Rolls-Royce Archives
         « Prev  Box Series  Next »        

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 from Ferodo Limited about discrepancies in servo motor friction material test values, including a data table.

Identifier  ExFiles\Box 141\3\  scan0255
Date  2nd February 1934
  
Handwritten notes: GL{G. Linnett}609. 4 Per II Ex 10914 Nsh [illegible] x719 3869.

FERODO LIMITED
All Communications to be addressed to the Company.

TELEPHONE: 19 CHAPEL-EN-LE-FRITH (4 LINES)
TELEGRAMS: FRICTION, PHONE, CHAPEL-EN-LE-FRITH.

[Logo: FERODO REGD. TRADE MARK BRAKE & CLUTCH LININGS]

CODES: WESTERN UNION FIVE LETTER EDITION, BENTLEYS COMPLETE & 2ND PHRASE, MARCONI INTERNATIONAL, LIEBER'S CODE, LIEBER'S LATEST CODE, A.B.C. 5TH & 6TH EDITIONS.

CHAPEL-EN-LE-FRITH,
VIA STOCKPORT, ENGLAND.

February 2nd 1934

YOUR REF.
OUR REF. FJF/WAC.

Depots:-
LONDON
222, TOTTENHAM COURT RD W. 1.
ABERDEEN
26, GUILD STREET.
BELFAST
10 & 12, MONTGOMERY ST
BIRMINGHAM
CORPORATION ST
BRIGHTON
84, QUEEN'S ROAD.
BRISTOL
19, PARK STREET.
CARDIFF
39, CHARLES ST
DUBLIN
120, UPPER ABBEY ST
GLASGOW
70, WATERLOO ST
LEEDS
25, HUNSLET RD
LIVERPOOL
1, BERRY STREET.
MANCHESTER
2, CATHEDRAL ST
NEWCASTLE-ON-TYNE
WORSWICK CHAMBERS,
10, WORSWICK ST
OFF PILGRIM ST

Handwritten: GRY{Shadwell Grylls}

Messrs. Rolls-Royce Ltd.,
Derby.

For the attention of Mr. Grylls.

Dear Sirs,

We are in receipt of your letter of the 30th ultimo, and may say that in view of the discrepancies between the values of materials tested in the servo motor and those that obtain from other applications, we have always felt that the pressure of the spring could not apply to the friction surface in the case of your servo motor to the fullest extent possible - but that there is ground for this assumption is indicated by the values obtaining with the same discs with the pressure applied direct on a single surface by hydraulic cylinder and ram.

These figures are given in the table below, to which we have added a corresponding value for the similar [handwritten correction: same] materials as used in your servo motor.

Tests of Discs 4 5/8" O.D. 3 3/8" I.D. Speed from 0 to 250 r.p.m.

Pressure
Material | 300 lbs | 600 lbs | 800 lbs. | Corresponding values in servo motor. 775 lbs pressure.
---------------------|-----------|-----------|-----------|----------------------------------------------------------
Ferodo S.3914 | µ=.42 | .4 | .38 | .29
Ferodo Fibre | µ=.50 | .49 | .47 | .33
" HD.{Mr Hayward/Mr Huddy} | µ=.50 | .48 | .45 | .36
" M.R. | µ=.45 | .43 | .41 | .27
" VM/21 | µ=.39 | .36 | .33 | .24
" RAD.5 | µ=.45 | .42 | .4 | .29
" RAD.13 | µ=.54 | .5 | .45 | .32

Yours faithfully,
FERODO LIMITED.

[Illegible Signature]
CHIEF ENGINEER.

P.S. The writer was very interested in the cutting from the S.A.E. Journal which you kindly enclosed with your letter.
  
  


Copyright Sustain 2025, All Rights Reserved.    whatever is rightly done, however humble, is noble
An unhandled error has occurred. Reload 🗙