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).
The causes and elimination of brake jaggers.
| Identifier | ExFiles\Box 30\6\ Scan144 | |
| Date | 12th July 1923 | |
| R.R. 493A (40 H) (EL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} -2- EXPERIMENTAL REPORT. Expl. No. 9940 REF: HS{Lord Ernest Hives - Chair}4/4/C1L.1.24. This week we have received from DA.{Bernard Day - Chassis Design} a scheme for reducing the power of the servo by increasing the wind-off and leverages. When this is completed it will be fitted in place of our temporary arrangement. BRAKE JAGGERS. The following is a report on experiments carried out on brake jaggers. To produce jaggers easily the brake must be applied suddenly, not necessarily with high pressure but the pedal has to be flicked. Jaggers can always be avoided if the brake is applied gradually no matter what pressure is used. The condition of the brakes themselves make a big difference as regards whether jaggers are easily produced or not. In order to produce jaggers the brakes must be solid and effective - if the brakes are spongy or the trailing shoe comes into contact with the drum before the wrapping shoe, jaggers will not occur. Whilst jaggering takes place the pedal pressure is constant. (It is possible to keep a car jaggering continuously if the engine power is left off). If more pressure is applied, jaggers will cease and the wheels lock. This applies to really effective brakes. The pressure required to produce jaggers appears to be such that it is not quite sufficient to cause the wheels to skid but it is sufficient momentarily to lock the Ferodo to the brake drum thus allowing the whole of the axle to start to revolve round the front end of the radius rods. So far, the only way in which we have been able to totally eliminate jaggers has been with the torque arm, torque rods, floating fulcrum brakes and also with the dashpot on the contd:- | ||