54/56 Troubleshooting
Bosch Rexroth AG
, MCR Series 30, 31, 32, 33 and 41, RE 15215-01-B/11.2015
Table 12: Radial piston motor malfunction table
Fault
Possible cause
Remedy
Insufficient brake torque
Excessive pressure in brake release chamber
(disc brake).
Check brake pressure in engaged state per
machine manufacturer’s specification. If too high,
check control valve and drain lines to reservoir,
and repair/replace, or remove blockage, as
necessary.
Motor case drain pressure too high, causing
partial release of brake (disc brake).
Check case pressure versus machine
specification. If too high, check drain line for
blockages.
Worn brake linings or discs.
Replace brake shoes or brake discs as necessary.
In case of wear on parking brake (disc brake),
investigate cause, as brake should not be used
dynamically and should not wear.
Anti-stick/slip additive in hydraulic fluid (disc
brake).
Drain and flush system and refill with hydraulic
fluid without additive. Strip and thoroughly clean
all motor components, replacing all brake discs.
Insufficient brake actuation pressure (dynamic
brake).
Check pressure versus machine specification
and check pressure source. Repair or replace
components as required.
Drum brake not run in.
Carry out drum brake run-in procedure per motor
data sheet.
Brake does not release
Brake release pressure too low (disc brake).
Check brake release pressure versus machine
manufacturer’s specification and adjust, repair or
replace pressure source as necessary. If pressure
source OK, strip down brake and check and
replace brake seal as necessary.
Brake piston or seals damaged (disc brake).
Replace brake piston or seals as required.
Brake plates seized (disc brake).
Strip and inspect brake, replacing parts as
required. If seized, investigate cause of seizure,
as parking brake should not be used dynamically.
Incorrect function of 2-speed
control (where fitted)
2-speed control pressures incorrect.
Check shifted and non-shifted control pressures
versus machine specification. Check, and repair
or replace control components as necessary.
Integrated 2-speed valve damaged.
Strip 2-speed valve and check all components,
including bore in motor housing. Remove any
contamination and replace components or motor
housing as necessary.
Motor case drain pressure too high, causing
partial or non-shifting of 2-speed valve.
Check case pressure versus machine
specification. If too high, check drain line for
blockages.
Incorrect signal from speed
sensor (where fitted)
Speed sensor or target disc damaged.
Check output from speed sensor on oscilloscope
(should give correct number of pulses per motor
revolution per specification). Replace sensor or
target disc as necessary.
