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).
Leverage, adjustments, and performance of rear Girling brakes.
| Identifier | ExFiles\Box 83\1\ scan0400 | |
| Date | 11th March 1937 | |
| 2000. To Rm{William Robotham - Chief Engineer}/GWH{George W. Hancock - Head Chateauroux}/IMW.{Ivan M. Waller - Head of Chateauroux} from Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} c. c. to Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}9/AP.11.3.37. 6.B.1V. REAR GIRLING BRAKES. In reply to your memo Rm{William Robotham - Chief Engineer}/GWH{George W. Hancock - Head Chateauroux}/IMW.{Ivan M. Waller - Head of Chateauroux}7/JAB. The leverage on the hand brake to rear is approx. 92.7. This is as good as standard and Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} in England said he thought it as powerful as standard. The leverage of foot pedal to rear direct is 27.7. The movement of the hand brake lever is approx. 12 1/2". The pedal movement is probably not more than 3 1/2". That is to say the hand brake can move the shoe tip .135", the pedal .126", or in other words, the pedal should be on the boards before the H.B. becomes inoperative. Now if you shorten the 4" lever to 2 1/2" (if this is what you have done) you have made certain that the hand brake becomes inoperative before the pedal is on the boards, and if you were to lose a pin from the pedal mechanism when the rear brakes had worn more than 7 clicks you would have no brakes left on the car. This is a bad thing. We rather gather from your various reports that we have succeeded in building a fairly sponge free brake system. We should make full use of this by widening the rear shoes ( as we can) and increasing the rear brake leverage by say 50% on both hand and foot brakes, and reducing the servo output to rear. This will give you the additional sponge you require on pedal and H.B. lever, and give you more powerful foot brake in the event of servo failure. You will not have to adjust the brakes more often. If you keep the rear brakes well adjusted up there is no reason why you should not make the alteration you suggest, as we do not want to standardise any part of this brake system. May we advise you to examine the e xterior of your rear brake drums quite frequently.? Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} | ||