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).
Tests and alterations performed on the RRM scheme 4-wheel brake system.
| Identifier | Morton\M20.2\ img023 | |
| Date | 20th March 1924 | |
| R.R. 493A (20H) (D.A. 652 20-3-24) J.H.D. ORIGINAL EXPERIMENTAL REPORT. Expl. No. 9940 4214 REF: Hs{Lord Ernest Hives - Chair}1/LG28 4.24. S E C R E T. EXPERIMENTS ON 4-WHEEL BRAKES. 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 BY.{R.W. Bailey - Chief Engineer} 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 1.3". 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 altering the lever on the front equaliser from 2.8 to 4.5". contd:- | ||