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).
Potential modifications to the 40/50 front wheel brake servo to eliminate snatching and chanking.
| Identifier | WestWitteringFiles\K\December1923\ Scan23 | |
| Date | 15th December 1923 | |
| R.R. 235A (100 T) (S.H. 159 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 TO HS.{Lord Ernest Hives - Chair} FROM DA.{Bernard Day - Chassis Design} ORIGINAL DA{Bernard Day - Chassis Design}3/M15.12.23. 40/50. FRONT WHEEL BRAKES. SERVO. X9940 We think that the pull off spring on the servo operating mechanism is quite possibly in the wrong place. Could you try an experiment in which there was a spring or springs on the anchor plate of the servo which held the shoes from engaging with the drum until a certain pressure had been reached. This pressure would be that required to operate the pull off springs on the back brakes and take up all the clearance. You would find this pressure rather a heavy proportion of the total force required to operate the servo, but for the purposes of experiment the force of the pull off springs could be reduced. What we expect would happen in this case would be that you would rotate the anchor plate and take up all or nearly all the clearances on the back brakes before the servo closes down on to the drum, and perhaps eliminate that objectionable snatching you have complained of. We also want to increase the windoff on this servo motor as much as possible by increasing the slope of the operating rod. We do not think you can rotate the servo left handedly very far, but we think you might lift the outer end of the operating rod by raising the 3" lever on the bell crank. The limit will be when this leverage fouls the cross member but it would not matter if the rod sloped a little in the plan view in order to clear the cross member. This additional windoff in conjunction with the spring in the new position seems to us to offer great possibilities of stopping the chanking. DA.{Bernard Day - Chassis Design} | ||