Troubleshooting
75/80
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, cylinder)
others
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 range too
low)
1. Flow rate set too
low.
2. Unsuitable
valve type
(operatingrange too
low).
3. Valve blocked due
to dirt.
1. Wrong switched
position .
2. Solenoid
defective.
3. Internal leakage
due to wear.
4. Excessive fluid
velocity.
5. Spool jams or
sticks.
6. Manually
operated valves are
not open.
1. Viscosity too low,
causing excessive
leakage.
2. Viscosity too high,
causing excessive
flow.
3. Fluid foams.
1. Internal leakage.
2. Wear of running
surfaces. 3.
Excessive internal
friction, causing low
efficiency.
4. Seizure in
Hydraulic motor.
1. Conditions for
starting not fulfilled.
2. Electrical lines
opencircuit
3. Signalling
elements, such
as pressure or
limit switches,
are defective,
wrongly set, or not
connected.
1. Constant delivery
flow is too high.
2. Undersized valve.
3. Pressure setting
too high.
4. Response time
too long.
1. Flow rate set too
low (excessive pump
delivery through
pressure-reliefvalve).
2. Valve defective.
1. Leakage losses
too high.
2. Pressureless
circulation, if used,
fails to switch on.
3. Spool sticking.
1. Viscosity too low,
causing excessive
leakage.
2. Viscosity too high,
causing excessive
flow resistance.
3. Fluid foams.
1. Losses in
efficiency due to
wear.
2. Internal friction
too high (poor level
of efficiency).
3. Internal leakage
losses.
1. Cooling
performance
inadequate.
2. Insufficient
Hydraulic fluid.
3. Cooling set point
set
too high.
4. Fan not switched
on.
5. Ambient
temperature too
high.
6. Deposits in
radiator.
1. Valve switches
too quickly.
2. Restrictors or
orifices are damaged
or missing.
1. Switching time
set too short.
2. Unsuitable
type of valve (the
openingcross-
sectional area
changes too
quickly).
1. Foaming of the
hydraulic fluid.
1. Excessive masses
or forces.
2. No damping.
1. In accumulator
systems, throttle
valves have not been
fitted in front of the
switching valves.