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).
Four-wheel brakes, investigating a thumping sound and proposing friction-based solutions.
| Identifier | ExFiles\Box 73\3\ scan0236 | |
| Date | 13th October 1924 | |
| R.R. 493A (20H) (D.A. 652 20-3-24) J.E.H. EXPERIMENTAL REPORT. Expl. No. X9940 REF: Hs{Lord Ernest Hives - Chair}7/LG13.10.24. To R from Hs.{Lord Ernest Hives - Chair} c. to CJ. BJ. c. to H.{Arthur M. Hanbury - Head Complaints} Dag. c. to DY.{F R Danby} Wor.{Arthur Wormald - General Works Manager} S E C R E T. FOUR-WHEEL BRAKES. With reference to the complaint of front brakes causing a thump when the first application of the brake pedal is made. We find that this can be overcome if we introduce friction at the point where the links, suspending the balance lever, are hung from the gearbox. We have tried introducing friction surfaces with a the spring at this point. We found however that the surfaces were so small that we required very considerable pressure. We have treated a number of cars successfully; by reducing the bush so that the bolt cramped the links to the faces of the gearbox. We found no matter how much we tightened this bolt we could not get too much friction. The amount of friction required is 80 to 90 inch.lbs. There is very little movement on the joint if the brakes are correctly adjusted. The balance lever gives equal movement to the front and rear. The servo pressure alone is slightly greater to the front than the rear. Our tests have proved that wear is much more rapid on the rear so that we consider the present arrangement of balance lever is perhaps the best compromise. We recommend that we add friction to the links holding the balance lever, as soon as possible. Hs.{Lord Ernest Hives - Chair} | ||