QUOTE: Originally posted by WilRogJr Why do they call them "tunnel" motors?
QUOTE: Originally posted by gabe QUOTE: Originally posted by WilRogJr Why do they call them "tunnel" motors? Oh my goodness, a technical question to which I actually know the answer. Move over Randy Stall (joking). They call them tunnel motors because the locomotives were designed to operate more effectively in tunnels. Some railroads, especially the SP, had a considerable amount of long tunnels on their system. The problem with long tunnels is the exhaust from the diesles would reflect in the tunnel and cause temperatures to rise and sometime cause the engine to shut down. This is also the reason the SP developed cab first steam locomotives. Tunnel motors have the intakes closer to the ground where the air is cooler (heat rises) and the intake of cooler air allows them to operate in tunnels for longer periods without over heating. When you see an SD-40-2T look toward the back of the locomotive close to the walkway. On a related aside--the story of UP's 4-8-4 and 4-6-6-4 having a diesle haul them through a tunnel on their way to a steam convention and the diesle overheating is a classic. The two steamers had to steam up in the tunnel and it got so hot the crews nearly melted and all of the smoke alarms in the passenger cars went off. Although, I bet the tunnels got a nice steam cleaning from all of that diesel soot on them. Gabe
QUOTE: Originally posted by Randy Stahl QUOTE: Originally posted by gabe QUOTE: Originally posted by WilRogJr Why do they call them "tunnel" motors? Oh my goodness, a technical question to which I actually know the answer. Move over Randy Stall (joking). They call them tunnel motors because the locomotives were designed to operate more effectively in tunnels. Some railroads, especially the SP, had a considerable amount of long tunnels on their system. The problem with long tunnels is the exhaust from the diesles would reflect in the tunnel and cause temperatures to rise and sometime cause the engine to shut down. This is also the reason the SP developed cab first steam locomotives. Tunnel motors have the intakes closer to the ground where the air is cooler (heat rises) and the intake of cooler air allows them to operate in tunnels for longer periods without over heating. When you see an SD-40-2T look toward the back of the locomotive close to the walkway. On a related aside--the story of UP's 4-8-4 and 4-6-6-4 having a diesle haul them through a tunnel on their way to a steam convention and the diesle overheating is a classic. The two steamers had to steam up in the tunnel and it got so hot the crews nearly melted and all of the smoke alarms in the passenger cars went off. Although, I bet the tunnels got a nice steam cleaning from all of that diesel soot on them. Gabe Fine job grasshopper.
QUOTE: Originally posted by gabe QUOTE: Originally posted by Randy Stahl QUOTE: Originally posted by gabe QUOTE: Originally posted by WilRogJr Why do they call them "tunnel" motors? Oh my goodness, a technical question to which I actually know the answer. Move over Randy Stall (joking). They call them tunnel motors because the locomotives were designed to operate more effectively in tunnels. Some railroads, especially the SP, had a considerable amount of long tunnels on their system. The problem with long tunnels is the exhaust from the diesles would reflect in the tunnel and cause temperatures to rise and sometime cause the engine to shut down. This is also the reason the SP developed cab first steam locomotives. Tunnel motors have the intakes closer to the ground where the air is cooler (heat rises) and the intake of cooler air allows them to operate in tunnels for longer periods without over heating. When you see an SD-40-2T look toward the back of the locomotive close to the walkway. On a related aside--the story of UP's 4-8-4 and 4-6-6-4 having a diesle haul them through a tunnel on their way to a steam convention and the diesle overheating is a classic. The two steamers had to steam up in the tunnel and it got so hot the crews nearly melted and all of the smoke alarms in the passenger cars went off. Although, I bet the tunnels got a nice steam cleaning from all of that diesel soot on them. Gabe Fine job grasshopper. Thank you master. Now, if I can only figure out how to reduce the vibration damage caused by the 645 in an SD-50, I will be able to leave the school and go out in the world to combat the evils of middle/upper management. Gabe
USAF TSgt C-17 Aircraft Maintenance Flying Crew Chief & Flightline Avionics Craftsman
QUOTE: Originally posted by gabe Now, if I can only figure out how to reduce the vibration damage caused by the 645 in an SD-50, I will be able to leave the school and go out in the world to combat the evils of middle/upper management. Gabe
-ChrisWest Chicago, ILChristopher May Fine Art Photography"In wisdom gathered over time I have found that every experience is a form of exploration." ~Ansel Adams
QUOTE: Originally posted by Hugh Jampton I heard a rumour that the intakes were lowered because that's where the oxygen is,, the top space of the tunnel fills with exhaust, which has no (or very little) oxygen in it, I would have thought that trailing units were particularily succeptable to oxygen starvation, especially if the tunnel is on a rising gradient and the units are have to work a bit.
