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).
Comparative test report on 25 HP rear brakes, evaluating cast iron versus aluminium brake straps.
| Identifier | ExFiles\Box 120\1\ scan0096 | |
| Date | 21th July 1932 | |
| Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} From F.Dodd. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}FD.{Frank Dodd - Bodies}21.7.32. 25 HP. BRAKES. Owing to a number of complaints of rear brakes seizing up due to fast driving and very frequent application of the brakes, we have carried out some comparative tests with cast iron and aluminium brake straps. These tests were all carried out with ribbed brake drums. The brake levers were set 1 inch off the axle in the full on position, and a series of braking efforts from 50 M.P.H. down to 20 M.P.H. were recorded, reproducing driving fast in 3rd. speed down a winding lane. The table shows the difference between cast iron and aluminium straps with the number of braking efforts. A point of interest is that after the car is stopped the maximum amount of lost clearance at the levers is reached in 5 Mins. ALUMINIUM STRAPS. Reduction in Clearance at Levers. | No. of Brakes from 50 - 20MPH Off side- 7/16" | 15 Near Side- 1/2" | 5 mins. rest in between. Off Side- 5/8" | 30 Near Side- 5/8" | 5 mins. rest in between. Off Side- 3/4" | 45 Near Side- 13/16" | Total of 45 brakes. CAST IRON STRAPS. Reduction in Clearance at Lever. | No. of Brakes from 50-20 MPH. Offside- 1/8" | 15 Near Side- 1/8" | 5 mins. rest in between. Off Side- 3/16" | 30 Near Side- 3/16" | 5 mins. rest in between. Off Side- 1/4" | 45. Total of 45 brakes. Near Side- 3/8" | | ||