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 potential solutions for axle tramping during braking.
| Identifier | ExFiles\Box 84\2\ scan0138 | |
| Date | 12th April 1934 | |
| - 2 - E.1/HP.12.4.34. We should however like some more particulars from Bn.{W.O. Bentley / Mr Barrington} of the circumstances attached to this dying away of the braking effect so that we can more closely identify the trouble. The next point mentioned is:- (2) Axle tramping due to brake application. ---------------------------------------- We are aware that the front axle can be made to tramp when the brakes are applied if the conditions are favourable to this result, but it is not the fault of the brakes. Experience indicates that the car itself must have a predilection to this phenomenon and the road surface must be such as to excite it. When we have experimentally rigged up a car with the idea of making it susceptible for tramping, it has been noticed that a flick of the brakes would often start the axle on the move after the right road speed had been attained when it would not excite itself. We have experienced this phenomenon with other makes of cars but we are of the opinion that it does not happen except on a peculiar stretch of road surface. The right combination of conditions and road surface is likely to be most infrequent. Improvement lies in direction of making the chassis itself less susceptible to tramping. Assuming the wheels and brake drums are in balance the make of tyre also entered into the question, and we should like to know what Bn.{W.O. Bentley / Mr Barrington} is running. We have always understood that India tyres have less inherent damping than Dunlop, for example. Where we are trying to make some definite move affecting this point is in the application of controlled wheel damping. We have designs ready now for the application of this to the Bentley for the forthcoming 10,000 miles test and we suggest rigging these up forthwith on a car for preliminary trial as to their general effect on the stability of the front axle. It will be the driver's own fault if he is not using more maximum damping when braking at high speed. Finally we come to the question of | ||