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).
Hydraulic damper performance, high-speed road holding, and maintenance issues.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan003 | |
| Date | 2nd December 1930 | |
| -3- Hs{Lord Ernest Hives - Chair}/Sa.1/AL.2.12.30.Contd. hydraulic load of 60 lbs. + 10 to 15 lbs. Hartford load than we do from the standard 60 lbs. hydraulic load. (b) High Speed Road Holding & Steering. Here again we find that the standard damper load + 30 lbs. Hartford gives better results than anything we can do with the hydraulics alone. We do not consider there is any merit in the addition of this small amount of solid friction as such, but rather in the fact that it acts without cushioning on small axle movements which we know is the secret of high speed control. We therefore think that in any design of hydraulic to give variable damping with speed, these factors should be taken into consideration and if it is decided to rely on hydraulic damping only, to stiffen up the levers and shafts etc. to ensure the minimum spring. Even when this is done the working fluid will still act as a very appreciable cushion, as up to the present we know of no way of entirely eliminating the effect of air. We have tried larger replenishing valves but without much result. MAINTENANCE. We dealt with the existing complaints fully in Hs{Lord Ernest Hives - Chair}/Sa.1/MJ.25.10.30. Since then GWH{George W. Hancock - Head Chateauroux}, working from Cricklewood where most of the damper complaints run has observed the following - (1) Mysterious Knocks on the 20 HP. He found that by reducing the travel of the ball over the air vent to .004 he could cure the dampers that were knocking without any other obvious defect such as slack links. We were somewhat doubtful if the movement of this ball alone could account for the noise and therefore took indicator diagrams of the damper with this modification. The result is shown in Fig.4 and proves that restricting the ball valve in this way reduces the damper efficiency by 50% and the pressure rise therein from 230 lbs/sq.in. to 108 lbs/sq.in.under which conditions we should expect the damper to be silent because it is doing less than half the normal amount of work. However, we still believe that this ball valve does make a noise and can be silenced without spoiling the damper, and we are working on it. If we limit the ball travel to .010 the damper is efficient and we think, more silent. (2) Mysterious loss of Oil on Phantom 11 rears. If any foreign matter gets under the replenishing valve the piston pushes the oil in the cylinder through the valve into the atmospheric chamber and out through the Bijur pipe. GWH.{George W. Hancock - Head Chateauroux} actually found a damper that was on a car and doing this. The remedy to prevent loss of oil | ||