Bosch rexroth A21VG 10 Series - Malfunction table

Troubleshooting 49/56
RE 93223-01-B/09.2020, A21VG Series 10, Bosch Rexroth Corporation
14.2 Malfunction table
Table 13: Axial piston unit malfunction table
Malfunction Possible cause Remedy
Unusual noises Drive speed too high. Machine/system manufacturer.
Wrong direction of rotation. Ensure correct direction of rotation.
Insufcient suction conditions, e.g. air in
the suction line, insufcient diameter of
the suction line, viscosity of the hydraulic
uid too high, suction height too high,
suction pressure too low, contaminants
in the suction line (only relevant for the
version with boost pump).
Machine or system manufacturer
(e.g. optimize inlet conditions, use suitable
hydraulic uid).
Completely air bleed axial piston unit, ll
suction line with hydraulic uid.
Remove contaminants from the suction
line.
Improper mounting of the axial piston unit. Check the mounting of the axial piston
unit according to the specications of the
machine/system manufacturer. Observe
tightening torques.
Improper mounting of the attachment
parts, e.g. coupling and hydraulic lines.
Fix attachment parts according to the
information provided by the coupling or
tting manufacturer.
Pressure-relief valves on axial piston unit. Air bleed the axial piston unit
Check viscosity of the hydraulic uid
Contact Bosch Rexroth Service.
Pressure-relief valve of the axial piston unit
(boost pressure, high pressure).
Air bleed the axial piston unit
Check viscosity of the hydraulic uid
Contact Bosch Rexroth Service.
Mechanical damage to the axial piston unit
(e.g. bearing damage).
Exchange axial piston unit,
contact Bosch Rexroth Service.
No or insufcient ow Faulty mechanical drive
(e.g. defective coupling).
Machine/system manufacturer.
Drive speed too low. Machine/system manufacturer.
Insufcient suction conditions, e.g. air in
the suction line, insufcient diameter of
the suction line, viscosity of the hydraulic
uid too high, suction height too high,
suction pressure too low, contaminants
in the suction line (only relevant for the
version with boost pump).
Machine or system manufacturer
(e.g. optimize inlet conditions, use suitable
hydraulic uid).
Completely air bleed axial piston unit, ll
suction line with hydraulic uid.
Remove contaminants from the suction
line.
Hydraulic uid not in optimum viscosity
range.
Use suitable hydraulic uid (machine/
system manufacturer).
External control of the control device
defective.
Check external control (machine/system
manufacturer).
Insufcient pilot pressure or control
pressure.
Check pilot pressure or control pressure,
contact Bosch Rexroth Service.
Malfunction of the control device or
controller of the axial piston unit.
Contact Bosch Rexroth Service.
Wear of axial piston unit. Exchange axial piston unit,
contact Bosch Rexroth Service.
Mechanical damage to the axial piston unit. Exchange axial piston unit,
contact Bosch Rexroth Service.