Re: [MV] Need Field Expedient Pinion Nut Torque Wrench

Lee Ethridge (leeethridge@ibm.net)
Tue, 3 Feb 1998 09:04:35 -0600

I'm facing the same problem, but with axle nuts. My solution will be to
call tool rental centers until I find one that will rent an appropriate
torque wrench.

If you get really desperate, though, just think about what a foot pound
is. You should be able to make a device with a fixed weight a fixed
distance from a socket. Let's say, for example, a 50 pound bag of sand
at the end of a 6 foot pipe slipped over a 3/4" breaker bar with your
pinion nut socket attached.

Remember to keep the pipe horizontal and don't apply any force other
than the weight of the bag of sand. In particular, don't drop the bag
of sand. The force applied by a falling bag of sand far exceeds that of
a stationary bag of sand.

Also remember to consider the weight of the pipe. To be accurate, you
need to reduce the weight of the bag of sand by 1/2 the weight of the
pipe. And be sure the sandbag is attached 6 feet from the centerline of
the socket.

This mess is clumsy. It's best used as a gauge. You could tighten it a
little and test it with the bag of sand and pipe, and repeat the process
just until the bag of sand on the pipe failed to turn the nut.

You could also push on a pipe with a bathroom scale. Or use your body
weight, and calculate the necessary length of pipe to apply your entire
body weight to the pipe. (Desired torque / body weight = pipe length.
i.e. If you way 150 lbs, you'd need a two foot pipe to apply 300 ft-lbs
of torque.) But this is tricky and dangerous, and would probably result
in over-torqueing due to dynamic load.

I once considered using a fish scale attached a known distance from the
centerline of a socket in order to measure a very small torque. With
scales you can set the pipe vertically so that you don't have to factor
in the weight of the pipe.

Good luck,
Lee

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