Reference
Only
Manitowoc
Published 05-16-17, Control # 233-03
1-47
999 SERVICE/MAINTENANCE MANUAL
INTRODUCTION
1
Gantry Cylinders Lower
See Figures
Place boom hoist brake switch (9) in off - park position. Boom
hoist brake HS-13 remains spring-applied to boom hoist
drum until the PC releases the brake. Boom hoist drum pawl
out solenoid HS-15 is enabled to disengage pawl from boom
hoist drum. Boom control handle circuit to the PC remains
open.
To lower gantry in Crane Setup mode when rigging is
installed, move boom hoist handle (1) all the way back.
Handle neutral switch closes, sending an input voltage of 5
volts or more to PC. The PC sends a positive output signal to
brake release solenoid HS-13. Brake release solenoid valve
shifts, to block tank port and open port from low-pressure
side of closed-loop to boom hoist brake cylinder spring,
releasing brake. The PC sends a negative output signal to
enable boom hoist pump EDC that tilts pump swashplate to
stroke boom hoist pump in the raise direction.
The PC sends a negative output voltage to rear drum pump
EDC (13) that tilts rear drum pump swashplate to stroke
pump in the low-pressure side direction.
Low-pressure side hydraulic fluid flows to gantry retract
cylinder solenoid HS-4 of accessory valve and through free
flow check valve sections on side “B” of load equalizing valve
(8).
From equalizing valve, fluid enters counterbalance valves (7)
and rod end of gantry cylinders (6), retracting cylinder rod to
lower the gantry. As gantry raises, boom hoist drum hauls in
wire rope. The PC monitors rear drum pressure senders to
control gantry cylinder lowering speed rate.
Summary of Contents for 999
Page 1: ...R e f e r e n c e O n l y Service Maintenance Manual Manitowoc 999 ...
Page 2: ...R e f e r e n c e O n l y ...
Page 4: ...R e f e r e n c e O n l y THE ORIGINAL LANGUAGE OF THIS PUBLICATION IS ENGLISH ...
Page 297: ...R e f e r e n c e O n l y ...
Page 298: ...R e f e r e n c e O n l y ...