Table of Contents
Pressure Valves
Flow Control Valves
1. Operating
1. Flow rate set too
pressure set too
low.
low.
2. Unsuitable
2. Internal Leakage
valve type
due to wear.
(operatingrange too
3. Dirty or damaged
low).
valve seat.
3. Valve blocked due
4. Broken spring.
to dirt.
5. Unsuitable type
(setting range too
low)
1. Constant delivery
1. Flow rate set too
flow is too high.
low (excessive pump
2. Undersized valve.
delivery through
3. Pressure setting
pressure-reliefvalve).
too high.
2. Valve defective.
4. Response time
too long.
1. Valve switches
too quickly.
2. Restrictors or
orifices are damaged
or missing.
Causes Of Trouble And Its Effect In The Hydraulic Installation
Directional Control
Valves
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. Leakage losses
too high.
2. Pressureless
circulation, if used,
fails to switch on.
3. Spool sticking.
1. Switching time
set too short.
2. Unsuitable
type of valve (the
openingcross-
sectional area
changes too
quickly).
Hägglunds DOb, RE 15327-WA/05.2017, Installation and maintenance manual, Bosch Rexroth AB
Fluid
output Drive
(motor, cylinder)
1. Viscosity too low,
1. Internal leakage.
causing excessive
2. Wear of running
leakage.
surfaces. 3.
2. Viscosity too high,
Excessive internal
causing excessive
friction, causing low
flow.
efficiency.
3. Fluid foams.
4. Seizure in
Hydraulic motor.
1. Viscosity too low,
1. Losses in
causing excessive
efficiency due to
leakage.
wear.
2. Viscosity too high,
2. Internal friction
causing excessive
too high (poor level
flow resistance.
of efficiency).
3. Fluid foams.
3. Internal leakage
losses.
1. Foaming of the
1. Excessive masses
hydraulic fluid.
or forces.
2. No damping.
Troubleshooting
75/80
others
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. 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. In accumulator
systems, throttle
valves have not been
fitted in front of the
switching valves.
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