J

J SECONDS (DC MOTORS)

J is the per unit moment of inertia.  It is defined as the time in seconds to accelerate the motor armature to rated base speed using rated full load torque. 

JACKSCREW

A device used for leveling the positioning of a motor.  These devices are adjustable screws that fit on the base or motor frame.  Also a device for removing endshields from a motor assembly.