Bosch Rexroth Hagglunds DUc MS2 Installation & Maintenance Manual page 83

Causes Of Trouble And Its Effect In The Hydraulic Installation
Pressure Valves Flow Control
Valves
1. Operating 1. Flow rate set
pressure set too too low.
low. 2. Unsuitable
2. Internal Leakage valve type
due to wear. (operatingrange
3. Dirty or too low).
damaged valve 3. Valve blocked
seat. due to dirt.
4. Broken spring.
5. Unsuitable type
(setting range too
low)
1. Constant 1. Flow rate set
delivery flow is too too low (excessive
high.
pump delivery
2. Undersized through pressure-
valve. relief valve).
3. Pressure setting 2. Valve defective.
too high.
4. Response time
too long.
1. Valve switches
too quickly.
2. Restrictors
or orifices are
damaged or
missing.
1.Sequence valve
or shut-off valve
has wrong setting.
Troubleshooting | Hägglunds DUc Drive unit
Directional Fluid
Control Valves
1. Wrong switched 1. Viscosity too
position. low, causing
2. Solenoid excessive leakage.
defective. 2. Viscosity too
3. Internal leakage high, causing
due to wear. excessive flow.
4. Excessive fluid 3. Fluid foams.
velocity.
5. Spool jams or
sticks.
6. Manually
operated valves are
not open.
1. Leakage losses 1. Viscosity too
too high. low, causing
2. Pressure less oil excessive leakage.
circulation if used, 2. Viscosity too
fails to switch on. high, causing
3. Spool sticking. excessive flow
resistance.
3. Fluid foams.
1. Switching time 1. Foaming of the
set too short. hydraulic fluid.
2. Unsuitable
type of valve
(the opening
cross-sectional
area changes too
quickly).
Output Drive
(motor, cylinder)
1. Internal leakage.
2. Wear of running
surfaces.
3. Excessive
internal friction,
causing low
efficiency.
4. Seizure in
Hydraulic motor.
1. Losses in
efficiency due to
wear.
2. Internal friction
too high (poor
level of efficiency).
3. Internal leakage
losses.
1. Excessive
masses or forces.
2. No damping.
RE 15326-WA, Version 06.2020, Bosch Rexroth AB
83/88
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. Pressure less
oil circulation
when the pump is
running.
3. Insufficient
hydraulic fluid.
4. Coolant valve
failed.
5. Thermostat set
too high.
6. Fan not switched
on.
7. Ambient too
high.
8. Deposits in
radiator.
1. In accumulator
systems, throttle
valves have not
been fitted in front
of the switching
valves.
1. Accumulator
precharge pressure
is too low.
2. Bladder
defective.
3. Pressure switch
differential set too
low.
4. Pressure switch
set incorrectly.