I concur that Dave Goding is the likeliest way to a 'definitive' answer from EMD one way or the other.
Hesitant to mention this, but I thought the subject locomotives used an atmospheric-pressure system where the radiators drained completely back into the tank when the engine stopped pumping -- do you not read 'full' on the gauge glass only then? I thought the necessary 'siphon breakers' were the valves accessible through those ports; other vent or radiator arrangements might not have them there.
richhotrain This has been a most interesting thread, but it poses a question to which there has been no definitive answer. I think that it would be worthwhile to repost this thread on the Trains Forum. There is a lot of expertise there, and one of the regulars may have the answer that we are looking for. From time to time, I have searched Google Images and come up with nothing. I find very few photos of the round cover plates, and I find no photos of marker lights. Randy, with all due respect, your reply does not provide a possible answer. Your personal opinion is that they are vent covers, but you offer no evidence or proof to support your opinion. The link that Ed provided shows some apparent visual support for vents. Those round covers are open, as if someone is doing maintenance through access ports. https://donstrack.smugmug.com/UtahRails/Locomotive-Details/SD40-2s/i-d4vJCKC/A There has to be an answer out there somewhere. I would start with the Trains Forum. Rich
This has been a most interesting thread, but it poses a question to which there has been no definitive answer. I think that it would be worthwhile to repost this thread on the Trains Forum. There is a lot of expertise there, and one of the regulars may have the answer that we are looking for.
From time to time, I have searched Google Images and come up with nothing. I find very few photos of the round cover plates, and I find no photos of marker lights.
Randy, with all due respect, your reply does not provide a possible answer. Your personal opinion is that they are vent covers, but you offer no evidence or proof to support your opinion.
The link that Ed provided shows some apparent visual support for vents. Those round covers are open, as if someone is doing maintenance through access ports.
https://donstrack.smugmug.com/UtahRails/Locomotive-Details/SD40-2s/i-d4vJCKC/A
There has to be an answer out there somewhere. I would start with the Trains Forum.
Rich
With all due respect, In my 35 years working on locomotives I've never removed these as there was no need to.
Randy Stahl In my 35 years working on locomotives I've never removed these as there was no need to.
In my 35 years working on locomotives I've never removed these as there was no need to.
Alton Junction
Rich, Randy Stahl has a long history over on the Trains Magazine forum. He is one of the most qualified to comment here on this issue, if practical maintenance on SD40-2s is in question.
Something of interest, here, is that MM&A (one road Randy has long experience on) had four ex-MP (via CN) SD40s. One of these (5364) has both the high-mounted and low-mounted 'circles' -- so Randy would clearly have been exposed to them.
http://www.rrpicturearchives.net/showPicture.aspx?id=2736410
More interestingly, though, is locomotive 5374, which has high-mounted 'circles' but no low-mounted ones:
http://www.rrpicturearchives.net/showPicture.aspx?id=1287709
This promptly points us in the direction of seeing if CN used any kind of classification light in the high position -- or what MP might have used when these engines were delivered in August 1973. They were sisters in the same order, builder numbers 73613-1 and 73613-7 respectively, with the unit that would become 5374 originally numbered MP 801 and then 3101; of potential interest is that these then became Union Pacific units (here 4101 in UP paint, which might be compared with Don Strack's example 3192, built just over a year earlier.)
It might be relevant that the order number for that UP 3173 series begins with b/n 5819-1, very different from the preceding SD40-2s in February 1972, 7554-1 to -50, and the following in April through June 1973, 72684-1 to -40. This might -- although I'd be skeptical of its importance -- indicate a different radiator construction or detail as built, or configuration using the upper holes as access just in that builder's series.
In the meantime we have Cody blithely telling us these are for class lights -- he's an editor here, so it shouldn't be trouble for him to post and tell us why he says these are class lights, and provide us the prototype photo evidence (or EMD documentation) that proves it so.
