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).
Critique and functional analysis of a damper's venting, filtration, and valve mechanisms.
| Identifier | ExFiles\Box 28\1\ Scan205 | |
| Date | 30th January 1931 | |
| -2- (3) Venting. They allow an appreciable leak past the screw holding the two piston halves together, we have to confirm if this has any effect on the damper performance, it may be an additional vent. (4) Absence of Filter. Apparently they manage to do without a filter by having their replenishing valves as described and masking their main valves (see sketch) so that even if foreign matter collects on the seat the damper only loses a small proportion of its total poundage. The seats of the pressure valves are also of small width (more possible by cast iron) and vertical. (5) Silencing of Valves. The L.P. valve is really a spring controlled leak except for the most violent axle movements, and the leak is controlled by a very weak spring. The valve therefore has little tendency to return to its seat noisily. The H.P. valve on the other hand is controlled by a powerful spring and as the loads can easily reach 800 or 900 lbs/sq.in. on this stroke the valve would undoubtedly be noisy. They appear to have silenced it by having an unbalanced discharge which tends to force the valve against its guide. Certainly there is no noise. The points we have to criticise with this damper are :- (i) The reserve of oil is too small. The loss of little over a tablespoonful impairs its efficiency. (ii) The loads are reversed on its main bearing, they are not on the new damper (R.R). Furthermore they make no provision for getting oil to this bearing which is directly in the case. Presumably the generous dimensions of the bearing make this permissable. (iii) The annular clearance of .007 round the mask of the H.P. valve is too small and is likely to become stuck with grit. FUNCTIONING OF DAMPER. Low Pressure Valve. This is masked, and consists for axle velocities | ||