3-22
BOOM CYLINDER HOLDING VALVE
A holding valve is directly connected to the base of the boom lift cylinder barrel and to the
base of the primary extension cylinder rod. These valves are designed to hold the boom
in position should loss of power or pressure line failure occur.
To check the boom lift cylinder holding valve, set the outriggers, place the boom in the
horizontal position over the front of the crane and raise rated load about one foot above
the ground using the boom lift cylinder (not the hoist). An example of rated load for the
IC-20 is 2,500 pounds (1110 kg) at an 8 foot (2.5 m) load radius, with outriggers
extended and the boom over the front. Turn the engine off and move the "BOOM" lever
to the "LOWER" position. If the boom moves down, adjust the holding valve.
WARNING
Before working on the holding valves or plumbing to the boom lift cylinders,
always relieve trapped pressure by lowering the boom fully, turning off the engine,
and cycling the "BOOM" lever.
To adjust the holding valve, loosen the jam nuts on the adjusting screw and tighten the
screw until unpowered boom movement stops. Retighten the jam nuts. If adjusting the
valve does not help, the cylinder may have internal leakage or the valve may be
malfunctioning.
EXTENSION CYLINDER HOLDING VALVE
A holding valve is directly connected to the base of the primary telescope cylinder rod.
The valve is designed to hold the boom in position should loss of power or pressure line
failure occur.
The holding valve should be checked with the boom elevated to the maximum angle and
the boom extended to the correct radius. A 4,000 to 5,000 pound (1810 to 2270 kg) load
on a 2-part line is required for this test. Use the hoist to lift this load about 6 inches (150
mm) above the ground. The radius of the test load should be within the rating on the
capacity chart. Use great care to prevent the load from hitting the crane.
Turn the engine off and pull the "TELESCOPE" lever to the "RETRACT" position. If the
boom retracts, the valve should be adjusted.
To adjust the holding valve, loosen the lock nut on the adjusting screw and tighten screw
until unpowered movement stops. Retighten the lock nut to hold the proper adjustment.
Summary of Contents for IC-20-1J
Page 6: ...1 2 DIMENSIONS AND ORIENTATION IC 20 1J Courtesy of Crane Market...
Page 7: ...1 3 TURNING DIMENSIONS Courtesy of Crane Market...
Page 25: ...2 11 Courtesy of Crane Market...
Page 26: ...2 12 Courtesy of Crane Market...
Page 36: ...Courtesy of Crane Market...
Page 44: ...3 8 IC 20 LUBRICATION CHART Courtesy of Crane Market...
Page 48: ...3 12 JIC SCHEMATIC Courtesy of Crane Market...
Page 50: ...3 14 STEERING SYSTEM Courtesy of Crane Market...
Page 52: ...3 16 IC 20 PROPULSION SYSTEM Courtesy of Crane Market...
Page 62: ...Courtesy of Crane Market...
Page 63: ...Powered by TCPDF www tcpdf org Courtesy of Crane Market...