The test shown below is normally used for servo motors but can be handy in situations where no manufacturer's data is available or the motor condition is unknown.

Torque is tested with a horizontal spring scale as shown in the drawing, with the smallest and lightest motor pulley available to minimize inertia.

Hanging weights from the cord to measure torque will not work properly due to the inertial effect of the weights.

Torque in ounce-inches is equal to the pulley radius divided by the force measured by the scale. Multiply by .7061541 to convert to Newton-centimeters. (Ncm)