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 testing standards, braking force calculations, and proposed brake shoe designs.
| Identifier | WestWitteringFiles\K\November1923\ Scan132 | |
| Date | 28th November 1923 | |
| R.R. 2x54 (100 T) (S.H. 159 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 TO HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} c.c. to:- SJ. BJ. c.c. to:- RM.{William Robotham - Chief Engineer} IVM. ORIGINAL R1/M28.11.23. re. BRAKES. 41559 X99260 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 this 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 feet. (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 a 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} | ||