QUOTE: Originally posted by oltmannd QUOTE: Originally posted by stpaul I've always wondered how a diesel loco can move such great tonnages without stripping the teeth off the motor shaft also just how the gear is attached to the motor?? how does it all work together has baffeled me since the mid-50's. Is there a book on this that doesn't get all big worded and thecnological but just puts it into the average persons language? new to this site I think I'm in the right area to post this question. I think your question is about the traction motor gearing, in particular the pinion gear on the motor shaft. The first step is to find out the maximum torque the motor can produce. This is what you need to design to. The pinion is fit onto the shaft with an interference fit. That is, the inner diameter of the gear is less than the outside the diamter of the shaft so that there is constant pressure between the gear and the shaft. The total area of contact between the two determines the amount of force that can be transmitted before it slips. The size and shape of the gear teeth determines how many teeth are in contact at a time and what the contact stresses will be. The gears can be case hardened or induction hardened to improve the overall strength and wear characteristics. Finally, the lubrication system needs to designed. The lubricant has to be able to minimize tooth wear which would cause severe vibration. The basic design on an EMD traction motor has actually changed little over the years, even as maximum torque has increased. The design has been tweaked to allow for higher forces, though. Most notably, the tooth design changed with the advent of the SD50s, allowing an increas in the number of gear teeth in contact at a time, although they are smaller teeth. And, the lubrication has gotten better over the years. In the early years, an asphalt based compound was used ("crater"). Specially formulated greases replaced crater compound as the years went by. These greases were compounded with extreme pressure additives and went through extensive testing on the RRs before being adopted. New locomotives these days use oil to lubricate the gearing. The gearing has been a source of trouble for years. Slipped pinions, which generally result in the armature overspeeding and coming apart, are fairly rare, but a big problem to deal with when they occur since you can't move the locomotive until you get the motor out of there. Worn gearing has been another source of trouble. Keeping grease on the teeth during sustained 60 mph running is difficult. Worn gears create vibration which causes the motor windings to short.
QUOTE: Originally posted by stpaul I've always wondered how a diesel loco can move such great tonnages without stripping the teeth off the motor shaft also just how the gear is attached to the motor?? how does it all work together has baffeled me since the mid-50's. Is there a book on this that doesn't get all big worded and thecnological but just puts it into the average persons language? new to this site I think I'm in the right area to post this question.
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If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
QUOTE: Originally posted by adrianspeeder This is a good thread. So can we have more info on the "crater compound"? Adrianspeeder
QUOTE: Originally posted by ericsp QUOTE: Originally posted by jchnhtfd As to why the teeth in the gear train don't strip (more often[:(]): mechanical engineers who design this sort of thing have very good ways of figuring out just how much force can be transmitted through gearing without breaking things, and gear trains can be designed and built to handle just about any amount of force (torque, to be gently technical) you might want -- from the gear trains in old fashioned tick-tock watches to those found in, for instance, large ships, where you may be looking at forty to fifty thousand horsepower going through a single gear set (think all the power from 10 SD70MACs through one shaft!) or even more. I am sure you know this, but for those who do not, force and torque are not interchangeable.
QUOTE: Originally posted by jchnhtfd As to why the teeth in the gear train don't strip (more often[:(]): mechanical engineers who design this sort of thing have very good ways of figuring out just how much force can be transmitted through gearing without breaking things, and gear trains can be designed and built to handle just about any amount of force (torque, to be gently technical) you might want -- from the gear trains in old fashioned tick-tock watches to those found in, for instance, large ships, where you may be looking at forty to fifty thousand horsepower going through a single gear set (think all the power from 10 SD70MACs through one shaft!) or even more.
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QUOTE: Originally posted by jchnhtfd Once a wheel really starts to slip, though -- whether it is because of trying to put too much tractive effort through an axle or because the brakes are applied too hard -- you go from static friction (high) to sliding friction (low) and the sliding will just keep going unless you reduce the tractive effort applied (wheel slip controls, brake release) or increase the sliding friction (sand).
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
QUOTE: Originally posted by adrianspeeder QUOTE: Originally posted by CSXrules4eva Well I'm going to say a little something here that was explained to me. One of the reasons why locomotives are able to haul great tonnages in a single load is because of resistance. There is virtully very little friction of the steel wheel on the steel rail. Also the contact surface of a locomotive's wheel on rail is only three inches, therefor there is almost no rolling resistance. But Sara, the less resistance the cars have to have them roll easier also hurts the locos that would like to have a high contact force to get the train moving. Hence the use of antiwheelslip controls and sand. Adrianspeeder
QUOTE: Originally posted by CSXrules4eva Well I'm going to say a little something here that was explained to me. One of the reasons why locomotives are able to haul great tonnages in a single load is because of resistance. There is virtully very little friction of the steel wheel on the steel rail. Also the contact surface of a locomotive's wheel on rail is only three inches, therefor there is almost no rolling resistance.
QUOTE: Originally posted by adrianspeeder A mechanical engineer had to properly calculate the stress loads involved, what type and strength steel could handle that load, and what it's service life would be. Lets give a round for all the engineers out there... Adrianspeeder
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