhhhhhh!!!!

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