A friend and I were discussing locomotive designs the other night and we wondered what a tunnel motor radiator section would look like on an SD60. Well, here is an example wearing SP paint.
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Dont you just love when I get random thoughts that inspire you? This looks amazing, man!
Your friendly neighborhood CNW fan.
I would like to have an expert understanding of just how the tunnel motor works. Is the air intake for the prime mover also lower to the ground for cooler air? From what I gather it is not. Just how hot is it in the top of a tunnel? How does the crew survive the trip? How long does it take for the prime mover with 300 gal or more of coolant to over heat?
I have seen many pictures of trains going thru tunnels and not most are tunnel motors. How do they not over heat?
aut1rml I would like to have an expert understanding of just how the tunnel motor works. Is the air intake for the prime mover also lower to the ground for cooler air? From what I gather it is not. Just how hot is it in the top of a tunnel? How does the crew survive the trip? How long does it take for the prime mover with 300 gal or more of coolant to over heat? I have seen many pictures of trains going thru tunnels and not most are tunnel motors. How do they not over heat?
There are a number of things working to keep the "tunnel motor" cool.
The problem for normal EMD radiators is that they are at the top of the hood and pick up air heated by the engine exhaust (or downhill, the dynamic brakes). The tunnel motor design picks up the air from frame level which should be much closer to ambient temperature. The other change is fitting the fans below the radiator cores so that they blow the air through rather than sucking it through. This makes the radiator more effective, since the air velocity is higher.
The air intake is in the usual place, at the top of the hood just behind the dynamic brakes in the illustration provided. The air is going to be heated in the turbocharger anyway, then cooled by the intercooler to increase the density.
The SP wanted these locomotives for the Donner Pass line where as well as tunnels there are miles of snow sheds to keep the track free from snow drifts. These are, of course on quite long grades where the the locomotives will be working hard in sets of four or more and the trailing units will have a hard time. Of course, it was on these lines that SP needed the Cab Forwards in steam days to keep the crew away from steam exhaust. They could be working in notch 8 for more than an hour with these conditions towards the summit which wouldn't help.
In Australia there were problems with locomotives drawing hot air in single track tunnels. These had SD 40-2 power equipment with SD50 electrical equipment in a cowl body. The combination meant they could be loaded right down to minimum speed because of the super series wheel slip control. Like an F40PH, the air intake was on the angle of the roofline, as was the radiator intakes.
The electronic controls were sensitive to the high temperature of the air drawn in by the second unit in tunnels, and the second unit would shut down. The air intake was moved from the roof angle to the flat side just below, and that apparently solved the problem.
M636C
It would have been an interesting beast. Oddly, with the length and lines of the SD60, a tunnel motor end wouldn't really stand out as it did on older models.
Thank you for the information.
Is the problem coolant overheating or rather the air charge cooler becoming less effective with the air intake near roof level. I can see both beeing a problem. Is the aircharge cooler mounted with the radiators or does it have it's own fan.
I have read of turbo problems with the GEVO and wonder how much boost do they and the EMD 710 make?
aut1rml Is the aircharge cooler mounted with the radiators or does it have it's own fan.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
M636Caut1rml I would like to have an expert understanding of just how the tunnel motor works. Is the air intake for the prime mover also lower to the ground for cooler air? From what I gather it is not. Just how hot is it in the top of a tunnel? How does the crew survive the trip? How long does it take for the prime mover with 300 gal or more of coolant to over heat? I have seen many pictures of trains going thru tunnels and not most are tunnel motors. How do they not over heat? There are a number of things working to keep the "tunnel motor" cool. The problem for normal EMD radiators is that they are at the top of the hood and pick up air heated by the engine exhaust (or downhill, the dynamic brakes). The tunnel motor design picks up the air from frame level which should be much closer to ambient temperature. The other change is fitting the fans below the radiator cores so that they blow the air through rather than sucking it through. This makes the radiator more effective, since the air velocity is higher. The air intake is in the usual place, at the top of the hood just behind the dynamic brakes in the illustration provided. The air is going to be heated in the turbocharger anyway, then cooled by the intercooler to increase the density. The SP wanted these locomotives for the Donner Pass line where as well as tunnels there are miles of snow sheds to keep the track free from snow drifts. These are, of course on quite long grades where the the locomotives will be working hard in sets of four or more and the trailing units will have a hard time. Of course, it was on these lines that SP needed the Cab Forwards in steam days to keep the crew away from steam exhaust. They could be working in notch 8 for more than an hour with these conditions towards the summit which wouldn't help. In Australia there were problems with locomotives drawing hot air in single track tunnels. These had SD 40-2 power equipment with SD50 electrical equipment in a cowl body. The combination meant they could be loaded right down to minimum speed because of the super series wheel slip control. Like an F40PH, the air intake was on the angle of the roofline, as was the radiator intakes. The electronic controls were sensitive to the high temperature of the air drawn in by the second unit in tunnels, and the second unit would shut down. The air intake was moved from the roof angle to the flat side just below, and that apparently solved the problem. M636C
With all due respect, this is not quite right. I know, because I got schooled on it by none other then Mark hemphill. The air may be cooler lower in the tunnel for a trailing unit or two but the turbulance stirs the air and evens it out somewhat. And the radiators are more efficient with the fans blowing instead of sucking. But the real deal is the SD40-2 cooling system was under designed, a weakness most railroads probably didn't even notice. but with all the tunnels and sheds in steep territory on a railroad that liked to drag everything but the kitchen sink...... So the tunnel motor was built with a much better cooling capacity.
