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TROUBLESHOOTING
FIRST STEPS
•
Ensure the hydraulic flow and pressure from the base machine meets specifications (see "Hydraulic Circuit
Requirements" on page 8).
•
Inspect all hydraulic lines for kinks or damage. Replace any damaged hydraulic lines.
Symptom
Jaw will not move, moves too fast or
moves too slow.
Jaws drift open or closed
MDP cannot process or hold material
in it's jaws.
MDP will not rotate or rotation is very
slow/fast.
Jaw rotation drifts left or right.
The jaws don't shift speed when
closing.
Cause
No hydraulic flow to the MDP or
hydraulic flow is too high.
Check speed valve operation.
Base machine valve is open-center or
is faulty.
Speed valve needs adjustment.
The material is too big.
Speed valve needs adjustment.
Back pressure is too high.
Crossover relief valve is bypassing
oil or the manifold block has internal
leakage.
The rotation motor/gearbox is worn
out or has a broken output shaft.
Control valve ports are open with
spool in the neutral position. There is
leakage in the control valve spool.
Crossover relief valve is leaking or is
set too low.
Pilot valve pressure is too high.
Back pressure is too high in the base
machine return line.
remedy
Check the excavator hydraulic circuit
and ensure the hydraulic lines are not
kinked.
See "Adjusting the Speed Valve" on
page 23.
Use a closed-center spool. Use the
base machine manual to check the
valve.
See "Adjusting the Speed Valve" on
page 23.
Consult the factory.
See "Adjusting the Speed Valve" on
page 23.
Check all hydraulic lines. Ensure they
are not kinked and are the proper size.
Check the base machine circuit for a
restrictor.
Replace the crossover valve. Replace
the manifold block on the motor
and check cartridge valve seals for
damage.
Replace or reseal the motor/gearbox.
Inspect the base machine hydraulic
system.
Replace the crossover relief valve.
Adjust the pilot valve adjustment
counter clockwise in small
increments until issue is corrected
(see "Adjusting the Speed Valve" on
page 23).
Use larger diameter hydraulic lines
to minimize back pressure. Move
the main spool adjustment screw
clockwise in small increments until
the issue is corrected (see "Adjusting
the Speed Valve" on page 23).
MDP Operation & Maintenance Manual | 29
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