Overmod, I have no axe to grind with Randy Stahl. I wasn't even aware of his background when I first posted a comment directed to him. But, once he made me aware of his 35 year work background, it surprised me that he said that he had no idea why those cover plates were there.
The bigger surprise though is that no one on the MR forum seems to know. That's why I suggested that the question be posed on the Trains forum. My comments on the issue are not intended to offend anybody. I am just looking for an answer to the OP's question.
richhotrainI am just looking for an answer to the OP's question.
Hopefully Dave Goding and Preston Cook will either know something or look into finding someone who does.
In the meantime, Randy can tell us about how radiators were serviced on these units ... including how the 'vacuum breakers' are arranged to let the water down out of the radiators with the engine stopped. I do not think this would be through a pressure cap as on an automotive coolant-recovery system designed to be run pressurized with 'siphoning' overflow bottle...
Refer to the EMD parts book page presented above. Part 36 and 37 are behind those little round covers. As I stated I have never used them as I usually access these from the top after the fan hatch is removed. So the short answer is the covers are used to access the fittings. I got used to working SD45s and older EMDS that did not have these covers.
Many of these covers have been removed.
The tube from the radiator tops is for letting air into the radiators to facilitate emptying the radiators when the engine is shut down. The air is displaced from the expansion tank into the radiators. EMD's are a sealed pressurized system.
Currently I have un-restricted access to MP15AC's, GP9s, F7a and a CF7. I have limited access to GP35s, SD40-2, MP15DC, GP38-2 and possibly GE dash 8.
Randy Stahl Refer to the EMD parts book page presented above. Part 36 and 37 are behind those little round covers. As I stated I have never used them as I usually access these from the top after the fan hatch is removed. So the short answer is the covers are used to access the fittings. I got used to working SD45s and older EMDS that did not have these covers.
Randy StahlRefer to the EMD parts book page presented above
I've just gone through this thread, and I can't seem to find the EMD parts book page that Randy mentions.
Did I miss something? I've been following this thread all along.
Mike.
My You Tube
mbinsewiI've just gone throught this thread, and I can't seem to find the EMD parts book page
End view of the hood with the components numbered for callout.
Thanks Overmod. I guess I scrolled right past it.
"What are these circles on EMD long hoods?" -
Port holes for hostlers performing reverse moves.
(i couldnt refuse)
PMR
I think EMD put them there because they knew it would drive the railfans nuts trying to figure out what they were.
Ken Vandevoort
I am a retired EMD Test Engineer. Both answers are correct. The holes are for optional Marker lights and can also be used to access awkward to reach Radiator Vent lines locate high in the Long Hood at the rear.
to the forum. Always good to see someone with real world experience. You are under moderation. I encourage active participation and the moderation passes quickly.
Henry
COB Potomac & Northern
Shenandoah Valley
Lonloco I am a retired EMD Test Engineer. Both answers are correct. The holes are for optional Marker lights and can also be used to access awkward to reach Radiator Vent lines locate high in the Long Hood at the rear.
Were the holes purposely designed to be optional, to be used for either marker lights or as access to radiator vent lines? What if a particular railroad chose to install marker lights? Could the marker lights be temporarily pulled out to reach the radiator vent lines and then put back in place?
It seems to me that the holes were designed to be used for one specific purpose, whatever that might be, but what do I know.
I think the mystery prevails, but my money remains on Ed's explanation.
richhotrain PM Railfan What do ya think Ed? Bet ya a glazed doughnut (breakfast time here) they are light holes! Better yet, ill make you a deal... if they are maintenance holes - ill tell ya all my secrets on 3d printing. If they are light holes... you gotta tell me your scenery and picture taking secrets.... deal? Oh boy, this is gonna be fun. I just finished making my popcorn, and the butter is being melted on the stove. Let's get ready to rumble! Rich
PM Railfan What do ya think Ed? Bet ya a glazed doughnut (breakfast time here) they are light holes! Better yet, ill make you a deal... if they are maintenance holes - ill tell ya all my secrets on 3d printing. If they are light holes... you gotta tell me your scenery and picture taking secrets.... deal?
