DAF CF65, CF75, CF85 Series . Manual - part 1014

©

 200424

6-1

Tandem rear axle 1355T

DIAGNOSTICS

ΧΦ65/75/85 series

8

1

6. TANDEM REAR AXLE 1355T

6.1 FAULT-FINDING TABLE

SYMPTOM: NOISES IN REAR AXLE AND DRIVE ASSEMBLY

Possible cause

Remedy

Oil level too low

Top up oil

Incorrect oil viscosity

Drain oil and top up

Loosened attachment bolts or broken differential 

lock parts

Drain oil and check drained oil for presence of 

pieces of metal

Pinion-bearing play

Adjust and/or replace

SYMPTOM: OIL LEAK

Possible cause

Remedy

Oil level too high

Drain oil

Incorrect oil viscosity

Drain oil and top up

Leaking oil seal

Replace oil seal

Bleeding system blocked

Clean or replace the bleeding system

Oil leakage between the differential gear housing 

mating surfaces

Clean mating surfaces and apply new sealant

SYMPTOM: DIFFERENTIAL LOCK IS NOT FUNCTIONING

Possible cause

Remedy

No air pressure at engaging cylinder

Check compressed-air system

Defective pneumatic control

Check or replace pneumatic switch

Defective mechanical shift control

Check shift control

SYMPTOM: DIFFERENTIAL LOCK WARNING LAMP IS NOT FUNCTIONING

Possible cause

Remedy

Switch on cylinder fitted too high

Readjust switch

Switch on cylinder defective

Replace switch

Fault in electrical circuit

Check electrical circuit

DIAGNOSTICS

6-2

©

 200424

Tandem rear axle 1355T

1

ΧΦ65/75/85 series

8

©

 200424

7-1

Hydraulic lifting gear

DIAGNOSTICS

ΧΦ65/75/85 series

8

1

7. HYDRAULIC LIFTING GEAR

7.1 FAULT-FINDING TABLE

SYMPTOM: TRAILING AXLE DOES NOT LIFT, PUMP MOTOR IS NOT RUNNING

Possible cause

Remedy

Time between lowering and lifting < 2.5 minutes, 

causing the time relay to be constantly reset

After lowering the axle wait for more than 

2.5 minutes before putting the control switch into 

the "lifting" position.

Fault in electrical circuit

Check electrical circuit

Defective pump motor

Replace pump motor

SYMPTOM: TRAILING AXLE DOES NOT LIFT, PUMP MOTOR IS OPERATING BUT IS SWITCHED 

OFF IMMEDIATELY

Possible cause

Remedy

4/2 valve is not functioning

Check whether the 4/2 valve is activated

Connectors of 4/2 and 2/2 valves have been 

switched

Check the connection using the wire numbers

Piping kinked

Check piping

Pipe connections on the pump unit have been 

switched

Check pipe connections

SYMPTOM: TRAILING AXLE IS LIFTED PARTIALLY, PUMP MOTOR IS SWITCHED OFF

Possible cause

Remedy

Pressure switch activates at too low a pressure

Check pressure switch cut-out pressure and 

replace switch if necessary

Piping kinked

Check piping

Blocked trailing axle or mechanical linkage of lifting 

gear

Check the mechanical linkage

In cold weather conditions: oil of incorrect viscosity 

used

Drain the oil and fill the system with the specified oil

SYMPTOM: TRAILING AXLE IS LIFTED PARTIALLY, PUMP MOTOR CONTINUES TO OPERATE

Possible cause

Remedy

Not enough oil in the reservoir

Check oil level and top up, if necessary

Opening pressure of pressure relief valve too low 

or valve is leaking

Check the opening pressure of the pressure relief 

valve. Adjust or replace the valve

The 4/2 valve is leaking

Check the system pressure and subsequently the 

4/2 valve

Insufficient pump delivery due to leakage between 

pump and valve block, a worn pump or a defective 

motor

Check the system pressure, the pump and the 

pump motor

DIAGNOSTICS

7-2

©

 200424

Hydraulic lifting gear

1

ΧΦ65/75/85 series

8

SYMPTOM: PUMP MOTOR CONTINUES TO OPERATE WHILE THE TRAILING AXLE HAS BEEN 

FULLY LIFTED OR LOWERED

Possible cause

Remedy

Pressure relief valve setting too low

Check the opening pressure of the pressure relief 

valve and adjust the pressure-relief valve

Pressure switch is not functioning

Check the pressure switch and the wiring Replace 

the pressure switch, if necessary

Fault in electrical circuit

Check electrical circuit

SYMPTOM: TRAILING AXLE DOES NOT LOWER, PUMP MOTOR IS NOT RUNNING

Possible cause

Remedy

Fault in electrical circuit

Check electrical circuit

SYMPTOM: TRAILING AXLE IS NOT LOWERED, PUMP MOTOR IS OPERATING BUT IS 

SWITCHED OFF IMMEDIATELY

Possible cause

Remedy

2/2 valve is not functioning

Check whether the 2/2 valve is activated

Connectors of 2/2 and 4/2 valves have been 

switched

Check the connection using the wire numbers

Piping kinked

Check piping

SYMPTOM: TRAILING AXLE IS LOWERED QUICKLY, PUMP MOTOR IS NOT OPERATING AND 

RESERVOIR MAY FLOOD

Possible cause

Remedy

Fault in electrical circuit

Check electrical circuit

Defective pump motor

Repair or replace pump motor

SYMPTOM: TRAILING AXLE IS LOWERED AUTOMATICALLY ONCE LIFTED

Possible cause

Remedy

External oil leakage

Check piping, piping connections, pump unit and 

cylinders for leakage

Bad sealing of the 2/2 valve or of the non-return 

valve built into of the 2/2 valve

Check pump unit for internal leakage and 

subsequently inspect the 2/2 valve

Internal leakage of one of the cylinders

Check the cylinders for internal leakage