CAUTION: THE WINDSCREEN WIPER MOTOR IS POLARITY SENSITIVE.
OBSERVE POLARITY WHEN PERFORMING ANY TESTING OF THE UNIT.
Data
Manufacturer - Lucas.
Type.. 14W
Lucas Part No. 75704
Stanpart No. 517621
Running current — after 60 seconds from cold with connecting rod removed
Normal speed 1.5 amp.
High speed 2.0 amp.
Running speed — final gear after 60 seconds from cold with connecting rod removed
Normal speed 46-52 r.p.m.
High speed 60-70 r.p.m.
Armature end float 0.002" to 0.008 in.
Brush length — normal speed — new 0.380"
renew if less than 3/16 in.
high speed — new 0.380"
renew if less than 0.280" (i.e. when narrow section is worn to step into full width section)
earth — new 0.380"
renew if less than 3/16 in.
Brush spring pressure — when compressed so brush bottom is aligned with brushbox slot end 5-7 ozs.
Maximum permissible force to move cable rack in tubing — arms and blades removed 6 lbs.
Description
Fig. 20. Windscreen wiper motor
The unit consists of a two speed permanent magnet motor and a gearbox unit which drives a cable rack mechanism.
Rotation of the motor armature is converted to a reciprocating motion of the cable rack by a single stage worm and gear, a connecting rod and a crosshead contained in a guide channel.
Two speed operation is provided by a third brush.
When high speed is selected the positive supply is transferred from the normal speed brush to the high speed brush.
A switching feature stops the blades in the park position irrespective of their position when the facia switch is selected OFF.
This is effected by a two stage limit switch unit attached to the gearbox.
The contacts are actuated by a cam on the final gear.
When the facia switch is selected OFF the motor will continue to run until the limit switch first stage contacts open.
A momentary period follows during which no contact is made.
The second stage contacts then close causing regenerative braking of the armature which maintains consistent parking of the blades.
Service
The windscreen wiper motor is greased during manufacture and no maintenance is required.
Adjust park position
The park position is not adjustable at the windscreen wiper motor.
The arms and blades may be repositioned on the splined wheelbox spindles to alter the swept arc.
Adjust armature end float
On a new windscreen wiper motor armature end float is normally controlled by a non adjustable thrust screw.
To check armature end float when a non adjustable thrust screw is fitted perform the following operation.
Position a feeler gauge between armature shaft and thrust screw. Push armature towards cover.
End float should be 0.002-0.008 in.
In the unlikely event of adjustment being required end float may be increased by fitting shim washer/washers under thrust screw head or reduced by mounting thrust screw in lathe and removing metal from underside of head.
If a service replacement armature is fitted it should be supplied with an adjustable thrust screw and lock nut as a boxing sundry.
To adjust armature end float when an adjustable thm.st screw and lock nut is fitted perform the following operation.
Slacken lock nut.
Screw thrust screw in until resistance is felt. Screw thrust screw out quarter of a turn—maintain in this position and tighten lock nut.
Repair
If the windscreen wiper motor is not operating correctly first check electrical supply of 12 volts on terminal 5 with normal speed selected and terminal 3 with high speed selected.
If electrical supply is satisfactory perform the following operations to determine if the fault is in the motor or in the cable 'rack and tubing assembly resulting in the motor being required to drive an excessive load.
Running Current
1. Remove four screws. Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways.
Remove washer (Fig. 23—item 19).
Carefully withdraw connecting rod.
Remove washer (17).
3. Connect ammeter suitable for running current (See Data) in supply circuit.
4. Allow motor to run for 60 seconds.
Ammeter reading should then be as given in Data for normal speed and high speed respectively.
If the reading is not as stated a fault in the motor is indicated.
Running Speed
1. Remove four screws.
Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways. Remove washer (Fig. 23—item 19).
Carefully withdraw connecting rod. Remove washer (17).