"No soup for you!" - Yev Kassem (from Seinfeld)
QUOTE: Originally posted by CopCarSS QUOTE: Originally posted by gabe Now, if I can only figure out how to reduce the vibration damage caused by the 645 in an SD-50, I will be able to leave the school and go out in the world to combat the evils of middle/upper management. Gabe Gabe, I'm shocked! Didn't you read the propaganda in the last Trains? Chris Snowy Denver, CO
QUOTE: Originally posted by chad thomas The tunnel motor design is all about pulling in cooler air while inside the tunnels and snowsheads. But naturally they will cool down in between tunnels. Also remember this is mostly for the trailing units. SP liked to run monster drags when it could and Donner is no exception. So you would have these monster consists of up to 8-9 units on the point. When you are grinding uphill at little more than a walking pace behind 8 other units doing the same, thing can get pretty hot in those tunnels. If the cooling system can't keep up the engines overheat and will unload to protect themselves.
QUOTE: Originally posted by TheAntiGates QUOTE: Originally posted by chad thomas The tunnel motor design is all about pulling in cooler air while inside the tunnels and snowsheads. But naturally they will cool down in between tunnels. Also remember this is mostly for the trailing units. SP liked to run monster drags when it could and Donner is no exception. So you would have these monster consists of up to 8-9 units on the point. When you are grinding uphill at little more than a walking pace behind 8 other units doing the same, thing can get pretty hot in those tunnels. If the cooling system can't keep up the engines overheat and will unload to protect themselves. Well, not to argue,...but I really do think that the issue I'm thinking of stated that the belief that tunnel motor design is an "in tunnel" benefit was a widely held misconception, because the benefit b eing designed for was actually how rapid the motors could be cooled in between tunnels. The only reason why I even remember it was because it seemed like such a surprise at the time. Little foggy on the following, but I seem to remember the source as being EMD's *** Dillworth, and MAYBE the issue was the one that had the "Greatest/ worst" loco's of all time featured as a special article.
QUOTE: Originally posted by chad thomas Thanks for the explaination Mark. I was wrong guys. Sorry.
QUOTE: Originally posted by TheAntiGates [ I could SWEAR I read an explanation in trains magazine about 3 years ago that said the design had very little to do with "in tunnel" breathing, and more to do with the ability of the radiator to cool down quickly "between" tunnels (ie, after exiting the last one, and before entering the next one)
QUOTE: Originally posted by SSW9389 Right you are. The author was Jack Wheelihan, an EMD field rep. Look in CTC Board a couple of years ago. [8D]
QUOTE: Originally posted by Mark_W._Hemphill It does this by putting the fans on the cool side of the radiators (beneath them in this case) instead of on the hot side (above them), which makes transfer of heat between radiator and atmosphere occur at a faster rate than otherwise. You could have accomplished pretty much the same thing by reversing the fans on a standard SD40/45, but then you'd be blasting hot air out the sides, which would be a significant hazard to anyone on the walkway and possibly damage things next to the track. Better to take the hot air straight up, away from people and things.
QUOTE: Originally posted by mudchicken Most of these folks on here have not experienced working in a tunnel with a diesel engine (as opposed to a gasoline engine which would be fatally stupid, co2 vs. co)...Your view out the end of the tunnel has the horizon falling to the ground as exhaust above the spring line in the tunnel slowly heads downward.
Our community is FREE to join. To participate you must either login or register for an account.