Manitowoc Published 11-06-15, Control # 040-13 1-39
2250 SERVICE/MAINTENANCE MANUAL INTRODUCTION
which clutches are released, depending on control handle
command and mode selected.
Drum Pawls
A selected drum pawl must be disengaged before the drum
can operate. Components for the engage/disengage
operation for a selected drum pawl are specific to the drum
pawl system being operated. A ratchet and pawl latch
provides a positive way of locking boom hoist, luffing hoist,
front drum, rear drum, and auxiliary drum (if equipped).
With current production pawl operation is controlled with
selected drum brake switch. With past production pawl
operation is controlled with selected pawl switch.
If a pawl is engaged during hoisting up, a hoist operating
drive fault occurs when stopped because the PC cannot
command down against pawl to prove the brake is applied.
If a pawl switch is engaged accidentally when hoisting down,
the PC sends an output signal to enable that drum brake. For
the boom hoist pawl and luffing jib drum pawl, the spring
applied brake on motor end of drum shaft enables and the
pump de-strokes to stop the function. The PC delays the
engage signal to pawl engage air solenoid so the pawl does
not engage for approximately 10 seconds after hoist stops.
Load drum pawls respond similarly, but front and rear load
drum brakes are spring applied and air released.
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