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 solutions for 'servo jaggers' in braking systems.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan253 | |
| Date | 7th December 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. ORIGINAL Expl. No. REF: Hs{Lord Ernest Hives - Chair}2/LG7.12.25. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJV BJ. c. to RGV E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} SERVO JAGGERS. +8370 T5370 We find that giving the servo more work to do, by increasing the strength of the pull off springs on the front brakes, is not a cure for servo jaggers. The cure which we always find effective is introducing flexibility in the operation of the servo. The 20 HP. car which is at WW, is fitted up with this arrangement. We have also tried it on 8-EX car in France and on several cars at the Works which have been complained of for servo jaggers: In every case it has definitely overcome the trouble. We consider that if a proper scheme was got out to allow of .020" flexibility which would mean a loss of pedal movement of approx. .170", this should definitely overcome this fault. The factors which influence servo jaggers are :- (1) Condition of the friction surface. We can always overcome jaggers for a short time by scraping the friction surfaces. The material used on the surface is one without any sticky dressing. (2) The amount of slack in the servo drive also influences it. A servo with a lot of slack in the drive will jagger more readily than one with little slack. Hs.{Lord Ernest Hives - Chair} | ||