On Sun, 4 Jan 2009 01:51:53 -0800 (PST), Dar
wrote:

Now I have a 1/2 hp , 247 in. lb torque, ac gearmotor that bogs down
under
the loads I need it for , and I need a bigger motor. I found another
1/2 hp motor
that has 487 in lbs , but am not certain that the higher torque
rating alone is
enough.

If you can accept about half the speed of your current motor, it is
OK. You would achieve the same if you could double the gear ratio on
your existing motor.

So the question is : what is the relationship between hp,
torque, and actual
ability to perform high-load operations

It is a very simple and direct relationship: Power is torque
multiplied by rotational speed. Depending in which measurement units
you choose, you may have to multiply by some constant.

In other words: If you keep the power constant and gear the motor to
run half as fast, it will produce twice the torque. And vice versa.
--
RoRo