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).
Summary of the development and testing of a four-wheel brake system, debating desired brake effect and servo multiplication.
| Identifier | ExFiles\Box 73\2\ scan0301 | |
| Date | 26th March 1924 | |
| X.9940 S E C R E T. To DA.{Bernard Day - Chassis Design} RG.{Mr Rowledge} ) E.{Mr Elliott - Chief Engineer} HS.{Lord Ernest Hives - Chair} ) FROM R.{Sir Henry Royce} c. to CJ. BJ. BY.{R.W. Bailey - Chief Engineer} PN.{Mr Northey} Mr. Claremont. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. FOUR WHEEL BRAKE SUMMARY. X.9940 In all the RR. cars tested I had the impression that they kept straight than the Hispano which was tested at WW. This is probably due to better equalisers and brake expanders. I am not in favour of sending out cars to give enormous brake effect for light foot pressure for 2 reasons :- (1) In an emergency a sudden application would certainly cause all wheels to skid, and steering control would be lost, jaggers possibly occur, and by the inertia of the wheels some-thing may be broken or fatigued to break later. (2) There will be a feeling that firm foot pressure is never needed and the car will run forward or backward when the side brake is removed or the car is required to stop to a few inches when brakes are lightly applied just as the car is coming to rest etc. Naturally if one knows ones car trouble can be avoided, but we ought to be like other cars. It is for this feature, and for simplicity, that I favoured RR. in preference to HS.{Lord Ernest Hives - Chair}CO. (They have now been combined.) To obtain this moderate effect and to make the difference as little as possible I suggest we endeavour to get a satisfactory result by concentrating the foot pressure on the rear brakes. The sketches enclosed shew the 2 arrangements which we have in hand and should be quite completed at WW. this week -> SEE ORIGINAL FOR SKETCHES. There is some uncertainty as to the desired pro-portion of servo multiplication. I suggested 3 times making 4 in all. Mr. Rowledge by an accident got twice what he was trying for. This pleased Mr. Hives but I felt it was danger-ous and feared breaking something, and for reasons given on page 1. The agreed scheme did not give enough. It should be tested by HS.{Lord Ernest Hives - Chair} what results were obtained and appear to be desired. Hispano was so variable in our test reports. In conclusion the clearing up and general improve-ment in the agreed scheme appeared excellent and highly desirable for our reputation. The four wheel brakes I also felt increased the safe average speed as stated first by PN.{Mr Northey} more than anything we have ever fitted. contd:- | ||