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).
Comparing brake lag and servo operation between the RRM and Hispano schemes.
| Identifier | ExFiles\Box 73\3\ scan0009 | |
| Date | 20th March 1924 | |
| R.R. 493A (20H) (D.A. 652 20-3-24) J.H.D. -2- EXPERIMENTAL REPORT. Expt. No. 9940 REF: Hs{Lord Ernest Hives - Chair}3/LG1.5.24. We have been able to find the lag on the RRM. scheme, but but it is very difficult to distinguish it. As we have pointed out previously, the lag is felt by the driver in two stages - first - the resistance of the pull off springs, and second - the resistance of the shoes on the drum before the extra wind-on due to the servo. On the Hispano, the 'Agreed' scheme or M.DES.60, the wind-on due to the servo operating, is considerable. We measure this by the amount the pedal goes beyond the point at which it arrives with pedal pressure only. On the RRM. scheme the wind-on felt on the pedal is very little. This is due to the fact that the wind-on of the front brakes is not felt on the foot pedal and as the whole of the foot pressure is applied to the rear brakes, the extra wind-on due to the servo is less. In the RRM. scheme we also have only one set of pull off springs and much less brake operating mechanism to move the with the foot. These two points we consider are definite advan- tages with the RRM. scheme. The problem with the RRM. scheme is the sog caused by the servo taking up the slack in the front brakes and the tendency for this to cause jaggers. Hs.{Lord Ernest Hives - Chair} | ||