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).
Technical memo discussing issues and potential solutions for front brake thumps and overall brake inefficiency.
| Identifier | ExFiles\Box 84\2\ scan0131 | |
| Date | 22th March 1934 | |
| -3- Hm{Capt. W. Hallam - Head Repairs}/Gry.{Shadwell Grylls}10/KM.22.3.34. Front Brake Thumps. In order to overcome this trouble we have tried on 3-B-IV direct braking to all wheels to N.Sch.3879, with a pedal overall ratio of 25:1. Everybody who has tried the car dislikes this arrangement. The feel of the pedal is very spongy. It can always be pushed very nearly to the boards. We have fitted to 4-B-IV a scheme of GWH{George W. Hancock - Head Chateauroux}'s, EX.13184, that is an addition to the standard layout. The pedal applies the front brakes through a spring so that subsequent movement of the levers when the servo has taken up the sponge causes no movement of the pedal. This scheme fitted to 4-B-IV entirely removes the thumps that on this car are very bad with the existing system. Inefficiency of Brakes. We have not yet tried the servo in which the driving pins are replaced by a flexible plate. Judging by results on Peregrine, this should provide a reliable, efficient servo, so that without direct braking to all four wheels we shall be certain of sufficient front braking. We have already shown that the totally enclosed servo is an improvement as regards oil on the fabrics. Summarising therefore we prefer the present system of direct braking to the rear only, and consider that with the improved servo, larger drums, no sponge in the front operation, the pull of the rear ropes no longer below the axle, we shall have achieved complaint-free brakes. Hm{Capt. W. Hallam - Head Repairs}/H.Grylls. | ||