Ashley P

Springfield TN

15 posts in this topic

Love a good tractor pull! Guy I work with has a pretty successful 2WD truck. Love going to watch him put on a show. Truck's name is "Tremor" if anyone cares to google it.

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Disney, do you know much about his drivetrain?  I'm curious as to trans and rear diff stuff.  The "axle hop" that those rigs tolerate has to be the worst possible.

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It's very basic, but very robust stuff. Just a fwd and rev gear. Huge rear diff. The amazing part is the driveshaft. It's way way way smaller than i'd thought.

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Do you know what make the diff is?  They used to use Rockwells a lot, and those would allow a small driveshaft as they're double reduction.

Robust!!  Is that the first word they teach in engineering school?  lol  (EVERY GM TSB about a stronger upgrade would have to say robust about 3 times.  lol)

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He said his is an Eaton diff with a P75 planetary on it. Said pretty much all trucks/tractors use the Rockwell, or an aftermarket version of it and his Eaton is basically the same.

He has no trans. Comes out of the clutch to a reverser then to the planetary mounted to the diff.

He said part of why the small driveshaft living is they only make them up to 32" in length. Says any more than that and they can start whipping. Makes sense, but I still don't see how it holds that much power.

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Thanks.

Hey, you're an engineer.  You know that the shaft isn't gonna fail due to power, but to force.  Torque.  With no trans, torque is nil.

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20 hours ago, Ashley P said:

Thanks.

Hey, you're an engineer.  You know that the shaft isn't gonna fail due to power, but to force.  Torque.  With no trans, torque is nil.

Power is the rate at which work is done. Work is done by force. So to say something has a lot of power means it can do a lot of work over a period of time. So yes, the shaft would fail due to power. 

The equation for power V=I x R can also be related in a physical sense for power: P=W/t or W=P x t

I think the torque is not nil.....

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27 minutes ago, Disney said:

Power is the rate at which work is done.

Work is done by force.

Yes.

No. Work is done by force AND motion.  A horse lifting 33,000 lbs upward 1 foot in 1 minute is one HP.   A horse straining against an UNmoving 33,000 lbs is doing no work.

 

Sure that engine is making a lot of torque, but if all torque multiplication occurs after the driveshaft, that shaft has about 1/6 as much torque as a drag car with the same engine.  (Drag car 2:1 torque converter x 3:1 first gear = engine torque x 6.)

Speeding up shafts allows them to transmit the same power without breaking.  And  power has never twisted a shaft in two.

 

 

 

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Thank you for schooling me on power and torque. I could have saved a lot of money on my education by just arguing with you instead.

 

Oh, I didn't realize you were talking about your average 3000hp drag car torque. I thought you were talking about your 1998 Toyota Corrola torque.

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23 hours ago, Disney said:

Thank you for schooling me on power and torque. I could have saved a lot of money on my education by just arguing with you instead.

I don't know whether to send you a bill for my services, certificate of accomplishment, or both.

 

I am sincerely interested in pulling trucks/tractors specifically because of the tremendous loading on the driveline.   When axles of about 4" in diameter twist off....there's some serious forces involved.  Even dirt drag cars break axles more often than similar cars on asphalt.  Speculation is that it's because of violent loading/unloading of the axle during the run.

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