It's all about recovery between the tunnels.
With all due respect, this isn't quite right. I used to think it was till Mark hemphill schooled me. the location of the intakes is not to draw cool air from lower in the tunnel, turbulance stirs the air anyway. The thing is the SD40-2 had a underdesigned cooling system. The tunnel motors have a much better cooling capacity.
It' all about the recovery BETWEEN the tunnels.
aut1rml Is the problem coolant overheating or rather the air charge cooler becoming less effective with the air intake near roof level.
Is the problem coolant overheating or rather the air charge cooler becoming less effective with the air intake near roof level.
The problem with the SD-40s and SD-45s in the tunnels and showsheds of the Sierras was overheated coolant.
The coolant temperatures rose to the point where they hit the high temp alarm thus shutting the prime mover down. The "Tunnel Motor" design moved the radiator air inlet from near the roof which was very hot to the comparatively cool air at frame level.
Mike
chad thomas M636C aut1rml I would like to have an expert understanding of just how the tunnel motor works. Is the air intake for the prime mover also lower to the ground for cooler air? From what I gather it is not. Just how hot is it in the top of a tunnel? How does the crew survive the trip? How long does it take for the prime mover with 300 gal or more of coolant to over heat? I have seen many pictures of trains going thru tunnels and not most are tunnel motors. How do they not over heat? There are a number of things working to keep the "tunnel motor" cool. The problem for normal EMD radiators is that they are at the top of the hood and pick up air heated by the engine exhaust (or downhill, the dynamic brakes). The tunnel motor design picks up the air from frame level which should be much closer to ambient temperature. The other change is fitting the fans below the radiator cores so that they blow the air through rather than sucking it through. This makes the radiator more effective, since the air velocity is higher. The air intake is in the usual place, at the top of the hood just behind the dynamic brakes in the illustration provided. The air is going to be heated in the turbocharger anyway, then cooled by the intercooler to increase the density. The SP wanted these locomotives for the Donner Pass line where as well as tunnels there are miles of snow sheds to keep the track free from snow drifts. These are, of course on quite long grades where the the locomotives will be working hard in sets of four or more and the trailing units will have a hard time. Of course, it was on these lines that SP needed the Cab Forwards in steam days to keep the crew away from steam exhaust. They could be working in notch 8 for more than an hour with these conditions towards the summit which wouldn't help. In Australia there were problems with locomotives drawing hot air in single track tunnels. These had SD 40-2 power equipment with SD50 electrical equipment in a cowl body. The combination meant they could be loaded right down to minimum speed because of the super series wheel slip control. Like an F40PH, the air intake was on the angle of the roofline, as was the radiator intakes. The electronic controls were sensitive to the high temperature of the air drawn in by the second unit in tunnels, and the second unit would shut down. The air intake was moved from the roof angle to the flat side just below, and that apparently solved the problem. M636C With all due respect, this isn't quite right. I used to think it was till Mark hemphill schooled me. the location of the intakes is not to draw cool air from lower in the tunnel, turbulance stirs the air anyway. The thing is the SD40-2 had a underdesigned cooling system. The tunnel motors have a much better cooling capacity. It' all about the recovery BETWEEN the tunnels.
