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).
Design of Bentley shock absorbers and the combination of hydraulic and dry friction.
| Identifier | ExFiles\Box 87\3\ scan0142 | |
| Date | 1st May 1935 | |
| To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} X242 Ha/Rm.{William Robotham - Chief Engineer}9/KW.1.5.35. Shock Absorbers - Bentley. For some considerable time we have been thinking that we could with advantage alter the general design of our Bentley shock absorbers. This country calls for exceptional suspension conditions and therefore it is not a case where we can follow American practice. We think that we require a shock absorber which combines hydraulic characteristics with the dry friction. That is, for ordinary riding we do not know of any dry friction which is sufficiently consistent to be permissible, but for the controlled part of the damping, dry friction seems to be essential. Last year we had a proof of this with the T.T. Bentley car. We could not get it to sit down on the road to perfection without the addition of Hartfords, no matter how much hydraulic load we had on the dampers. The best results were obtained finally with quite a medium hydraulic setting and quite a light friction load. We have had another demonstration of the extreme value of the small amount of dry friction on 5-B-IV. Here we have reduced the number of leaves in the springs in order to save weight, and Hancock tells us that the whole characteristics of the car have been altered. The amount of internal friction in one of our lubricated leaf springs is so small that it is difficult to measure. Therefore at present we are carrying about 30 lbs. more weight than we need to give us this small amount of additional friction, which does not seem reasonable. The De Ram shock absorber being developed on the Continent shows some of the possibilities of a constant friction shock absorber. As the hydraulic Autolock necessitates the re-design of the damper, we think it is worth while considering this friction characteristic at the same time. | ||