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).
Axle jagger issues on Bentley cars, including experimental work and potential solutions.
| Identifier | ExFiles\Box 85\1\ scan0104 | |
| Date | 15th June 1936 | |
| To Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} c. to WOr.{Arthur Wormald - General Works Manager} c. to C. c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Mx.{John H Maddocks - Chief Proving Officer} X2/6 Ha/Rm.{William Robotham - Chief Engineer}1/KW.15.6.36. Axle Jaggers on the Bentley. As we pointed out in Ha/Rm.{William Robotham - Chief Engineer}1/KW.26.3.36, brake jaggers are at the head of the urgency list of our experimental work. Since that date we have had a case where a jagger has occurred on a customer's 4 1/4 litre car - B-180-GA, Chubb. This is a mild reproduction of the phenomenon which occurred when Jack Barclay was driving 4-B-IV. We have done an enormous number of experiments with a view to fundamentally eliminating jaggers, and we have one experimental scheme which so far is completely successful but unfortunately it is not altogether suitable for production. The designed form of this scheme for some reason which we are unable to explain is not effective. In co-operation with the design, however, we are going to get something on C-B-IV before it goes to France which can be put on production if it successfully completes 15,000 miles' running. We have, however, to anticipate that even if the feature we fit to C-B-IV is a complete success, it will be at least 4 months before cars can be begun to be delivered to test with the modified parts. Knowing the complexity of the problem, however, we think there is every prospect that we shall run into some further difficulty which would further delay standardisation. It should be appreciated that the 4 1/4 litre car is likely to be worse for jaggers than the 3 1/2, because it is possible to overheat the brakes more due to the better performance, and an overheated brake is one that will readily jagger. There is one palliative available which we can say definitely reduces the chance of a front axle jagger very considerably; this consists of removing a portion of the lining at the toe of the shoes. The objection to this modification is that it renders the Hancock brake shoes inoperative. It is for this reason that we have hesitated to apply it previously. Even if brake squeaks are increased we think this complaint is preferable to the chance of an accident. For various reasons, however, we do not think that squeaks will be a great deal worse. | ||