INTRODUCTION 777 SERVICE MANUAL
1-54 Published 10-01-2012, Control # 045-08
Front Drum in Free Fall
See Figures 1-37 and 1-38 for following procedures.
For free fall lowering, front hoist control handle must be in the
off position. The PC then closes the circuit to front drum
clutch solenoid HS20, supplying hydraulic pressure to the
front drum clutch cylinder which disconnects the front drum
from the front hoist motor drive assembly.
NOTE: When the drum working brakes are released, the
load on the drum will free fall. Lowering speed must
be controlled with the drum working brake.
If control handle is moved in up direction from off, the PC
immediately opens the circuit to HS20, spring-applying the
clutch to connect the front drum to the motor drive assembly.
The load is then powered in the up direction. When control
handle is returned to off, the clutch is again released,
returning the drum to the free fall condition. At this time, a
FIGURE 1-38
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