There are times when there will be 20+ locomotives at the head of a train when it clearly couldn't use all of them. I think this is generally to move them to a different location(?).
Do any more than what's required to pull the consist (term used for entire train or only to the locomotives?) have their engines (prime movers?) running at idle for any reason?
If the locomotive doesn't have its engine running, can it still assist with dynamic braking?
Is there any way to disengage the gearing for the electric motor from the axle to reduce wear and the (minimal) load it adds to pulling the locomotive?
Perry BabinThere are times when there will be 20+ locomotives at the head of a train when it clearly couldn't use all of them. I think this is generally to move them to a different location(?).
Even the French two-speed trucks were not 'field-switchable' between ratios -- to change from passenger to freight gearing you had to go into the shop.
I don't have numbers on the actual resistance from crater- (or whatever-) lubricated gears on a current 6-motor road locomotive, but even when cold it is probably something you could overcome with a pinch bar.
When I was working (up to December 2016) on CSX the maximimun number of locmotives in a engine consist was 12.
The maximum number of locomotives that were allowed to be on line for pulling power was limited to the number of powered axles allowed. That number having been calculated in concert with the maximum strength of couplings on the maximum grades on the property. Too many units on line do have the power to really pull the train in two, just from their tractive effort.
Locomotives are moved for many reasons - taking recently shopped engines to outlying locations for use as well as bringing defective or 92 day 'form' engines to shops for their required 92 day general inspection.
For the most part, you will never see more than three engines on the head end of a CSX train supplying power to move the train, while there may be more engines in the locomotive consist. Engines not being used for power can be moved with their diesels running or shut down. In cold weather, if the diesel engine is shut down, the cooling system in most cases will be DRAINED so that it does not freeze. The exception to this would be if the locomotive is equipped with a small auto start engine with sensors that will circulate its cooling water through both its cooling system as well as main diesel engine's cooling system.
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The western roads seem to have a penchant for major moves of motive power. Sometimes they don't even bother with a train - it's just a bunch of locomotives. Virtual Railfan's "Grab Bag" videos often include such moves.
As often as they seem to appear, I suspect that some of the moves are simply repositioning/balancing moves.
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tree68The western roads seem to have a penchant for major moves of motive power. Sometimes they don't even bother with a train - it's just a bunch of locomotives. Virtual Railfan's "Grab Bag" videos often include such moves. As often as they seem to appear, I suspect that some of the moves are simply repositioning/balancing moves.
Every carrier and virtually every division within the carrier have their own policies concerning how light power will be moved around the railroad.
I worked on one CSX division where the Division Manager WOULD NOT permit any light power moves to be operated on the Division. There were more than one knock down drag out between the Division Manager and the Power Bureau about the need to have the engines moved between locations. The DM's contention was that there were more than enough Scheduled trains for the power to be moved where it was needed. The PB contention was that the power was needed in a time frame that Scheduled trains would not fulfill. And around they would go!
The DM and PB both report to different organizational chains, even though both chains ultimately meet at the top.
Some territories have nominally balanced power requriement. Some territories have a situation where more power is routinely used in one direction and not the other - a situation that CAN be changed with differing customer requirments.
Example - Coal trains into Baltimore (at the time of lose car coal shipments) required 3 units. Empty trains out of Baltimore back to the mines only required 2 units. Periodically a Ore boat would dock and unload into railcars - where normal coal and empty trains were 150 cars; loaded ore trains would tonnage out with 75 cars and require 4 units. Thus the 150 inbound coal cars that came in with 3 units would require 8 units to move those 150 cars outbound as ore trains.
Some times they do an engine move to pick up a train on line, such as a grain train out of an elevator. Sometimes they move one or more to a train that lost an engine or two on line.
A while back I was called for a single engine light power move. We were going to a station that had an ethanol plant, and were to pick up an engine there. I figured we would turn into an originating ethanol train.
Instead, another train lost an engine. We were instructed to give that train our single engine and ride the coal train behind us into our terminal. This was on double track, so it's not like we had to stand out in the cold (and it was that night) and wait for the coal train.