3. Allow motor to run for 60 seconds.
Speed of final gear should then be as given in Data for normal speed and high speed respectively.
If the speed is not as stated a fault in the motor is indicated.
Force to Move Cable Rack in Tubing
1. Remove four screws. Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways.
Remove washer (Fig. 23—item 19).
Carefully withdraw connecting rod.
Remove washer (17).
3. Remove arms and blades.
4. Attach a suitable spring scale to hole in crosshead.
Maximum permissible force to move cable rack in tubing is 6 lbs.
If the required force is greater than 6 lbs. a fault in the cable rack and tubing assembly is indicated.
Fig. 21. Connecting rod removed
A Park position—cable rack retracted 1 Crankpin
B Park position—cable rack extended 2 Cam
Fig. 22. Relationship of crankpin to cam for correct park position
Fig. 23. Windscreen wiper motor details
Disassemble Windscreen Wiper Motor
1. Remove four screws. Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways.
Remove washer (19).
Carefully withdraw connecting rod.
Remove washer (17).
3. Remove final gear shaft spring clip by withdrawing sideways.
Remove washer (13).
Ensure shaft is burr free and withdraw.
Remove dished washer.
4. Remove through bolts.
5. Carefully withdraw cover and armature about * in.
Continue withdrawal allowing brushes to drop clear of commutator.
Ensure that brushes are not contaminated with grease.
6. Pull armature from cover against action of permanent magnet.
7. Remove five screws to release brush assembly and limit switch unit.
Remove both units joined together by wires.
Assemble Windscreen Wiper Motor
NOTE: The following lubricants are used during assembly:
Shell Turbo 41 oil
Ragosine Listate grease
1. Position brush assembly and limit switch unit joined together by wires.
Secure with five screws.
2. Lubricate cover bearing and saturate cover bearing felt washer with Shell Turbo 41 oil.
Position armature to cover against action of permenent magnet.
3. Lubricate self aligning bearing with Shell Turbo 41 oil.
Carefully insert armature shaft through bearing.
Ensure that brushes are not contaminated with lubricant.
Push three brushes back to clear commutator.
4. Seat cover against gearbox.
Turn cover to align marks shown on Fig. 23.
Fit through bolts and torque load to 12-16 lb. in.
CAUTION: IF MARKS ARE NOT ALIGNED MOTOR WILL RUN IN REVERSE DIRECTION.
5. Determine if a non adjustable thrust screw or adjustable thrust screw and lock nut is fitted.
Refer to Adjust armature end float above and perform appropriate operation.
6. Lubricate final gear bushes with Shell Turbo 41 oil. Lubricate final gear cam with Ragosine Listate grease.
Fit dished washer with concave surface facing final gear.
Insert shaft.
Fit washer (13).
Fit spring clip by inserting sideways.
NOTE: The final gear is serviced only as an assembly.
Normally the crankpin mounting plate is not seperated from the moulded gearwheel.
If they should become parted assemble so relationship of crankpin to cam is as shown on Fig. 22.
7. Pack Ragosine Listate grease around worm gear, final gear and into crosshead guide channel.
8. Fit washer (17).
Lubricate final gear crankpin with Shell Turbo 41 oil and crosshead end of connecting rod including pin with Ragosine Listate grease.
Carefully insert connecting rod. Fit washer (19). Fit spring clip by inserting sideways.
9. Position gearbox cover. Secure with four screws.
Commutator
Clean commutator with petrol moistened cloth.
If the unit is in good condition it will be smooth and free from pits or burned spots.
If necessary polish with fine glass paper. If excessively worn replace armature.
Brushes
Clean brushes with petrol moistened cloth.
Ensure that the brushes move freely in the brushplate.
Check brush length—renew brush assembly if any brush is less than respective dimension given in Data.
Using a suitable push type spring scale check brush spring pressure.
Pressure should be as given in Data.
If pressure is low renew brush assembly.
