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 shock damper valve 'hat' clearance and its effect on operational quietness.
| Identifier | ExFiles\Box 151\2\ scan0130 | |
| Date | 1st January 1934 | |
| Files Hs {Lord Ernest Hives - Chair} /Ref. LES See me HS {Lord Ernest Hives - Chair} x4698 1.1.34. SHOCK DAMPER VALVE TESTS. Effect of "Hat" Clearance with Regard to Quietness. Valve Assembly F.85641. With the previous type of valve used on production (F.100695) it had been ascertained that with a diametral "hat" clearance of .015", the "squawk", to which the single type of valve is prone, was just faintly audible, and in view of this fact the clearance was standardised at .010" for production purposes. With the introduction of the split valve (F.85641) in conjunction with the governor control, it was hoped that the diametral clearance could be increased, and thus overcome the peculiar "load loss" effect which appeared at this stage of the development of the single valve damper. Also it was anticipated that the increased "hat" clearance would make the ball pin loads more uniformly progressive in relation to the external pressure applied. Consequently, a damper having .030" diametral "hat" clearance, was tested on the variable speed rig. With the damper temperature at approximately 30°C., the "squawk" began to develop when external pressures in excess of 10 lb/sq.in. were used, up to a MEAN AXLE VELOCITY of 0.3 ft/sec., after which valve "knock" was heard. The latter increased in intensity as the speed increased, but it was considered that in this particular respect, the single valve was better than the double valve dampers previously used on production, the sound being slightly muffled. With .020" "hat" clearance the "squawk" began to develop round about 15 lb/sq.in. external pressure, at the same M.A.V. as before, but was not so marked, the valve "knock" also being slightly reduced. Using .010" "hat" clearance, the "squawk" was very faintly audible between 25 and 30 lb/sq.in., and in view of this we consider that this is the maximum clearance which can possibly be allowed for production dampers. Hs {Lord Ernest Hives - Chair} /W.Bell. | ||