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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Fault with the ignition warning light on 25 & 30 HP cars causing the dynamo not to charge.

Identifier  ExFiles\Box 163\7\  img289
Date  14th July 1936
  
To Rgr
C. to N-g-by.{R.W. Bailey - Chief Engineer}
C. to Wst.

86013.

Cricklewood,
14th July, 1936.

Ignition Warning Light - 25 & 30 HP. R.R. Cars
GTL-3 & GUL-48.

In two cases here of Dynamo not charging, the trouble has been traced to the ignition warning lamp. The brass bulb holder stands proud of the ebonite carrier when the bulb is screwed home, and when the whole unit is pressed into the socket, this holder comes into contact with the shield 'A', which is not central with the socket 'B'. This earths the shunt winding of the cut-out and prevents the cut-out points closing, so failing to make the dynamo to battery circuit.

The trouble can be prevented in spite of the shield 'A' not being central with the holder 'B' if the brass bulb holder is countersunk below the ebonite and the length of the ebonite so arranged that when the unit is pressed home it bears against the shoulder 'C' and not against the shield, leaving clearance at this point.

If this is a new type holder or dash unit the matter should be looked into immediately.

[Handwritten note]
C.A.P. Is this being attended to by D.O. ? WGH

[Typed signature]
HS{Lord Ernest Hives - Chair}/J.B.Dixon.

[Blueprint text]
FRONT OF DASH.
LIGHTSHIELD 'A'
NOT CENTRAL
WITH SOCKET 'B'.
CONTACT BETWEEN BRASS BULB HOLDER & METAL SHIELD 'A'.
- 7/8" -> C
  
  


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