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).
Comparing brake performance with latest modified leverage versus standard leverages.
| Identifier | ExFiles\Box 26\4\ Scan241 | |
| Date | 26th January 1924 | |
| R.B. 403A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. Expl. No. 9910 X9910 REF Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG26.1.24. 17 lbs.ft. at 500 drum r.p.m. without over-heating. LATEST MODIFIED LEVERAGE. (Instructions received by wire from DA.{Bernard Day - Chassis Design}) 17 lbs.ft. from servo is equivalent to 60.3 lbs.ft. at the Camshafts of the rear brakes (30.15 lbs.ft. per brake). This will produce a retarding torque of 885 lbs.ft. in the rear wheels or 635 lbs. at the tyres (brake rig data). Assuming front brakes to give a similar retarding torque. Total force at the tyres (retarding = 1270 lbs. Total guarantee wt. - 55 cwts. = 6150 lbs. Gradient at which 1270 lbs. will just hold a car of this weight = 1 in 4.4. Limiting gradient 1 in 4.4. WITH STANDARD LEVERAGES. Torque at the rear wheel brake camshafts = 31.7 lbs.ft. Torque retarding force available on four wheels = 670 lbs. This with a car of guarantee wt. will just hold the car on a 1 in 9.2 gradient. Limiting gradient = 1 in 9.2. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||