Drive line stresses

Transmission to Rear-end

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Truckedup
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Drive line stresses

Post by Truckedup » Sun Nov 29, 2015 6:19 am

In general, which component needs to transmit the most torque......The tranny input shaft, driveshaft or axle? My brain just short circuits when I think about it.
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Re: Drive line stresses

Post by Greenlight » Sun Nov 29, 2015 3:41 pm

The input shaft on the transmission has the same torque imparted on it as the engine torque.
The transmission output shaft has the engine torque multiplied by the gear ratio of the transmission (i.e. engine TQ times 1st gear ratio).
The same for the drive shaft and rear axle pinion.
The axles have the engine torque times the transmission ratio times the ring and pinion ratio (i.e. 300 lb. ft (engine) times 2.5 (1st gear ratio) time 4.11 (rear axle ratio)). Each axle takes 1/2 the load.

Of course there are some losses due to friction that occur all the way down the line.

In relation to size (OD) of these: the input shaft is the smallest, followed by the transmission output shaft, followed by the axle shafts.
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Brian P
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Re: Drive line stresses

Post by Brian P » Sun Nov 29, 2015 4:21 pm

The halfshafts also get the most abuse due to dumping the clutch with a manual, slamming an automatic into "D" at high revs ... or if the driver keeps the accelerator floored while driving over an ice patch and then reaches the end of the ice patch.

The latter technique constitutes rental-car abuse. Did it with a Chrysler K-klunker back in the day. Speedo went to 140 km/h (as high as it went), then overshot on the down side (real road speed was about 50 km/h) and went all the way back to zero, sat there for a moment, then oscillated a couple of times! Obviously the actual wheel speed wasn't doing that, but there was enough elasticity in whatever was driving the speedo to make it do that. It was funny, which of course meant it had to be repeated. Transmission still worked when I gave the car back.

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Re: Drive line stresses

Post by Truckedup » Mon Nov 30, 2015 6:41 am

So....For example ,if the clutch is mounted on the engine and then a shaft to the transmission, then a shaft to the rear differential. The second shaft in this example needs to handle more power...
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Re: Drive line stresses

Post by Greenlight » Mon Nov 30, 2015 2:16 pm

The only time the torque changes, is if there is a ratio change (ie. transmission ratio or rear axle ratio).
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Re: Drive line stresses

Post by MadBill » Wed Dec 09, 2015 9:36 pm

Truckedup wrote:So....For example ,if the clutch is mounted on the engine and then a shaft to the transmission, then a shaft to the rear differential. The second shaft in this example needs to handle more power...
More torque but the same power.
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