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).
Road and bench tests of Delco adjustable hydraulic dampers, detailing the adjustment mechanism and its effects.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan134 | |
| Date | 14th January 1931 | |
| ORIGINAL To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Da.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KT.14.1.31. DELCO ADJUSTABLE HYDRAULICS. X832. We have now received the complete set of these dampers that Hs.{Lord Ernest Hives - Chair} obtained in America and subjected them to both road and bench tests. These dampers are some of the first to incorporate an adjustment that can be easily altered by the car owner without any tools. Adjustment. This consists of a variable leak between the high and low pressure valve passages and is really equivalent to an adjustable size of drilled hole in one of our R.R. valves. The valves themselves have no groove in the stem, the necessary leak being by adjustment. The attached sketch indicates the great simplicity by which this adjustment is obtained. The gland for the adjusting screw is prevented from working under pressure by means of a relief passage which is drilled from the bottom of the screw thread to the centre of the cylinder bore i.e. the atmospheric chamber. There are four markings to indicate degrees of leak and a stop at each extreme so that the leak cannot be altered above or below a certain amount. Whilst on test we have so far observed no tendency for the gland on the adjusting screw to leak. Effect of adjustment. (1) Long Strokes Sheet 2. Bump. The leak makes no appreciable difference to the low pressure loading. Rebound. The action of the leak is fairly positive, the maximum pressure attained varying about 100% at normal axle movements between Nos. 1 & 4 leaks. (2) Short Strokes Sheet 3. Bump. The leak as will be seen, cannot be said to have very desirable characteristics, as whilst it reduces the total damping it has little effect on the maximum pressure. Probably in endeavouring to alter the High Pressure Characteristic the Low Pressure has had more or less to take its chance with the observed result. Rebound. The leak here definitely softens the max. pressure but not so much as over long strokes. Thus the pressure increases about 25% between No. 4 & No. 1 leak instead of 100% as on the long strokes. | ||