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).
Brake judder and suggesting modifications to brake drum drain holes for improved water drainage.
| Identifier | ExFiles\Box 84\2\ scan0221 | |
| Date | 15th December 1934 | |
| Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} K/C1/DPB/15.12.34. Ref. B.191.AE. B.122.CR.{Mr Cra???ster / Mr Chichester} B.136.AH. BRAKE JUDDER. I daresay by now Brazier has returned to W after his visit to K regarding brake judder. I asked him to point out to you the question of the drain holes in the brake drums, having shewn to him the difference between the drain holes as drilled in the older type Bentleys as compared with the 3½-litre. B.122.CR{Mr Cra???ster / Mr Chichester} proved to be a rather stubborn case of low speed judder after washing and it occurred to me that an alteration of the inclination of these drain holes, so as to take advantage of any C.F. effect in giving efficient draining would be of assistance. On the older type Bentleys, there are four drain holes in the radius of the drum drilled at 45° to the vertical. (These drums are steel pressings.) I am fully aware of the difficulties that you are up against with the built up type of drum used on the 3½-litre, but there is one more point which I think is very important. Nowadays, most garages use high pressure washing plants. Situated as these holes are, they literally ask for a liberal dose of water, whereas if this drain hole was drilled at an angle of 45° it would to some extent retard the entrance of water into the drum at the onset and the C.F. effect on any water that had entered the drum would soon disperse that which still remained. I fully realise that the Production people may not like the idea of the hole at 45° owing to the position of the outside rib of the drum, but I do think these holes could be of more assistance if arranged to better effect. I must apologise for butting in on what is obviously not my province, but I do feel that any suggestion based on our experience here, might be adapted or might give you some line upon which to work towards a solution of the problem. K/CL. | ||