Troubleshooting
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Hägglunds DOb, RE 15327-WA/05.2017, Installation and maintenance manual,
Bosch Rexroth AB
Causes Of Trouble And Its Effect In The Hydraulic Installation
Pressure Valves
Flow Control Valves
Directional Control
Valves
Fluid
output Drive
(motor)
others
1.Valve chatter due
to dirt on valve seal
2.Insufficient
damping (unsuitable
flow)
3.Flow noises when
operating
4.Unsuitable
characteristic curve
5.Wrong design
1.The valve
oscillates and
excites other control
elements into
oscillation
2.Flow noises
3.Control system
oscillating
1.Valve chatters due
to defective solenoid
or the voltage is too
low
2.Valve defective
due to dirt or wear
3.Flow through valve
is excessive
4.Pilot pressure
variations
5.On valves with
adjustable damping
the adjustment has
not been performed
6.Check the
electrical controls
1.Cavitation
problems due to
low fluid level or
viscosity too high.
(fluid temperature is
too low)
2.Fluid is
contaminated
and dirty leading
to damage and
blockage of
equipment
3.Fluid foams
1.Wear of running
surfaces
2.Control system
oscillating
1.Operating
pressure set too low
2.Internal leakage
due to wear
3.Dirty or damaged
valve seat
4.Broken spring
5.Unsuitable type.
(setting too low)
1.Pressure losses
excessive
2.False setting
3.Valve defective
4.Unsuitable type
1.Wrong switched
position (eg
pressureless)
2.Solenoid defective
3.Internal leakage
due to wear
4.Excessive fluid
velocity
5.Spool jams
1.Viscosity too low,
causing excessive
leakage.
2.Viscosity too high
causing excessive
flow resistance
3.Fluid foams.
1.Internal Leakage
2.Wear or running
surfaces
3.Excessive internal
friction causing low
efficiency
1.In the case of
pressure controls
there is a defect in
the open (or closed)
loop control circuit
2.Display
instruments are
defective
1.Valve chatter due
to dirt on valve seat
or valve worn
2.Insufficient
damping (unsuitable
type)
3.Excessive length
of undamped
remote control line
4.Unsuitable remote-
control valve
1.Valve dirty
2.Pressure losses
excessive
1.Valve chatters due
to defective solenoid
or the voltage is too
low
2.Valve defective
due to dirt or wear
3.Flow through valve
is excessive
4.Pilot pressure
variations
5. Adjustable
damping on valves,
has not been set
6.Check the
electrical controls.
1.Hydraulic fluid
dirty
2.Hydraulic fluid
foams.
1.Stick-slip effect
due to friction
2.Operation
below minimum
recommended
motor speed.
1.Insufficient load
counter-balance (eg
lowering control
valve)
1. Unsuitable fluid
for the duty.
