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).
Experiments detailing the characteristics of wet brake judders on a judder rig.
| Identifier | ExFiles\Box 84\2\ scan0307 | |
| Date | 25th February 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Hs{Lord Ernest Hives - Chair}/AFM.{Anthony F. Martindale} +106 HS{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}20/KW.25.2.35. Wet Brake Judder. The following is a report on the experiments carried out up to date on wet brake judders on the judder rig. The judder is a torsional vibration of the carrier plate, etc., on the axle, with a frequency of approx. 100 cycles/sec. about the stub axle as centre, and has the following characteristics :- (1) If the brakes are applied with the wheel rotating at, say, 20 m.p.h. and it is allowed to come to rest, the judder will commence at a certain speed and continue down to zero speed, the speed at which it commences increasing with increase of brake load. (2) If the wheel is accelerated from rest with the brakes on, the judder commences immediately but dies out at a certain speed, the speed at which it dies out also increasing with the brake load. (3) For the same brake load the speed at which it dies out is higher than the speed at which it commences. (4) Either shoe alone will judder, although, in the case of the wrapping shoe alone, it is more violent and the shoe moves relatively to the carrier plate. (5) During a judder with both shoes in use no movement of the shoe operating shaft occurs, the shoes behaving as if welded to the carrier plate. (6) The brake system servo motor, which is neither wrapping nor unwrapping, will judder violently if wet. | ||