Manitowoc 777 User Manual

Reference Only
Manitowoc Published 10-01-12, Control # 044-05 v2 3-39
777 OPERATOR’S MANUAL OPERATING CONTROLS AND PROCEDURES
3
DISABLING AND ENABLING FREE FALL
Quick-disconnect couplers in hydraulic hoses to drum clutch
solenoid valves allow FREE FALL operation to be disabled at
either or both drum clutches.
When equipped with a luffing jib and free fall on the rear
drum, free fall must be disabled so the luffing jib cannot
lower uncontrolled.
Disabling Free Fall
Perform the following steps to disable free fall operation for
either or both load drums (Figure 3-23):
1. Stop engine.
2. For FRONT DRUM:
a. Disconnect clutch hose (F, View A or C) from
coupler (F1) at clutch solenoid valve.
b. Connect clutch hose (F, View A or C) to coupler (F2)
in tank return line.
3. For REAR DRUM:
a. Disconnect clutch hose (R, View B or C) from
coupler (R1) at clutch solenoid valve.
b. Connect clutch hose (R, View B or C) to coupler
(R2) in tank return line.
c. Install dust caps to keep unused couplers clean.
Enabling Free Fall
Perform the following steps to enable free fall operation for
either or both load drums (Figure 3-23):
1. Stop engine.
2. For FRONT DRUM:
a. Disconnect clutch hose (F, View A or C) from
coupler (F2) in tank return line.
b. Connect clutch hose (F, View A or C) to coupler (F1)
at clutch solenoid valve.
3. For REAR DRUM:
a. Disconnect clutch hose (R, View B or C) from
coupler (R2) in tank return line
b. Connect clutch hose (R, View B or C) to coupler
(R1) at clutch solenoid valve.
c. Install dust caps to keep unused couplers clean.
DANGER
Falling Jib Hazard!
When equipped with a luffing jib, do not operate rear drum
in FREE FALL mode. Luffing jib can lower uncontrolled if
this precaution is not taken. To prevent free fall from being
selected, disable free fall as instructed in this topic.
WARNING
Falling Load or Jib Hazard!
To prevent load or luffing jib from falling:
• Always stop engine before disconnecting and
connecting drum clutch hydraulic hoses.
• Do not operate crane unless drum clutch hydraulic
hoses are connected either to couplers at solenoid
valve or to couplers in tank return line.
Faulty clutch operation can occur if these precautions are
ignored. Load or luffing jib could fall.

Manitowoc 777 Specifications

General

Brand	Manitowoc
Model	777
Category	Construction Equipment
Language	English