Bosch Rexroth Hagglunds DUc MS2 Installation & Maintenance Manual page 81

Causes Of Trouble And Its Effect In The Hydraulic Installation
Flow Control
Pressure Valves
Valves
1.Valve chatter due 1.The valve
to dirt on valve seal oscillates and
2.Insufficient excites other
damping control elements
(unsuitable flow)
into oscillation
3.Flow noises 2.Flow noises
when operating 3.Control system
4.Unsuitable oscillating
characteristic curve
5.Wrong design
1.Operating 1.Pressure losses
pressure set too excessive
low 2.False setting
2.Internal leakage 3.Valve defective
due to wear 4.Unsuitable type
3.Dirty or damaged
valve seat
4.Broken spring
5.Unsuitable type.
(setting too low)
1.Valve chatter due 1.Valve dirty
to dirt on valve 2.Pressure losses
seat or valve worn excessive
2.Insufficient
damping
(unsuitable type)
3.Excessive length
of undamped
remote control line
4.Unsuitable
remote- control
valve
Troubleshooting | Hägglunds DUc Drive unit
Directional
Fluid
Control Valves
1.Valve chatters 1.Cavitation
due to defective problems due to
solenoid or the low fluid level or
voltage is too low viscosity too high.
2.Valve defective (fluid temperature
due to dirt or wear is too low)
3.Flow through 2.Fluid is
valve is excessive contaminated
4.Pilot pressure and dirty leading
variations to damage and
5.On valves with
blockage of
adjustable damping equipment
the adjustment
3.Fluid foams
has not been
performed
6.Check the
electrical controls
1.Wrong switched 1.Viscosity too low,
position (eg causing excessive
pressureless) leakage.
2.Solenoid 2.Viscosity too high
defective causing excessive
3.Internal leakage flow resistance
due to wear 3.Fluid foams.
4.Excessive fluid
velocity
5.Spool jams
1.Valve chatters 1.Hydraulic fluid
due to defective dirty
solenoid or the 2.Hydraulic fluid
voltage is too low foams.
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. Unsuitable fluid
for the duty.
Output Drive
(motor)
1.Wear of running
surfaces
2.Control system
oscillating
1.Internal Leakage
2.Wear or running
surfaces
3.Excessive internal
friction causing low
efficiency
1.Stick-slip effect
due to friction
2.Operation
below minimum
recommended
motor speed.
RE 15326-WA, Version 06.2020, Bosch Rexroth AB
81/88
Others
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.Insufficient
load counter-
balance (eg
lowering control
valve)