For those of you that are "challenged" backing up

RedRocket204 wrote:

Wes Tausend wrote:

fj12ryder wrote:

Wes Tausend wrote:
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If any of you guys want to race backwards, I once backed up at over 40 mph with more than one trailer (across a bridge mind you). And all I needed was my mirrors and a little help to watch for traffic. :)

Wes
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Riiiiiight. lol

Howard,

Well I admit it involved rails. :)

Wes
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LOL and :C


How much torque do one of those have?

Red,

I'm not sure about the torque, or if there is even a rating. Stuff starts to break or slip before it maxes out.

On the newer units, I've seen a single locomotive develop about 134,000 pounds of traction (at about 900-1000 rpm), and each locomotive usually weighs about 415,000 pounds. I don't think the engines will get any heavier since there is a limit how much contact pressure can be put on the rails with the wheel sizes used. The contact patch is not much larger than the size of a dime, and only that because there is already a slight amount of compression flattening on each of the twelve normally round steel wheels.

Since a single car can weigh up to 280,000 pounds (depending on bridge limits), locomotive traction becomes the major limiting pulling factor rather than torque. Ever since the advent of diesel-electric locomotives (1950's), automatic traction control has been incorporated. If it fails, the errant axle will quietly burn right through the rails in seconds, causing a long delay. Such slippage is not so noticeable to the operator as was the old steam powered units, of which each had it's own operator and made a racket when it slipped. Still, like a drag racer, the steam locomotive operators needed a deft touch.

Traction can only be added by using more locomotives, usually on the head end. In this case, the operator must be mindful of total tractive effort. Each HD coupler knuckle (type F) is limited to 395,000 pounds and protects the rest of the draw bar from damage. They are fairly quick to change, requiring only removing a cotter key to lift a large kingpin out and swap castings. It still takes at least an hour by the time safe arrangements and a new 80# knuckle is on site. Note since the knuckle is only rated for 395k and each locomotive can easily develop 134k, that if three head-end locomotives are loaded in consist, the total added tractive effort rises above 400k and exceeds knuckle separation design. If a train breaks, the trainman (conductor) will not be pleased with his engineer, nor will management. Adding Distributed Power (pusher locomotives at the rear for instance) has eased the danger.

Finally, I think the diesel-generator torque capacity has exceeded the six traction motors combined capacity for some time. We no longer observe draw force by amperage since the computer reads out directly in pounds of tractive effort, but I will guess that each motor draws as much as 1500 amps, and amps are directly related to the magnetic torque the motors develop. With a few size measurements, and some calculations, one might estimate the max torque of each motor. In reality this info no doubt exists somewhere, but I've never seen it. A really bright, well trained Roundhouse employee might see, and remember it from a class somewhere. He would have to love machines like I do.

Wes
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