Electrohydraulic Pit Jacks - MAHA MPJ Series Original Operating Instructions

11.2

Electrohydraulic pit jacks

Malfunction
Pit jack does not respond no electricity
Piston rod does not
extend
Piston rod only extends
without load
Potentiometer shows no
effect (check with load)
52
Possible cause
Pump / motor defective
Control defective
Potentiometer defective
or position incorrect
Air in the system
Hydraulic valve / block
defective (rare)
Potentiometer defective
Amplifier card defective
Remedy
Check mains connection
Check fuses in the
control box
Check pump for running
noises
Check connections in the
control box (push-button)
Replace control box
(customer service)
Check the position of the
potentiometer
Check connections in the
switch box
Replace potentiometer
(customer service)
Loosen the bleed screw
(under the head plate)
and press the open
button for approx. 1 min
Remove the cover, turn
the potentiometer all the
way to the right, press the
up button and check the
valve coil for magnetism
using a metal object.
Turn the potentiometer to
the left and check
whether the magnetism
becomes stronger. If not,
check connections and
control unit, replace valve
coil if necessary
Replace hydraulic block
(customer service)
Replace potentiometer
(customer service)
Replace amplifier card
(customer service)
BA550001-en