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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).
The performance and modifications of a 4-wheel brake system.

Identifier  ExFiles\Box 22\1\  Scan158
Date  28th April 1924
  
R.R. 403A (20M) (D.A. 652 20-3-24) J.H.D.

4214
9940
Expl. No. 4214
REF: HS{Lord Ernest Hives - Chair}1/LC28.4.24

EXPERIMENTAL REPORT.

S E C R E T.

EXPERIMENTS ON 4-WHEELBRAKES.

To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair}
c. to CJ. RG.{Mr Rowledge}
c. to DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer}
c. to EY. WOR.{Arthur Wormald - General Works Manager}

RRM. SCHEME.

The arrangement of the RRM. scheme as first fitted

up was as follows :-

Servo reduction 10 to 1.
Servo was of the first 'agreed' type with the driving
dogs to the 2 plates at a small radius.
The angle of the thread operating the servo was 45°.
The length of the lever operating the servo was 1.8".

The results of the first test on the road with the
RRM. scheme was that there was very little servo assistance and
therefore very little front braking and approximately the same
amount of foot pressure was required as on the standard 40/50.

We first of all increased the length of the lever
putting the end pressure on the servo, from 1.8 to 2.8. When
we tested this we still found that there was not sufficient
assistance from the servo. We then fitted the improved type
of servo doing away with the driving dogs at the small radius.
We found that this alteration increased the efficiency of the
servo considerably. We could then operate the brakes with
reasonably light pressure but nearly all the braking was on
the rear. We then altered the proportion of front and
rear braking by reducing the amount of servo assistance to the
back by altering the lever on the countershaft from 2.4 to 1.75".
At the same time, we increased the power of the front by alter-
ing the lever on the front equaliser from 2.8 to 4.5".

contd:-
  
  


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