I built a tumbler a while back that used a surplus Bodine gear motor
rated 1/4 HP 96 RPM 11.0 LB-IN and it worked quite well. I now need to
build another one and I'm running into some confusion looking for
another surplus gear motor.

I'm finding gear motors with lower HP ratings but higher torque ratings
at similar RPM, such as 1/6 HP 80 RPM 82.0 LB-IN, or one that is higher
RPM and higher torque, 1/12 HP 254 RPM 17.0 LB-IN.

The connection between the gear motor and the final driven shafts is via
chain and I can readily adjust that drive ratio to get the final 50 RPM
shaft speed I need.

I'm a bit confused on whether the lower HP rating matters given the
torque ratings that are higher than I seemingly need based on the
original unit. Ignoring losses in the chain drive, that 1/12 HP motor
would seemingly give me 85 LB-IN at the shafts vs. 21 LB-IN, or the 1/6
HP one 131 LB-IN.

I must be missing something here...

Thanks,

Pete C.