Fig. 24. Component and switch wiring diagram
OBSERVE POLARITY WHEN PERFORMING ANY TESTING OF THE UNIT.
Data
Manufacturer - Lucas.
Type.. 14W
Lucas Part No. 75704
Stanpart No. 517621
Running current — after 60 seconds from cold with connecting rod removed
Normal speed 1.5 amp.
High speed 2.0 amp.
Running speed — final gear after 60 seconds from cold with connecting rod removed
Normal speed 46-52 r.p.m.
High speed 60-70 r.p.m.
Armature end float 0.002" to 0.008 in.
Brush length — normal speed — new 0.380"
renew if less than 3/16 in.
high speed — new 0.380"
renew if less than 0.280" (i.e. when narrow section is worn to step into full width section)
earth — new 0.380"
renew if less than 3/16 in.
Brush spring pressure — when compressed so brush bottom is aligned with brushbox slot end 5-7 ozs.
Maximum permissible force to move cable rack in tubing — arms and blades removed 6 lbs.
Description
Fig. 20. Windscreen wiper motor
The unit consists of a two speed permanent magnet motor and a gearbox unit which drives a cable rack mechanism.
Rotation of the motor armature is converted to a reciprocating motion of the cable rack by a single stage worm and gear, a connecting rod and a crosshead contained in a guide channel.
Two speed operation is provided by a third brush.
When high speed is selected the positive supply is transferred from the normal speed brush to the high speed brush.
A switching feature stops the blades in the park position irrespective of their position when the facia switch is selected OFF.
This is effected by a two stage limit switch unit attached to the gearbox.
The contacts are actuated by a cam on the final gear.
When the facia switch is selected OFF the motor will continue to run until the limit switch first stage contacts open.
A momentary period follows during which no contact is made.
The second stage contacts then close causing regenerative braking of the armature which maintains consistent parking of the blades.
Service
The windscreen wiper motor is greased during manufacture and no maintenance is required.
Adjust park position
The park position is not adjustable at the windscreen wiper motor.
The arms and blades may be repositioned on the splined wheelbox spindles to alter the swept arc.
Adjust armature end float
On a new windscreen wiper motor armature end float is normally controlled by a non adjustable thrust screw.
To check armature end float when a non adjustable thrust screw is fitted perform the following operation.
Position a feeler gauge between armature shaft and thrust screw. Push armature towards cover.
End float should be 0.002-0.008 in.
In the unlikely event of adjustment being required end float may be increased by fitting shim washer/washers under thrust screw head or reduced by mounting thrust screw in lathe and removing metal from underside of head.
If a service replacement armature is fitted it should be supplied with an adjustable thrust screw and lock nut as a boxing sundry.
To adjust armature end float when an adjustable thm.st screw and lock nut is fitted perform the following operation.
Slacken lock nut.
Screw thrust screw in until resistance is felt. Screw thrust screw out quarter of a turn—maintain in this position and tighten lock nut.
Repair
If the windscreen wiper motor is not operating correctly first check electrical supply of 12 volts on terminal 5 with normal speed selected and terminal 3 with high speed selected.
If electrical supply is satisfactory perform the following operations to determine if the fault is in the motor or in the cable 'rack and tubing assembly resulting in the motor being required to drive an excessive load.
Running Current
1. Remove four screws. Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways.
Remove washer (Fig. 23—item 19).
Carefully withdraw connecting rod.
Remove washer (17).
3. Connect ammeter suitable for running current (See Data) in supply circuit.
4. Allow motor to run for 60 seconds.
Ammeter reading should then be as given in Data for normal speed and high speed respectively.
If the reading is not as stated a fault in the motor is indicated.
Running Speed
1. Remove four screws.
Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways. Remove washer (Fig. 23—item 19).
Carefully withdraw connecting rod. Remove washer (17).
3. Allow motor to run for 60 seconds.
Speed of final gear should then be as given in Data for normal speed and high speed respectively.
