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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).
Letter to Ferodo Limited regarding the co-efficient of friction for 9L brake and clutch material.

Identifier  ExFiles\Box 32\2\  Scan020
Date  7th March 1921
  
X 3458

copy Ms.
Hs.{Lord Ernest Hives - Chair}

Hs{Lord Ernest Hives - Chair}
MAR 7 1921
RECEIVED

BY10-P7321.

X 3422
X 3458

Messrs. Ferodo Limited.,
Sovereign Mills,
CHAPEL-EN-LE-FRITH.

March 7/21.
Monday.

Attention of Mr Herbert Frood.

Dear Sir.,

REAR HUB AND BRAKE.

Referring to your favor of the 4th March, reference HF{H. W. Frost - Coachwork Inspector}/WD{Mr Wood/Mr Whitehead}, we note from your letter a point that had slipped our memory, namely, that the original 9L material did tend to drop the co-efficient of friction between the blue and red heat, and that in your later 9L material you have overcome this trouble.

I distinctly remember that the co-efficient of friction of the latest type 9L material increases, as you brought this point prominently to my notice in connection with Friction Clutches at your recent visit, but I had forgotten that in the original material the co-efficient of friction tends to fall slightly as the temperature rose.

After putting the matter before our Experimental Department, they agree that in view of the facts you put forward they have no need to feel alarmed in regard to the fact that the co-efficient of friction did tend to fall in the original 9L material they tested as the improvements you point out will remove the trouble altogether.

contd.
  
  


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