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).
Driver-controlled versus automatic shock dampers, proposing a speed-dependent system.
| Identifier | ExFiles\Box 178\3\ img094 | |
| Date | 7th March 1932 | |
| HS.{Lord Ernest Hives - Chair} E.{Mr Elliott - Chief Engineer} FROM R.{Sir Henry Royce} BY DA{Bernard Day - Chassis Design}/FDY. (At Le CanadelHenry Royce's French residence.) Sent from WW. 7.3.32. C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} BC. R5/M5.3.32. C. to PN.{Mr Northey} FR. K7520. x5520. SHOCK DAMPERS - DRIVER CONTROL. Though evidence suggests that this would be desirable we must not imagine it would cure all our troubles, because - (1) we should still have to adjust the flexibility of the road springs to the weight of the car, and to the customer's wishes, general loading of the car, and speed of driving, (2) there would be cars with passengers and weight badly disposed, passengers over back axle, etc. No. (2) are I believe still being made and cannot be avoided until we make some drastic moves in design. I repeat, fit anything you like for experimental and special customers' use, but as far as my personal work and responsibility is concerned the following appeals to me: (I) I think better results yet can be obtained without any control, as shewn by past work, and the car here. (II) Because controls I have seen cannot be worked frequently and easily enough for changes of speed brought about by short, fast, stretches of road mixed with slow pieces. (III) Except with specially careful and enthusiastic drivers such adjustments are either not made, or are generally in the wrong place, or they may get out of order and do more harm than good. In short, they are still another gadget for the driver to continuously work, not set an adjustment. I long ago saw the desirability of changing the damping with the road speed - (a) automatically, which sounds quite possible by the hydraulic control (oil pressure) that we are considering, in the following way: a small gear pump is driven by the transmission following the speed of the car. On the same spindle is a small centrifugal governor (in all about the size of a speedometer or lubricator.) This closes the relief valve and causes the pressure to rise, and the dampers to increase in loading, independently of the viscosity of the oil. [GRAPH] Vertical axis shows increasing damping, horizontal axis shows increasing speed. A horizontal line is labelled "Constant damping.". An upward curve is labelled "Variable with speed.". The horizontal axis is marked "45." and "90 MPH.". [/GRAPH] (1) | ||