DAF LF45, LF55 Series. Manual - part 224

©

 200508

2-1

Pneumatic gearbox control

DIAGNOSTICS

ΛΦ45/55 series

3

1

2. PNEUMATIC GEARBOX CONTROL

2.1 FAULT-FINDING TABLE

COMPLAINT: NOT POSSIBLE TO ENGAGE HIGH OR LOW RANGE

Possible cause

Remedy

Air pressure too low

Check air supply of circuit 4

Neutral position valve defective or incorrectly 

connected

Connect valve properly or replace

Faulty downshift protection valve

Replace valve

Defective high/low range engaging cylinder

Check cylinder and replace if necessary

COMPLAINT: HIGH/LOW RANGE ENGAGING CYLINDER ENGAGES LOW AT TOO HIGH A 

SPEED

Possible cause

Remedy

Incorrect VIC frequency value

Adjust value

COMPLAINT: HIGH OR LOW RANGE ENGAGING IS SLOW

Possible cause

Remedy

Air pressure too low

Check air supply of circuit 4

Piping blocked

Check piping and clean, if necessary

Defective neutral position valve

Replace valve

COMPLAINT: HIGH/LOW RANGE ENGAGING CYLINDER WORKS THE WRONG WAY ROUND

Possible cause

Remedy

Air pipes on the high/low range engaging cylinder 

are incorrectly connected

Connect engaging cylinder air pipes correctly

COMPLAINT: NOT POSSIBLE TO ENGAGE LOW RANGE

Possible cause

Remedy

VIC defective

Check VIC and replace, if necessary

Incorrect vehicle speed signal

Check vehicle speed signal

DIAGNOSTICS

2-2

©

 200508

Pneumatic gearbox control

1

ΛΦ45/55 series

3

©

 200508

3-1

Mechanical gearbox

DIAGNOSTICS

ΛΦ45/55 series

3

1

3. MECHANICAL GEARBOX

3.1 FAULT-FINDING TABLE

COMPLAINT: ENGAGING GEARS IS HEAVY

Possible cause

Remedy

Gearbox oil level too low

Top up oil level

Oil with incorrect specification in the gearbox

Fill gearbox with oil of correct specification

Problem in mechanical gearbox control

See "Mechanical gearbox control" fault-finding 

table

Clutch plate is not released

See "Clutch" fault-finding table

COMPLAINT: GEARS CANNOT BE ENGAGED

Possible cause

Remedy

Retaining element fitted too deep

Check/repair retaining elements

Problem in mechanical gearbox control

See "Mechanical gearbox control" fault-finding 

table

Range-change switch does not work properly

See "Pneumatic section of gearbox control" fault-

finding table

COMPLAINT: GEARBOX JUMPS OUT OF GEAR

Possible cause

Remedy

Adjustment of gearshift cover on gearbox

Mount gearshift cover on gearbox without any play

Defective retaining element or wrong type of 

retaining element fitted in gearshift cover

Replace retaining element or fit other type of 

retaining element

Problem in mechanical gearbox control

See "Mechanical gearbox control" fault-finding 

table

COMPLAINT: SINGLE H BECOMES DOUBLE H

Possible cause

Remedy

Locking plate in control cover not positioned 

correctly

Check assembly of control cover

DIAGNOSTICS

3-2

©

 200508

Mechanical gearbox

1

ΛΦ45/55 series

3