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).
High-speed resistance in hydraulic shock dampers and proposing methods for analysis.
| Identifier | WestWitteringFiles\Q\April1927-June1927\ 112 | |
| Date | 9th June 1927 | |
| TO HS.{Lord Ernest Hives - Chair} FROM DA.{Bernard Day - Chassis Design} ORIGINAL DA{Bernard Day - Chassis Design}1/M9.6.27. Y235 HYDRAULIC SHOCK DAMPERS. With reference to HS{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer}1/LG2627., we suggest that the resistance experienced at high speeds, which appears to be independent of the viscosity, is that required to impart kinetic energy to the oil in order to force it through the high pressure valve port. If the fluid were water, and the valve port .1875 in dia. without any length, a pressure of approximately 150 lbs. per sq. in. would be required at 20" per second piston speed. This resistance increases and directly as the square of the speed inversely as the fourth power of the dia. of the aperture and is therefore a very important factor at high speeds. It is of course entirely independent of the viscosity or of any other friction effects. We suggest that it would be of considerable interest to us if you could analyse the different resistances. There is the frictional resistance due to the long passages, right angle bends, restriction due to the valve etc, and there is this kinetic resistance due to imparting velocity to the oil in order to pass through the aperture. It appears to us that it would be possible to dissociate these two so that we might get an idea of their relative importance. One suggestion is to fit a jet of small dia. but short length to one of the passages to the low pressure valve, blocking up the other passage. DA.{Bernard Day - Chassis Design} [Signature] | ||