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).
Factors affecting Phantom braking distances, such as pedal operation speed and its influence on the servo system.
| Identifier | WestWitteringFiles\N\October1925-December1925\ Scan67 | |
| Date | 31th October 1925 | |
| R.R. 235A (100 T) (S.H. 159. 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 ORIGINAL TO HS.{Lord Ernest Hives - Chair} FROM DA.{Bernard Day - Chassis Design} DA{Bernard Day - Chassis Design}2/M31.10.25. PHANTOM BRAKING. X8470 We have recently had to supply Mr. Minchin with some pulling up distances for his Phantom in connection with an expected summons at Epsom. We can of course calculate the distance with theoretical accuracy, but there is one factor to determine which is uncertain, that is, the amount of pressure available for pulling on the front brakes. This is determined by the pressure required to skid the rear wheels, and it appears to us that this latter factor will be influenced by the speed with which the pedal is operated. A quick depression appears to allow the servo to transmit a greater pressure than a more gradual one because one has the influence of the fly wheel effect of the road wheels, engine, etc, and also there is a time interval while the weight of the car is transferred from the back to the front. It appears to us that there might be considerable differences in the pressure obtained on the front brakes by the speed of operation of the pedal. We know you do not approve of talking about pulling up distances, and we do not suggest that anything should be done, but if you have any information on this point it would be of interest to us? [STAMP: RECEIVED 2 NOV 1925] DA.{Bernard Day - Chassis Design} | ||