conjunction with the engagement of the wedges. The switch is normally held closed and opens
as the associated link is pivoted by its spring. Opening the switch contacts breaks the circuits to
the hoist motor contractors. Simulate a slack or broken rope condition as follows:
a. Position a suitable hydraulic floor jack directly under a structural part of the platform.
b. Lower the platform onto the jack.
c. With the jack, raise the platform until a slack cable condition is achieved.
d. Release the jack so it no longer supports the platform.
e. The broken rope safety device shall prevent the platform from falling.
f. To reset the broken rope safety, depress and hold the crane safeties bypass switch and place
the joystick master in the hoist direction.
g. Check the hoist drum to insure that the cable has not jumped any grooves.
16.4 INSPECTION OF THE AISLE DRIVE
The aisle drive system consists of a motor, gear case, motor brake, load brake, drive wheel and
idler wheel. (See Figures 16-10 and 16-11). Motor torque is transmitted through the reducer gear
case to the flangeless drive wheel, which drives the entire stacker along the single rail mounted
on the floor. Speed control is achieved by varying the excitation current to the drive motor field
and the magnetorque load brake. The holding brake, which is a disc type brake, serves to bring
the crane to a complete stop and to hold the crane in position. This brake is spring-set and
Check the motor bearings for proper lubrication and vibration due to wear. Check the motor
brushes for adjustment or replacement and the slip ring for reconditioning and cleanliness.