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).
Test report on the performance of various spring and valve configurations for a damper assembly.
| Identifier | ExFiles\Box 182\M19\ img084 | |
| Date | 2nd June 1931 guessed | |
| - 4 - Another spring giving 8 lb. initial load, and 200 lb/in. capable of being fitted with the sylphon was tried. The most satisfactory results so far obtained were with this 200 lb/in. in conjunction with a masked standard valve having a .025" dia. hole in the H.P. valve, both H.P. and L.P diagrams giving even pressures through-out the 4" stroke. In addition, the damper was quiet, at least, the valve "groan" ceased. The scheme for this damper allows two alternative piston retaining springs, having initial loads of 30 & 50 lb. The D.O. reported that it was impossible to put a spring of even 30 lb. in the space available, and the spring issued by them gave 23 lb. initial load. This spring was far too, light assuming a suction of 14 lb/sq.in. on the piston - the inertia forces reckoned on 4" stroke, 150 RPM. were very small in comparison - and by fitting an extra spring inside the standard spring we were able to obtain a retaining load of 50 lb. This however, with-out the drilled masked valve was noisy and even reducing the piston spring loads to 12 lb. did not seem to have any effect for better or for worse. In accordance with Da{Bernard Day - Chassis Design}2/M19.5.31. a valve was reduced in dia. on the H.P. section thus increasing the L.P. area decreasing the H.P. searing, this had little or no effect. Also in accordance with these instructions, the L.P. passage was chambered out round the valve - Hs.{Lord Ernest Hives - Chair} 354/5 - without success. A hole was also drilled through to the spring chamber, as directed; this also was unsuccessful. The question is asked in this memo - "Does the oil emulsify more or less than standard"? With this damper it is impossible to see the oil when the damper is operating, and the only way in which we could obtain an answer to this query was to remove as quickly as possible the sylphon tube and cover, after running the damper for a reasonable period. From this test it would appear that the oil does not emulsify as much as standard, there being little evidence of air bubbles in the sylphon chamber when the cover was removed. A test was taken with two ball-valve air vents in each piston, first with a standard valve, not drilled, and also with a standard masked valve drilled .025". The diagrams obtained were practically identical, but the standard valve was noisy and the masked valve quiet. | ||