Re: [MV] M35 Tug-Of-War...

From: BRANDSTEDT@aol.com
Date: Mon Aug 12 2002 - 15:21:16 PDT


A little math for those of you interested:
The drawbar pull is determined by the engine torque and drive train gear
ratio. The torque presented to the axles on the deuce is about 30,000 ft-lb.
The last "gear" in the drive train is the wheel and you will have to divide
the wheel radius into the 30,000 to find the actual drawbar pull. For the
900x20, that will be 1.58 ft (19 inches) and for the 1100x20 tire the radius
is 1.83 ft (22 inches). For the vehicle equipped with 900x20 tires the result
is 18,000 lb and for 1100x20 it will be about 16,000 lb.

This matches the numbers reported by David for the Aberdeen Proving Ground
tests for the M34, which has the 1100x20 tires.

If the wheels start to spin because of loss of traction the pull will be
less. When both vehicles are equally powerful, then you might as well tie the
strap to a tree, like Ken suggested, the result will be the same, a lot of
bucking when the traction is lost.

The deuce does not have an interaxle differential and will buck terribly when
the traction is unequally divided between the wheels. The bucking could
easily create tension in the strap that could far exceed the drawbar pull and
could be rather unpredictable. Bad news for the pintle hook too, not to
mention the drive train. It hurts to see a truck mistreated like that and I
always try to avoid the bucking.
Try backing uphill, that usually gets things hopping and bucking especially
when empty.

Just for the fun of it.
Bjorn
MVPA19212
1968 M35 w/HIAB crane



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