Windshield Wiper

technical data -

Lucas Model SW4. Lucas part numbers 72542E (Briggs) and 72618B (Barker).

The wiper arm was listed as Lucas part number 735050 (although a different source lists it as 735098), the blade as 727707 and the grommet as 734181.

maintenance -

To be written...

problems -

The wiper motor is of the shunt wound type with a single field coil, and is mounted on the engine side of the dash. Incorporated with the motor is a reduction gearbox
which takes the drive to a continuously rotating final shaft; this shaft from the motor unit to the driving mechanism incorporates a rubber coupling.

A crank on the end of the shaft is connected by links to two clutch boxes on the screen rail which transmit motion to the wiper spindles. The switch is incorporated with one of the clutches.

The action of pulling out and turning the knob puts the blade on to the screen, engages the dog clutch and switches on the motor.

If the wiper fails to operate or operates unsatisfactorily, proceed as follows :
Ascertain if the battery is supplying current to the wiper by switching on and noting if the ammeter responds.
Examine the fuse protecting the wiper. If it has blown, examine the wiring for evidence of chafed leads or short
circuits. If, on replacing the fuse, it blows again, momentarily connect the motor directly to the battery and see if
wiper then operates satisfactorily.

Loose or Broken Connections
Examine connections from supply terminal in junction box to the motor, from the motor to the switch, and also examine the earthing lead from the switch.
Replace any leads which are badly worn or chafed. If necessary, fit protective tubing over the leads in the position where the original leads became chafed.

Switch Out of Adjustment
Remove the metal switch cover plate which is secured by two screws. Observe whether the switch contacts are opening and closing with the movement of the control knob,
and also whether the contacts are clean. The switch contacts should open just as the driving clutch disengages. If necessary, bend the switch blade to obtain this condition.
After resetting the switch, see that the contacts are effectively open when the wiper spindle is in the parked position.

Commutator Dirty
Remove the commutator end bracket by unscrewing the two countersunk screws and the screw with the barrel head. Clean the commutator by means of a cloth moistened with petrol.
Carefully remove any carbon dust from between the segments of the commutator. In reassembling, take care that the end bracket is lined up so that the armature rotates freely.

Brush Levers Stiff
If the brush levers are stiff on their pivots they should be freed by working backwards and forwards by hand and by applying a trace of thin machine oil.

Mechanism Binding
Remove the metal facia covering the driving links. Observe whether the links are fouling any part of the bodywork and also observe whether the swinging cranks
on the clutch mechanisms behind the control knob are clearing the clutch body at each end of the stroke.

Armature Bearings Binding
This may be due to lack of lubrication. Lubricators are provided on the motor unit through which a small quantity of a good grade thin machine oil may be applied.
Ascertain that a blow on the motor end bracket has not thrown the bearings out of line. A screw and lock nut are provided in the commutator end bracket to take up the end thrust of the armature. Under normal conditions this should not require adjustment.

Armature Damaged
If after following the preceding examination the wiper still does not operate, or its performance is unsatisfactory, the fault may be due to the armature.
Check the armature by substitution, and, if necessary, fit a replacement armature.

removal and fitting

click images below

other notes -

Late Barker-bodied LD10's appear to have been fitted with a model SW4 with Lucas part number 75066B.

Lucas part number 734652 is also listed as a Lanchester windshield wiper grommet. It is not known if this part is suitable or not.

Suitable replacement wiper grommets are available from Vintage Supplies Ltd. as part #538.02. They may also be able to supply wiper blades and arms.

diagrams -

All images are scanned from originals, wherever possible, at 100dpi (unless otherwise noted) and must be scaled when printed to preserve the original size (eg. scale up by 3 times for a 300dpi printer).

Note, however, that due to slight scaling inaccuracies during both the scanning and inevitably the printing, these images should be taken as an approximation for reference only.
In addition, drawings, measurements and notes of materials used are intended as a guide and aid to the restorer, and not necessarily a definitive, or even guaranteed correct, reference.

An example of a rubber peg used to hold the windscreen wiper blade in place (1 peg per blade).
Note that the length is not so important as the diameter and the notch (towards top right). There are many suitable replacement parts available with slight variations.

Example wipers removed from vehicles tend to vary in size from 8" to 11".

A 0.35" thick rubber (possibly 3/8" originally?) as fitted to the SW4.

links -

None yet.