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).
Report discussing oil viscosity in hydraulic dampers and performance tests conducted on the 7-EX car.
| Identifier | WestWitteringFiles\Q\December1926-January1927\ 117 | |
| Date | 27th January 1927 guessed | |
| contd :- ROLLS-ROYCE LTD -2- We also give a viscosity curve of the oil used at present in the hydraulic dampers. Tests on the Condor pump box shewed us that the back pressure occasioned by forcing liquid through an orifice is approximately proportional to the redwood viscosity of the liquid. Therefore it is apparent that if the working conditions of the damper vary between 40°F and 90°F, the back pressure occasioned by any orifice will be about six times as great at the lower temp. as the higher temperature. We have taken a normal atmospheric temperature and arranged the leak so that the valve will just lift for the smallest 'joggle' but any slower movement will force the oil through the leak only. 7-EX car which is at Le CanadelHenry Royce's French residence is arranged to take a hydraulic damper. It is proposed to bring one out on EAC-V11 so that it can be tried in comparison with the friction in the cross steering tube. To ascertain size of bye pass required so that the full spring load of the valve shall be available to damp joggle at 40 m.p.h. but any slower movement shall have a lower max load due to bye pass - Frequency of joggle in step with road wheels 6/7/sec Amplitude of joggle ..................... 4° Angular movement steering lever............ 4° damper lever ............ 5.8° Max: vel: lever end - vibration S.H.M. .... 12"/sec. Av: " " " " " .... 7.6"/sec. Taking average vel: as that effective for damping purposes ... Linear velocity of piston ............... 1.64"/sec. Oil displaced/min. ...................... 4.24 pts. contd :- | ||