Service Manual and
Axial Piston Motors Series 20
Repair Instructions
L1003443
• Rev BA • Jun 2014
12
Transmission Operates in
one Direction Only
Troubleshooting
Check control
linkage
Repair
or replace
Inspect high pressure
relief valve
(see
page 13
)
Insert charge check valves
(see
Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Repair
or replace
(see
page 20,21
)
Inspect shuttle valve
in valve block
(see
page 14
)
Repair or replace
the valve block
(see
page 19
)
OK
Defective
Defective
OK
OK
Repair or replace
(see
Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Inspect control valve
(see
Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Replace control valve
(see
Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Defective
Defective
Defective
OK
System response is sluggish
Check charge
pressure
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Inspect
control valve
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Inspect motor
by-pass valve
(if used)
Replace
control valve
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
OK
Defective
OK
OK
Repair
or replace
Defective
Replace
transmission
(pump + motor)
OK
Inspect charge
pressure relief valve
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Repair or replace
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Inspect purge
relief valve
at motor
(see
page 21
)
Inspect charge
pressure relief valve
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Repair or
replace the
valve block
(see
page 19
)
Defective
Defective
Repair or replace
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Defective
Inspect
inlet filter
OK
OK
Replace
Clogged
Inspect
charge pump
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Repair or replace
(see
Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction
)
Defective
to low
in
neutral
to low in neutral and
forward or reverse
to low inforward
or reverse