Manitowoc 777 Service And Maintenance Manual

Reference Only
777 SERVICE MANUAL HYDRAULIC SYSTEM
Manitowoc Published 10-01-2012, Control # 045-08 2-13
2
Load Drums, Swing, Track, and Boom Hoist
Pump
1. Lower all loads to ground.
2. Move all control handles to off and park all crane
functions.
3. Stop engine.
4. Place a suitable container under pressure senders to
catch oil leakage.
Perform steps 5-9 only at faulty pressure senders.
5. Disconnect electric plug from pressure senders.
6. Slowly loosen pressure senders only enough to allow
any remaining pressure to exhaust.
7. Remove pressure senders.
8. Install new pressure senders and connect electric cords.
Pressure senders have pipe threads. Be sure to
install thread sealant.
9. Bleed pressure senders as follows:
a. Connect bleed lines with shut-off valves to couplers
on pressure sender manifold. Open valve in bleed
lines. Use a suitable container to catch oil flow.
b. With all control handles off, start engine and allow it
to idle.
c. Observe oil flowing from bleed lines.
d. Close valve in bleed lines when clear oil flows (no
air bubbles in oil).
e. Stop engine.
f. Remove bleed lines from couplers at pressure
senders.
10. Calibrate pressure senders (see procedure in this
section).
Boom Hoist Cylinder
1. Move boom hoist control handle to off and park boom
hoist.
2. Stop engine.
3. Close shut-off valve for boom hoist cylinder pressure
sender (Figure 2-13) — turn CLOCKWISE.
4. Place a suitable container under boom hoist cylinder
pressure sender to catch oil leakage.
5. Disconnect electric plug from boom hoist cylinder
pressure sender.
6. Slowly loosen boom hoist cylinder pressure sender only
enough to allow pressure to exhaust.
7. Remove boom hoist cylinder pressure sender.
8. Install new boom hoist cylinder pressure sender and
connect electric cord.
Pressure sender has pipe threads. Be sure to install
thread sealant.
9. Calibrate pressure senders before proceeding (see
procedure in Crane Operator’s Manual).
WARNING
High Pressure Oil Hazard!
Do not attempt to remove load drum, swing, track, or
boom hoist pump pressure senders unless following steps
are performed. High pressure oil will exhaust from
pressure sender ports.
WARNING
Falling Boom Hazard!
Do not remove boom hoist cylinder pressure sender until
following steps are performed. Boom will lower
uncontrolled.
FIGURE 2-13
Shut-Off Valve for Boom Hoist
Cylinder Pressure Sender
Turn CLOCKWISE to Close
P985
View Between Rear Drum and
Hydraulic Tank

Manitowoc 777 Specifications

General

Brand	Manitowoc
Model	777
Category	Construction Equipment
Language	English