M636C aut1rml I would like to have an expert understanding of just how the tunnel motor works. Is the air intake for the prime mover also lower to the ground for cooler air? From what I gather it is not. Just how hot is it in the top of a tunnel? How does the crew survive the trip? How long does it take for the prime mover with 300 gal or more of coolant to over heat? I have seen many pictures of trains going thru tunnels and not most are tunnel motors. How do they not over heat? There are a number of things working to keep the "tunnel motor" cool. The problem for normal EMD radiators is that they are at the top of the hood and pick up air heated by the engine exhaust (or downhill, the dynamic brakes). The tunnel motor design picks up the air from frame level which should be much closer to ambient temperature. The other change is fitting the fans below the radiator cores so that they blow the air through rather than sucking it through. This makes the radiator more effective, since the air velocity is higher. The air intake is in the usual place, at the top of the hood just behind the dynamic brakes in the illustration provided. The air is going to be heated in the turbocharger anyway, then cooled by the intercooler to increase the density. The SP wanted these locomotives for the Donner Pass line where as well as tunnels there are miles of snow sheds to keep the track free from snow drifts. These are, of course on quite long grades where the the locomotives will be working hard in sets of four or more and the trailing units will have a hard time. Of course, it was on these lines that SP needed the Cab Forwards in steam days to keep the crew away from steam exhaust. They could be working in notch 8 for more than an hour with these conditions towards the summit which wouldn't help. In Australia there were problems with locomotives drawing hot air in single track tunnels. These had SD 40-2 power equipment with SD50 electrical equipment in a cowl body. The combination meant they could be loaded right down to minimum speed because of the super series wheel slip control. Like an F40PH, the air intake was on the angle of the roofline, as was the radiator intakes. The electronic controls were sensitive to the high temperature of the air drawn in by the second unit in tunnels, and the second unit would shut down. The air intake was moved from the roof angle to the flat side just below, and that apparently solved the problem. M636C
Actually the cooling systems of all EMD North American locomotives are designed to the same criteria, which is based on full horsepower and a particular ambient temperature, air density and water temperature out of the engine. So it is untrue that the SD40-2 is "underdesigned" and the tunnel models have more cooling capacity. The air in a tunnel is at a lower temperature than the air higher up and that is the sole reason EMD went to the trouble to design the tunnel models. While it is true the air temperature is higher for the trailing units and there is much turbulent mixing, the temperature is always higher up high in the tunnel. So by taking the radiator air in lower, there is less derating of the consist so the train makes it through the tunnels faster, at overall lower water temperatures.
BTW, EMD did preliminary design work on a GP50T but the expected order was not placed.
Dave
It’s interesting that SP was interested in tunnel motor GP50s but not tunnel motor SD50s. SP probably wanted tunnel motor GP50s for intermodal service. Of course SP didn’t order any GP50s, though they later acquired a large fleet of GP60s in the late 80s-early-90s.
Where on earth did the rumors of the SD40-2s having a weak cooling system come from? The ONLY time I have seen a -2 with hot engine failures was in the tunnels or if a fan quit working.
Lyon_Wonder It’s interesting that SP was interested in tunnel motor GP50s but not tunnel motor SD50s. SP probably wanted tunnel motor GP50s for intermodal service. Of course SP didn’t order any GP50s, though they later acquired a large fleet of GP60s in the late 80s-early-90s.
Is that why the EMD GP40X demonstrators (which were test units for the 50 series) had the "Elephant Ear" cooling system?
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
OK Dave, Mabee underdesigned is not fair. Mabee "underdesigned for SPs needs" would have been more appropriate.
Well I looked up some old threads, includeing the one where I got schooled, and unfortunately Mark's posts are gone. Anyway, I don't want to argue but I stand by what I said, it's the better cooling system that allows the units to stay in the tunnels longer and cool themselves between tunnels faster that overcame the problems with the 40 / 45 series cooling system.
http://cs.trains.com/trccs/forums/t/36388.aspx?PageIndex=1
http://cs.trains.com/trccs/forums/p/139638/1556617.aspx#1556617
carnej1 Is that why the EMD GP40X demonstrators (which were test units for the 50 series) had the "Elephant Ear" cooling system?
The 23 GP40X prototye units DID NOT have the "elephant ear" cooling system. They had SD45-style flared radiators in deference to the increased cooling demands of the 3500 HP 16-645F engine. This was an interim development model that preceeded the production GP50 model which featured an engarged, verticle radiator grill area.
It should be noted that four units for the Southern Pacific were initially equipped with experimental "elephant ear" shrouds as a test application investigated as an alternative to the "Tunnel Motor" concept. These shrouds were considered temporary fixtures and were later removed.from the locomotives.
chad thomas OK Dave, Mabee underdesigned is not fair. Mabee "underdesigned for SPs needs" would have been more appropriate. Well I looked up some old threads, includeing the one where I got schooled, and unfortunately Mark's posts are gone. Anyway, I don't want to argue but I stand by what I said, it's the better cooling system that allows the units to stay in the tunnels longer and cool themselves between tunnels faster that overcame the problems with the 40 / 45 series cooling system. http://cs.trains.com/trccs/forums/t/36388.aspx?PageIndex=1 http://cs.trains.com/trccs/forums/p/139638/1556617.aspx#1556617
It is a better cooling system if you have a lot of tunnels. But away from tunnels, each cooling system meets the design criteria, which is the same for both. The reason the tunnel locos cool faster between tunnels is because the water did not get as hot inside the tunnel, so the cooling system is starting from a lower temperature on exit, thus it cools to a lower temperature before the next one.
So the cooling system comes into play while the train is inside the tunnel as well? As in it keeps the water temperature low so that it's faster to cool it when the train exits the tunnel?
And for that matter, how did this design become obsolete? What made the later locomotive designs able to handle the temperature?
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