What do ya think Ed? Bet ya a glazed doughnut (breakfast time here) they are light holes! Better yet, ill make you a deal... if they are maintenance holes - ill tell ya all my secrets on 3d printing. If they are light holes... you gotta tell me your scenery and picture taking secrets.... deal?
Oh boy, this is gonna be fun. I just finished making my popcorn, and the butter is being melted on the stove. Let's get ready to rumble!
Rio Grande. The Action Road - Focus 1977-1983
Overmod Rich, Randy Stahl has a long history over on the Trains Magazine forum. He is one of the most qualified to comment here on this issue, if practical maintenance on SD40-2s is in question. Something of interest, here, is that MM&A (one road Randy has long experience on) had four ex-MP (via CN) SD40s. One of these (5364) has both the high-mounted and low-mounted 'circles' -- so Randy would clearly have been exposed to them. http://www.rrpicturearchives.net/showPicture.aspx?id=2736410 More interestingly, though, is locomotive 5374, which has high-mounted 'circles' but no low-mounted ones: http://www.rrpicturearchives.net/showPicture.aspx?id=1287709 This promptly points us in the direction of seeing if CN used any kind of classification light in the high position -- or what MP might have used when these engines were delivered in August 1973. They were sisters in the same order, builder numbers 73613-1 and 73613-7 respectively, with the unit that would become 5374 originally numbered MP 801 and then 3101; of potential interest is that these then became Union Pacific units (here 4101 in UP paint, which might be compared with Don Strack's example 3192, built just over a year earlier.)
CN did not order rear class lights or rear numberboards on road thru freight units (GP40, SD40 and larger):
https://i.pinimg.com/originals/2b/b7/6b/2bb76bd96264f4ca0bbaa74eb123bf40.jpg
The secondhand SD40's that were acquired during the mid 1990s are a bit of a crapshoot, they were all rebuilt to some extent but they all seem to be slightly different. The only thing they have in common is the front headlight was moved to the short hood from above the windshields.
The front class lights on CN's big MLW's and many early SD40's had separate white and green aspects, but no red:
http://www.railpictures.ca/?attachment_id=26065
CN did order rear class lights on roadswitchers like GP38's, these were the tricolored assembly that were also found on CP units. Note that the round holes in question are absent here:
https://www.trainspotted.com/photos/44e41ad6496f22f5306c5a313972fa61/Canadian-National-Railway-4707-diesel-locomotive-GP38-2.jpg
Greetings from Alberta
-an Articulate Malcontent
Overmod I concur that Dave Goding is the likeliest way to a 'definitive' answer from EMD one way or the other. Hesitant to mention this, but I thought the subject locomotives used an atmospheric-pressure system where the radiators drained completely back into the tank when the engine stopped pumping -- do you not read 'full' on the gauge glass only then? I thought the necessary 'siphon breakers' were the valves accessible through those ports; other vent or radiator arrangements might not have them there.
I'm late to this discussion but since my name is mentioned, I'll chime in. For reference, I'm retired from EMD Engineering, working there from 1968 to 2015 with a few breaks.
Those blank covers do serve to access the vent line fittings as noted earlier by Lonloco and others, how often they had lights in them and whether that was the original intent, I'm not sure. Contrary to what some RR mechanics think, EMD did consider maintainability in all design work.
The EMD cooling systems are designed so the radiators drain to the water tank when the engine is shut down to prevent radiators from freezing. At idle and low notches, the radiators may not be completely full - the vent lines are connected to a port on the top of the water tank to insure the radiators will fill when the pump pressure is sufficient. At full throttle, there is a small flow thru the vent tubes back to the water tank insuring the radiators are filled.
