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 performance testing parameters and proposed shoe designs.
Identifier | ExFiles\Box 30\6\ Scan139 | |
Date | 28th November 1923 | |
To HS.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to CJ. BJ. c. to RG.{Mr Rowledge} DA.{Bernard Day - Chassis Design} c. to PN.{Mr Northey} X1559 R1/M28.11.23. RE. BRAKES. X.1559 X.9940 In your test of the value of brakes will you always, whenever possible, let us know the distance and weight or the horizontal effort that a given foot pressure (we take as 150 lbs.) will pull the car up. You can by a ready reckoner table tell the horizontal braking force. For instance we are asking you for 400 lbs. or about 33 1/3% of the load as the forward braking effect of each front wheel brake. Supposing then 40% of the weight of the car is on the front wheels we should get a pull up from 30 m.p.h. in 193 ft. (with front brakes only). The front wheel brakes backwards should be nearly twice the above because 50% of 40% = 20%, and only just enough to hold the car on a 1 in 5 gradient, which should be the least we ought to pass. We propose accomplishing this with one of our two schemes of brake shoes - 3 shoe pattern or 2 shoe floating fulcrum unequal shoes - i.e. forward 120°, back 120°, and 60° hinged. To get a standard of foot pressure we might for experiment purposely have a connecting link made with a suitable set up spring, this being coupled up between the foot pedal and the first motion shaft - i.e. the balancing gear. It would have to be a set up 300 lbs. spring with about 1" stroke at least. A compression spring in tube would probably be best. R.{Sir Henry Royce} | ||