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).
Investigation into a gear-type shock damper control unit to replace the governor unit on the Bentley and Wraith.
| Identifier | ExFiles\Box 151\2\ scan0382 | |
| Date | 6th February 1939 guessed | |
| GEAR TYPE SHOCK DAMPER CONTROL UNIT INVESTIGATION. The gear type control unit used on the Bentley and replacing the governor unit on the Wraith has no pressure-velocity effect. It was desired to investigate the possibilites of introducing a certain amount of pressure-velocity effect and enough viscosity control to maintain substantially the same pressure at any one speed independent of temperature. The pressures that it was considered desirable to obtain were:- 10 m.p.h. 80 m.p.h. MAX. 10 lbs/sq.in. 20 lbs/sq.in. MIN. 0 lbs/sq.in. 10 lbs/sq.in. For the first tests a Bentley shock damper valve was used in an external seat but later valves were made to fit in the pump in place of the ball valve, and all graphs refer to the latter type of valve. Pressure-Velocity Effect. Curves were taken at 20°C and 100°C for the hard and soft positions using a valve having a 20° taper and a suitable spring. These curves are shown Sheet 1. It will be seen from the curves that if a constant pressure change is to be obtained for a given speed change it will be necessary to obtain a spring of which the rate varies with temperature, It might, however, be possible to adopt a satisfactory compromise giving the correct pressure differences at the operating temperature. Alternatively this effect could be reduced by adopting a valve with a slightly concave taper: this has the result of increasing the effective spring rate at high valve lifts (i.e. low temperatures for a given pressure) A shaped valve might also be of use if it were desirable for the pressure velocity relation to obey a square law. Pressure temp. characteristics. Sheet II shows the valve lifts necessary to maintain a constant pressure at a constant speed but under varying temperature conditions. It will be seen from these curves that the movement required from the bimetal strip is not proportional to temperature so that it will be necessary to use some form of | ||