Jeff
Overmod Not on any modern North American road locomotive. The pinion on the motor is in constant mesh with the bull gear on the axle, in a sealed bath of heavy lubricant, and neither an 'idler' disengaging mechanism (as on a booster or auxiliary locomotive) nor any sort of clutch capable of efficient operation at that horsepower in that environment has even been made to work and hold up cost-effectively. Even the French two-speed trucks were not 'field-switchable' between ratios -- to change from passenger to freight gearing you had to go into the shop. I don't have numbers on the actual resistance from crater- (or whatever-) lubricated gears on a current 6-motor road locomotive, but even when cold it is probably something you could overcome with a pinch bar.
Not on any modern North American road locomotive. The pinion on the motor is in constant mesh with the bull gear on the axle, in a sealed bath of heavy lubricant, and neither an 'idler' disengaging mechanism (as on a booster or auxiliary locomotive) nor any sort of clutch capable of efficient operation at that horsepower in that environment has even been made to work and hold up cost-effectively.
The AC traction gearing from both builders use oil (not sure what weight) as the gearcase lubricant. On EMD locos, the oil also lubricates the pinion end traction motor bearing via the oil carried up by the gears; I think GE does the same. A good friend and the engineer who designed the EMD AC traction system gearing in conjunction with Siemens retired and went to GE to develop their system. AC gearcases are heavy steel with a bolted split line to hold the oil in. Late model EMD DC locos also use oil-filled gearcases - crater is still used on the older stuff.
Dave
The only light power I ever see in my neck of the woods is when Amtrak has to pull power from the Autotrain and move them up to Ivy City for maintenance beyond the light work they do at Lorton.
I've seen Crater mentioned a few times. I've never seen it (in person) but from photos, it appears to be something very close to a liquid form of tar. Is that about what it is, or is it more refined?
I believe Crater was a trademark of Texaco. It is made in several 'heat ranges' and was originally designed as a lubricant for open gears, wire rope, 5th wheels and the like. In part it was chosen for gearcases because it would not spin off teeth and cake against the case in cold weather, in part because it would have very minimal leakage through shaft seals, joints, or cracks/damage.
It was said to have an asphaltic/bituminous base, with refined oil components from 15 to 50 carbons, but this makes up only 30 to 69% (depending on the temperature range) with all sorts of proprietary ingredients cagily referred to in the SDS only by their CAS numbers. These include: rust and corrosion inhibitors, extreme-pressure additives, antiwear additive, friction modifiers, adhesive and cohesive agents, and molybdenum disulfide.
The viscosity translates to between SAE 360 to 430 (which is as terribly sticky as you'd expect). The traditional way it came to be used was in one-pound sealed polyethylene bags -- these were dumped into the gearcase from the top and chewed up by the gear teeth, with the bag apparently causing no particular issue with seals or tribology.
There are competing products, including a version from Germany that is loaded with Teflon (PTFE or similar fluorocarbon) .
I can easily see why, with better gear machining and crowning calculation, a more fluid oil that would allow more specific filling volume and perhaps bottom drainage and Blackstone-style testing would come to be used.
OvermodI believe Crater was a trademark of Texaco. It is made in several 'heat ranges' and was originally designed as a lubricant for open gears, wire rope, 5th wheels and the like. In part it was chosen for gearcases because it would not spin off teeth and cake against the case in cold weather, in part because it would have very minimal leakage through shaft seals, joints, or cracks/damage. It was said to have an asphaltic/bituminous base, with refined oil components from 15 to 50 carbons, but this makes up only 30 to 69% (depending on the temperature range) with all sorts of proprietary ingredients cagily referred to in the SDS only by their CAS numbers. These include: rust and corrosion inhibitors, extreme-pressure additives, antiwear additive, friction modifiers, adhesive and cohesive agents, and molybdenum disulfide. The viscosity translates to between SAE 360 to 430 (which is as terribly sticky as you'd expect). The traditional way it came to be used was in one-pound sealed polyethylene bags -- these were dumped into the gearcase from the top and chewed up by the gear teeth, with the bag apparently causing no particular issue with seals or tribology. There are competing products, including a version from Germany that is loaded with Teflon (PTFE or similar fluorocarbon) . I can easily see why, with better gear machining and crowning calculation, a more fluid oil that would allow more specific filling volume and perhaps bottom drainage and Blackstone-style testing would come to be used.
All I can say from my walks in and around locomotive service locations at the yards I worked - get traction motor lubricant on your shoes and you played hell getting it off and if you didn't get it off you tracked it all over,
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