EMD cooling systems are pressurized with a similar cap to an automotive cooling system, only much bigger. IIRC, the cap is a 12 lb. pressure relief and drains to the pit between the engine and equipment rack where it drains ultimately to the retention tank integral to the fuel tank. However, the design requires that the engine out coolant not exceed 210 deg F at full load at the design ambient, 115 or 122 deg F depending on where the loco is destined to operate. The pressure cap gives a margin above the normal boiling point for radiator fouling, tunnel operation, etc. Every new model got a cooling system performance test in the Test Shed North of the Engineering Building where the doors could be shut and the cooling air recirculated to get the actual air into the radiator temp up to the design point.
Dave
bogie_engineer Overmod I concur that Dave Goding is the likeliest way to a 'definitive' answer from EMD one way or the other. Hesitant to mention this, but I thought the subject locomotives used an atmospheric-pressure system where the radiators drained completely back into the tank when the engine stopped pumping -- do you not read 'full' on the gauge glass only then? I thought the necessary 'siphon breakers' were the valves accessible through those ports; other vent or radiator arrangements might not have them there. I'm late to this discussion but since my name is mentioned, I'll chime in. For reference, I'm retired from EMD Engineering, working there from 1968 to 2015 with a few breaks. Those blank covers do serve to access the vent line fittings as noted earlier by Lonloco and others, how often they had lights in them and whether that was the original intent, I'm not sure. Contrary to what some RR mechanics think, EMD did consider maintainability in all design work. The EMD cooling systems are designed so the radiators drain to the water tank when the engine is shut down to prevent radiators from freezing. At idle and low notches, the radiators may not be completely full - the vent lines are connected to a port on the top of the water tank to insure the radiators will fill when the pump pressure is sufficient. At full throttle, there is a small flow thru the vent tubes back to the water tank insuring the radiators are filled. EMD cooling systems are pressurized with a similar cap to an automotive cooling system, only much bigger. IIRC, the cap is a 12 lb. pressure relief and drains to the pit between the engine and equipment rack where it drains ultimately to the retention tank integral to the fuel tank. However, the design requires that the engine out coolant not exceed 210 deg F at full load at the design ambient, 115 or 122 deg F depending on where the loco is destined to operate. The pressure cap gives a margin above the normal boiling point for radiator fouling, tunnel operation, etc. Every new model got a cooling system performance test in the Test Shed North of the Engineering Building where the doors could be shut and the cooling air recirculated to get the actual air into the radiator temp up to the design point. Dave
I'm even later to this discussion. I had 38 years working on EMD locomotives. From SW9/1200 through SD/GP40s/40-2s.
The upper covers were to access the vent line at the top of the radiators. Later models had an access cover under the radiator hatch so the circles weren't needed anymore. Some roads made the modification themselves.
Second geration EMDs had dry radiators when shut down, but first generation had wet radiators, there wasn't a radiotor cap, the was a pipe that had a filler nipple on it that you slid a hose onto, then turn the treated water hose valve on. You filled it until the site glass was full or it came out out of the overflow (running or shut down). On second generation had the filler nipple also, but it was inside the door where the start switch was, you had a valve to open by the radiator cap you pulled down to relieve the pressure and open the fill pipe. You filled it to the one of the 2 full marks. The lower full mark was when the engine was running and the upper one was for when the engine was shut down.
Richard Webster
Retired from the FEC Rwy.
gmpullmanI recall asking this to someone familiar with locomotive repair and was told that they were access holes to get to fittings on the vent lines to the radiators located behind them.
fire5506The upper covers were to access the vent line at the top of the radiators.
Thanks for confirming what I understood was the function of the access holes.
Regards, Ed
Doesn't the rubber gasket mount make them hard to remove and replace? It seems to me that a bolt mount like shown here would be easier to use.
http://www.rrpicturearchives.net/showPicture.aspx?id=1319920
Mark Vinski