2-20
SAFETY DEVICES
There are safety devices on the IC-40 to maintain control of a load in case of power or
hydraulic line failure, or human error. The operator should understand the function and
operation of these devices so that a continual check on their performance can be made.
OUTRIGGER CYLINDER CHECK VALVE:
A double-acting check valve is flange-mounted on each of the outrigger cylinders. This valve
holds the outrigger in the extended position should power or hydraulic line failure occur. This
valve has no adjustment. If an outrigger creeps up while supporting a load, there is an internal
leak in the valve or in the outrigger piston seal. In either case, maintenance is required.
BOOM ELEVATION CYLINDER HOLDING VALVE:
A single-acting holding valve is built into the cylinder barrel. This valve holds the boom in the
elevated position should power or hydraulic pressure line failure occur. This valve is
adjustable to hold the desired load. If the boom creeps down with loads to maximum capacity,
this valve should be adjusted. If adjustment fails to correct the problem, there is an internal
leak in a holding valve or a hydraulic cylinder. Refer to the maintenance instructions.
BOOM EXTENSION CYLINDER HOLDING VALVE:
A single-acting holding valve is flange-mounted to the cylinder rod end. This valve holds the
cylinder in the extended position should power or hydraulic pressure line failure occur. This
valve is adjustable to hold the desired load. If the boom creeps in under load, this valve
should be adjusted. If adjustment fails to correct the problem, there is an internal leak in the
holding valve or the hydraulic cylinder. Refer to the maintenance instructions.
HOIST BRAKE AND HOLDING VALVE:
The hoist has an automatic brake in the gearbox and a holding valve mounted directly on the
hoist motor to hold the load. A clutch in the gearbox allows the winch to turn freely in the
RAISE direction. The brake is pilot-released in the LOWER direction, and should allow
smooth stops of a load on the hoist.
ANTI-TWO-BLOCK DEVICE:
The anti-two-block device prevents damage to hoist rope or machine components from
accidentally pulling load hook against boom tip. There is a pivot arm at the boom tip that is
moved upward by the load hook as it approaches the boom tip. An electric switch connected
to a hydraulic solenoid valve dumps the HOIST RAISE, TELESCOPE EXTEND, BOOM
LOWER, SWING LEFT, and SWING RIGHT circuits. No other circuits are affected. These
circuits are returned to normal operation by operating the HOIST LOWER, TELESCOPE
RETRACT, or BOOM RAISE control.
An emergency override switch is provided so the boom can be operated in case of
system failure. This key-operated switch is located under the instrument panel.
W A R N I N G
We recommend the emergency override switch be used with discretion. Improper or careless
use of this switch can cause damage to the crane and endanger people and property. The
operator who uses this key in an emergency should use good judgment.
W A R N I N G
Even though the crane is equipped with an anti-two-block device, we strongly recommend that
the operator always watch the downhaul and stop lifting before two-blocking occurs. Two-
blocking can break the load hoist rope and let the load fall. This could cause death or serious
injury.
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