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).
Description of the design features and operation of the Bentley & Draper shock damper.
| Identifier | ExFiles\Box 178\4\ img010 | |
| Date | 5th April 1932 guessed | |
| BENTLEY & DRAPER SHOCK DAMPER. The most peculiar feature of this damper is the diameter of the piston, which, being only .875" must generate very high internal pressures for given ball pin loads when compared with the more usual piston of 1.500" to 1.750" diameter employed in dampers suitable for this size of chassis. In consequence the valve springs are exceptionally strong, and of high rating. The valves are also unusual in shape, each being almost an inverted cone with a short stem projecting from the base for spring location, and, contrary to the usual practice, the valve seating extends the full length of valve; liable to make the valve "sticky". The oil after passing through the valves from the cylinders empties directly into the reservoir, and the cylinders must therefore be refilled entirely through the oil replenishing valves situated in the piston. At each end of the piston (which is made from ground bar, with a section cut out of the centre to take the guide block) there is also a small, spring loaded, non return, ball valve, through which apparently, oil is pressure fed to the sliding faces of the piston, and guide block, and possibly to provide a certain amount of air release. Below the main cylinder bore, there is another bore, the two being connected at each end by an oil passage. Two strong springs support between them a very short piston, which is .005" less than the auxiliary cylinder bore. This evidently provides a "fixed" leak, and also lessens the initial shock on the main piston. The intermediate lever which is fixed on to the main shaft by the squared shaft and clamping screw method produces piston motion through an integral overhanging pin at its lower end, which fits into the guide block. The main shaft has no rear bearing, and the main bearing is designed, so that it can be pivoted about one of its securing bolts (which, incidentally is also a frame bolt) to a limited extent, an eccentric adjustment being provided under the lowest of the three securing nuts. By this means the relation between the piston and the ball pin movements can be altered. | ||