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).
Cause and potential solutions for 'brake thumps' on 20-HP cars.
| Identifier | ExFiles\Box 5\3\ 03-page268 | |
| Date | 29th October 1928 | |
| -DY.{F R Danby} C. HS.{Lord Ernest Hives - Chair} Y5420 EP{G. Eric Platford - Chief Quality Engineer}15/H29.10.28. re. 20-HP. BRAKE "THUMPS". The above is at present rather a general complaint and appears to be a trouble which takesplace on some new 20-HP cars, shortly after delivery to customer. There is certainly a tendency for this to take place on some chassis on test, and as far as possible this is made reasonable by attention to the servo, hand brakes and damping of the swinging arm. Our tester Wright, however, points out in regard to the latter feature the present swinging arm may be working like a Smith Shock absorber, more poundage in one direction than the other, and at present the light poundage is in the direction of the pull and the heavy poundage in the direction of the release. He suggests that the fixing of this swinging arm should be reversed so that the slot is on the opposite side, so as to reverse the action above described. We also suggest that more consistent action might be obtained by fixing a lubricator on to this swinging arm. There was a lubricating hole originally, but this was done away with owing to grit getting into same. In some bad cases of this taking place in service we have only been able to overcome the trouble by definitely reducing the effectiveness of the front brakes. Could we not push for standardising and fixing of the front axle support to this chassis, similarly as is applied on the Phantom Chassis. We suggest that this should be done in preference to reducing the effectiveness of the front brakes. Although we do not claim that this scheme will necessarily cure the thumps, it may be a help, and in any case it certainly will generally improve the steering and riding of the front of the 20-HP car which is now not as good as the present standard Phantom. EP.{G. Eric Platford - Chief Quality Engineer} | ||