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 system examination, detailing issues with the servo, drums, and linings, and proposing material changes.
| Identifier | ExFiles\Box 92\4\ scan0115 | |
| Date | 21th November 1935 | |
| -3- HS{Lord Ernest Hives - Chair}/APM.17/KW.21.11.35. We have examined the servo and it appears to be satisfactory. We have not been able to detect any fading in this component, as the scissor lever opening to give a certain load on the brakes varies hardly at all. (The servo is bound to fade when really hot, but we have not encountered this trouble). The V.M.30 linings get covered with dust, more than we have noticed on RAD.13, and their surface was slightly scored. The rear brake drums were very badly scored, chiefly due to the brass bonding in the linings. For this reason and also to see if we can reduce the fade, we are going to try F.B.A. zinc bonded linings on 35-MX.{John H Maddocks - Chief Proving Officer} We are also going to try some rivets made in a new non-scoring brass, to be supplied by Ferodo's. There is one other phenomenon we have noticed that is perhaps worthy of comment, and is due to the use of steel shoes. These have a very thin web section (to keep weight down), and owing to the lower conductivity of steel as against aluminium, it is possible during severe braking, such as during the descent of a steep hill fast, to get a big temperature difference between the inner and outer shoe radii. The greatest temperature difference we have measured is 140°C. This causes the shoes to arch themselves, and we estimate that with this temperature difference the centre of the shoe might expand from the axle .060" in respect to the shoe ends. This would cause a feeling of sponginess on the pedal, and would cause the drum to distort more than normally. To a lesser extent than this we must encounter this trouble during ordinary driving. HS{Lord Ernest Hives - Chair}/A.F. Martindale. | ||