Manitowoc Published 10-01-2012, Control # 045-08 1-45
777 SERVICE MANUAL INTRODUCTION
1
PC programming requires front hoist pump to stroke before
the front drum band brake HS16 is released. This ensures
adequate pressure is present to hold the load after full
release of the brake. The regulated voltage to the front hoist
pump EDC tilts the pump swashplate to stroke the pump in
the up direction. Oil then flows from pump port A to port A of
front hoist motor. If after about 2 seconds, speed sender
detects speed and brake is not released, the PC will
command release.
Front hoist pressure sender supplies the PC with pressure
information which the PC compares to the memorized
holding pressure of the front hoist. When adequate pressure
is available, the PC energizes HS16 and shifts the band
brake valve. This initiates full release of the band brake and
front hoist motor raises the load.
The PC governs the raising speed of the load by varying the
voltage to the pump EDC in proportion to movement of the
control handle. The angle of the pump swashplate is
FIGURE 1-31
To Next Page
Loading...
Need help?
General
