CHECKS
Does system pressurize to 3,000 psi (207 bar) when moving mast switch to raise position?
PROBLEM 23
Mast cylinders will not raise or lower.
POSSIBLE CAUSES
Faulty control valve section; Low pump pressure; Bad pump; Switch failure;
Faulty counterbalance valve.
Yes
No
Repair
problem.
Are mechanical problems present at
mast assist cylinders?
Yes No
When moving mast switch, does accessory system pressure
increase?
Yes No
Adjust cylinder counterbalance
valve (See Section 2 - Adjusting
Counterbalance Valve.) Does
cylinder operate correctly?
Replace cylinder.
No
Check for 28 volts at mast power switch. (See Section 3 -
Checking Electrical Inputs/Outputs.)
Voltage
No Voltage
Are solenoids magnetized when
switch position is enabled?
Yes
No
Replace power switch.
Replace solenoid valve.
Check system pressure for 3,000 psi (207 bar).
Pressure Ok
Pressure not Ok
Repair or replace
control valve.
Check accessory/MAX-ER pump pressure output.
Repair or replace pump, if necessary.
Consult Manitowoc dealer or
Crane Care Lattice Team.
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