If the speed is not as stated a fault in the motor is indicated.
Force to Move Cable Rack in Tubing
1. Remove four screws. Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways.
Remove washer (Fig. 23—item 19).
Carefully withdraw connecting rod.
Remove washer (17).
3. Remove arms and blades.
4. Attach a suitable spring scale to hole in crosshead.
Maximum permissible force to move cable rack in tubing is 6 lbs.
If the required force is greater than 6 lbs. a fault in the cable rack and tubing assembly is indicated.
Fig. 21. Connecting rod removed
A Park position—cable rack retracted 1 Crankpin
B Park position—cable rack extended 2 Cam
Fig. 22. Relationship of crankpin to cam for correct park position
Fig. 23. Windscreen wiper motor details
Disassemble Windscreen Wiper Motor
1. Remove four screws. Lift off gearbox cover.
2. Remove crank pin spring clip by withdrawing sideways.
Remove washer (19).
Carefully withdraw connecting rod.
Remove washer (17).
3. Remove final gear shaft spring clip by withdrawing sideways.
Remove washer (13).
Ensure shaft is burr free and withdraw.
Remove dished washer.
4. Remove through bolts.
5. Carefully withdraw cover and armature about * in.
Continue withdrawal allowing brushes to drop clear of commutator.
Ensure that brushes are not contaminated with grease.
6. Pull armature from cover against action of permanent magnet.
7. Remove five screws to release brush assembly and limit switch unit.
Remove both units joined together by wires.
Assemble Windscreen Wiper Motor
NOTE: The following lubricants are used during assembly:
Shell Turbo 41 oil
Ragosine Listate grease
1. Position brush assembly and limit switch unit joined together by wires.
Secure with five screws.
2. Lubricate cover bearing and saturate cover bearing felt washer with Shell Turbo 41 oil.
Position armature to cover against action of permenent magnet.
3. Lubricate self aligning bearing with Shell Turbo 41 oil.
Carefully insert armature shaft through bearing.
Ensure that brushes are not contaminated with lubricant.
Push three brushes back to clear commutator.
4. Seat cover against gearbox.
Turn cover to align marks shown on Fig. 23.
Fit through bolts and torque load to 12-16 lb. in.
CAUTION: IF MARKS ARE NOT ALIGNED MOTOR WILL RUN IN REVERSE DIRECTION.
5. Determine if a non adjustable thrust screw or adjustable thrust screw and lock nut is fitted.
Refer to Adjust armature end float above and perform appropriate operation.
6. Lubricate final gear bushes with Shell Turbo 41 oil. Lubricate final gear cam with Ragosine Listate grease.
Fit dished washer with concave surface facing final gear.
Insert shaft.
Fit washer (13).
Fit spring clip by inserting sideways.
NOTE: The final gear is serviced only as an assembly.
Normally the crankpin mounting plate is not seperated from the moulded gearwheel.
If they should become parted assemble so relationship of crankpin to cam is as shown on Fig. 22.
7. Pack Ragosine Listate grease around worm gear, final gear and into crosshead guide channel.
8. Fit washer (17).
Lubricate final gear crankpin with Shell Turbo 41 oil and crosshead end of connecting rod including pin with Ragosine Listate grease.
Carefully insert connecting rod. Fit washer (19). Fit spring clip by inserting sideways.
9. Position gearbox cover. Secure with four screws.
Commutator
Clean commutator with petrol moistened cloth.
If the unit is in good condition it will be smooth and free from pits or burned spots.
If necessary polish with fine glass paper. If excessively worn replace armature.
Brushes
Clean brushes with petrol moistened cloth.
Ensure that the brushes move freely in the brushplate.
Check brush length—renew brush assembly if any brush is less than respective dimension given in Data.
Using a suitable push type spring scale check brush spring pressure.
Pressure should be as given in Data.
If pressure is low renew brush assembly.
Fig. 24. Component and switch wiring diagram