New Holland WorkMaster 50 Service Manual page 424

Main lift system - Troubleshooting
Problem
The Rockshaft lifts jerkily Insufficient oil level in the tank
Rockshaft does not
operate
The rock shaft starts to
lift, but it stops as soon as
it feels the load, without
the functioning of the
over-pressure valve
The rock shaft does not
descend over its entire
travel
The rock shaft does not
descend
Lifting capacity does not
match that prescribed
The rock shaft supports
loads with difficulty
When the motor is off
With the arms raised at
backstop and with the
engine on, we have
verified a rhythmic
oscillation, with the
engine off the load does
not lower
The draft control does not
function, the rock shaft
raises and lowers only
with the position lever
The position control does
not function, the rock
shaft raises and lowers
only with the draft lever
Rockshaft does not lift
and the relief valve acts
with the possibility to
damage the pump
Hydraulic systems - Main lift system
Possible Cause
Pump inlet filter clogged
Infiltration of air into the pump inlet pipe
Differential valve blocked or dirty
Tension rod measurement (L) is not cor-
rect (Refer to Main lift system - Adjust
(35.100))
Faulty adjustment of the position control
lever (1)
Discharge valve blocked
Lever RD closed
Deterioration of the control valve seal rings Remove control valve and replace the ex-
Relief and safety valves out or calibration Control calibration of the valves
Poor pump efficiency
Excessive loss of oil from control valve
Piston gasket worn
Oil leakage from safety valve
Oil leakage from check valve
Incorrectly adjusted of position control lever
which, at maximum raised height, causes
the internal automatic backstop to function
Draft control lever is adjusted badly
Position control lever is adjusted badly
Pre selector i s fully closed
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Correction
Top up the level
Clean or replace the filter
Check the inlet pipe and any coupling and
gasket
Remove the control valve and unblock the
regulator piston
Adjust the draft control lever (Refer to Main
lift system - Adjust (35.100))
Adjust position control lever (Refer to Main
lift system - Adjust (35.100))
Remove control valve and unblock or clean
discharge valve
Turn lever RD in anti-clockwise
ternal seal rings
Replace the pump
Overhaul the control valve
Replace the gasket
Remove control valve and adjust valve
Remove the control valve and adjust valve
Adjust the position control lever (Refer to
Main lift system - Adjust (35.100))
Adjust the draft control lever ( Main lift sys-
tem - Adjust (35.100)).
Adjust the position control lever (Refer to
Main lift system - Adjust (35.100))
Unscrew fully the pre-selector (P) (Refer to
Main lift system - Adjust (35.100)).