Voltage Regulator

technical data -

Lucas model RF91 (Briggs) and RF95 (Barker). Lucas service numbers 37031A and 37057E respectively.
Fuses are 25A (Lucas part #FA25).


maintenance -

Testing refer to link at Bottom of Page...


problems -

Over-tightening the screw terminals leads to stripped threads and damaged screw heads.

The metal strips on the underside of the unit have been known to snap at the rivets - probably as a result of over-tightening at the screw terminals.

Careless adjustment of the cut-out or regulator may leave either or both not functioning within their correct limits, which can lead to damage to the dynamo.


removal -

After disconnecting the wiring, remove 2 hex-headed screws (one either side).


other notes -

A replacement RF95 is available from Vintage Spares Ltd. as part number #RF95.

It is believed the RF91 was also fitted to the Singer 9hp & 10hp Roadster (1946-51).


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.

The regulator (located in the engine bay) is separated from the bulkhead by a flexible rubber? sheet as shown above.
The image shown is an RF95 gasket as found in the Barker-bodied LD10 - an RF91 gasket may differ in size and/or shape.


Control Box Tests