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).
Modifications and issues with the Bentley braking system.
| Identifier | ExFiles\Box 83\2\ scan0230 | |
| Date | 10th February 1938 | |
| To. Rm.{William Robotham - Chief Engineer} c/o Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} 2000 CHATEAUROUX 9/ 10.2.38. 6.B.IV. - BENTLEY. BRAKES. Replying to your memo Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}4/JH.4.2.38, the front brake equaliser shaft is now fitted with 1.84" crs. outside levers and a standard production 1.75" crs. front plate lever. Please note that we have now set the plate lever in line with the outside levers, instead of at an angle as shown on the drawings. This arrangement of levers and set up gives a good all round proportion of front to rear braking and is free from thumps which have previously been the chief snag of this system. The length of the front brake ropes is 43.9/16". We have found that the crossmember between the front anchorages of the rear springs is overloaded by the rear brake idler lever. Considerable deflection takes place under heavy braking, which accounts for a little of the sponge, and the lower fixing bolt between the crossmember and the frame has worked loose. To overcome the trouble, we are making up a special idler lever in the form of an inverted T which will give equal leverage for in- and out-put, and relieve the cross- member of the present forward thrust. This will increase the leverage to the rear brakes slightly and it may be necessary to increase the length of the output lever on the rear brake cross shaft to compensate for this. Will you please produce the necessary output lever and also an idler lever to replace our mock up and send them out. We regard this modification as necessary and important. The reason the trouble does not show up so badly on the standard production job, is that only half the rear braking goes through each idler instead of all of it in this system. We will fit the new rear brake rod parts when to hand. The front brakes did work alright when the rod failed, and during the run back to Châteauroux developed squeaks. This was with B.Z. and the tipping shoes set solid. We are also running the M.R.3 with the tipping shoes solid so as to get a true comparison between the two linings. RM{William Robotham - Chief Engineer}/IMW{Ivan M. Waller - Head of Chateauroux} Ivanher Waller. | ||