Letter discussing modifications to hydraulic dampers to eliminate knocking sounds during testing.
| Identifier | ExFiles\Box 11\2\ 02-page172 | |
| Date | 8th April 1929 | |
| x7941 Expl: Dept: Messrs. Rolls-Royce Ltd., Derby Angleterre. Hs {Lord Ernest Hives - Chair} /Rm {William Robotham - Chief Engineer} 2/LG8.4.29. Hotel de France, Chateauroux(French test region), Indre, France. x235 Mr. Hancock from Hs {Lord Ernest Hives - Chair} /Rn. {Mr Robinson} HYDRAULIC DAMPERS. We were very interested in your report on the effect of drilling holes in the high pressure valve of the rear dampers. We note that you say that with an .032 hole in the high pressure valve there are no knocks. Are we to assume that the dampers are noisy without any hole drilled in the valves? If so, we should like to know how bad the knocks are. If they can be heard without difficulty in the car we will send out some fresh links for you to try. Mr. Royce has expressed a wish that dampers should be tried with an upward or low pressure loading of 50 lbs. and a downward or high pressure loading of 100 lbs. with the dynamic restrictions removed. The dynamic restrictions are a series of washers arranged with distance pieces to form a tortuous passage through which the oil has to flow on its way to the valves on both the upwards and downward stroke of the axle. When the axle moves slowly, the resistance of these restrictions is small, at high speeds or over a humped back bridge, however, the damper load is increased considerably by this obstruction to the oil flow. contd :- | ||
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).