Torque loss in Drill


I am having some trouble with torque loss from a drill motor and gearbox I harvested for a project. I followed the steps in this instructable ( to get the motor and gearbox. I then hooked it up to a motorshield and an arduino.

Originally the drill (Rigid 18v Cordless) States that it can deliver close to 500 lb-in of torque. However when I hook it up to my apparatus I am able to stop the spinning with my hand. 

I use PWM to control the speed but upping the speed still does not produce the required torque.

If anyone has any ideas as to why it dropped in torque I would be very appreciative.

Thank you in advanced.

Yonatan244 months ago

Mybe an issues with the brushes?

Toga_Dan4 months ago

the drill had plenty o torque before hacking it?

panic mode4 months ago

torque is proportional to motor current.

current is limited by resistances in the circuit. everything has resistance, motor itself, wires, PWM speed control and your power source. this is why you cannot get 9V battery to produce 100A even when shorted.

to test if your power source is the limiting factor, connect motor directly to it - without PWM. if you still get poor results, you found the problem...