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).
Various braking system issues including servo wear, rear chunking, and potential solutions involving dash-pots and different materials.
| Identifier | ExFiles\Box 73\2\ scan0214 | |
| Date | 25th January 1924 | |
| X9940 To HS.{Lord Ernest Hives - Chair} RG.{Mr Rowledge} } FROM R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} } S E C R E T. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. RE. FRONT BRAKES. X.9940 Naturally we must expect trouble to be found in long distance testing, but the work of getting the above right seems to be getting along slowly. At the moment I can only suggest a very free working large size dash-pot on the pedal shaft or before the distributor that will prevent the extremely quick application of the brakes so as to avoid jaggers on the front axle, and chunking on the back. If this can be made consistent for temperature changes etc. by a suitable liquid then all should be well. One would prefer a thin oil that would not freeze, or change much in viscosity such as Fordclucth oil which is common to get. If this is used with a servo operating pull which requires a follow up then one dash pot should cure both faults. Unequal braking must be cured by keeping oil away from brakes - so necessary for many reasons. I agree with DA.{Bernard Day - Chassis Design} that steering towards the more effective brake with centre point steering probably caused by retardation being out of the centre of line of motion, and causes car to divert from line of wheel track like a boat when steered by overhanging oar does not follow keel. WEAR OF SERVO. This is a serious fault. You say the wear of this is greater than any other brake lining, which suggests we must increase leverage to rear brakes so as to require less torque from servo and decrease pull of actuating rod to servo or reduce servo's leverage. CHUNKING AT REAR. I agree that pull to servo cannot be made to take up slack in back brake ropes, but with pull requiring follow up and dash pot on pedal this should cure chunking. SCANDINAVIAN BELTING CO'S MATERIAL. It may be possible that this material is better for servo wear and brakes generally as it does not cut up the drum. It may wear better in the case of servo. It may not trouble you as regards change of co-efficient with temperature since back brakes may compensate by increasing their co-efficient with Ferodo, and also there is always the side lever to increase the braking of the back axle down-hill. Push on with EAC.4. This is the important one after EAC.3. is made passable. R.{Sir Henry Royce} | ||