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 performance issues, proposing modifications to drums and linings to manage heat.
| Identifier | ExFiles\Box 120\1\ scan0300 | |
| Date | 21th February 1941 | |
| Rm.{William Robotham - Chief Engineer}3/ET.21.2.41 - 2 - in a couple of minutes whether the set-out has any prospect of being some good. When we get the light alloy drums, I am certainly in favour of casting ribs on the back plate, as additional cooling surface. I am rather afraid, however, that the trouble is due to the intense heat at the surface of the lining, due to the high unit pressure and that, increasing the heat capacity of the drums will not overcome the trouble, nor will increasing its cooling surface, though both will help. I think, therefore, as an alternative, we should get some drums made up with 25% increase in width, with shoes and lining to match. I am sure that this would make an enormous difference. We can put these on our cars without increasing the drag, by modifying the wheel arches if the increase in width causes a foul. When we have got something that will stand up to ordinary driving, then I am prepared to go for a different lining to satisfy the customer who has no consideration for his car. I do not mind much if it squeaks, because this would at least draw the gentleman's attention to the fact that he is being punished for his eccentric behaviour. We have got to remember that 12-B-V, which is the Senior Rango model of which I expect to sell the greatest number, has brake drums with reduced capacity which have proved themselves to be perfectly satisfactory, even though they are being used steel wheels. In fact I have seldom driven a car which has consistently had better brakes. I think you should certainly find out why the clearance between the lining and the drum has such a large effect on your tests, because, if your cooling figures mean anything, the lining clearance might contribute towards better life. Have you a list of linings from Ferodo shewing the resistance to heat at elevated temperatures, in order of merit? Rm.{William Robotham - Chief Engineer} | ||