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).
Potential causes and solutions for oil loss in hydraulic shock dampers, including a diagram.
| Identifier | ExFiles\Box 68\2\ scan0140 | |
| Date | 5th March 1926 | |
| To DA.{Bernard Day - Chassis Design} Hs.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} } FROM R.{Sir Henry Royce} c. to CJ. BJ. c. to E.{Mr Elliott - Chief Engineer} RG.{Mr Rowledge} 18520 RL/M5.3.26. HYDRAULIC SHOCK DAMPERS. X.235 X.8520 Hs{Lord Ernest Hives - Chair}'s memo. received re. oil loss. I wired Derby :- "DAMPERS MAY REQUIRE BREATHER OR MORE OIL TIGHT PISTONS OR CAVITY WITH RETURN PASSAGE BETWEEN BEARING AND GLAND". (1) If there is no other ventilation except gland then any change of pressure inside may force oil through gland. Change of pressure could be caused by change of temperature or by compressing any air behind either piston. Breather would keep at same pressure inside as outside so there would be no loss of oil from this cause. (2) Too large a percentage of oil might pass pistons instead of going past relief valve. This would suggest better fitting high pressure piston, by longer fit and grooves, or by piston ring pinned at bottom. (3) Oil may be squeezed along bearing by ordinary bearing pressure and out through the gland. The remedy for this would be an annular cavity just inside gland. This cavity would have drain passage back to reservoir, and might have a collar so as to be still more oil retaining. Such a collar could best be a split ring pushed on after gland and packing. [Diagram of a piston gland assembly] Note the plate behind gland packing. This is probably the thing that is wanted. Possibly we could make a simpler and better apparatus by doing away with the top valve of long passage and arranging both high and low pressure in piston. Anyway we might try the oil, and of a form to keep themselves free from air, (cancel the low pressure restriction vent and ball), and try if the natural piston leak will get rid of the air. The double valve is the simplest, and could be tried with the other features and passages blocked up. The suction would be somewhat thus:- SEE ORIGINAL FOR SKETCH. contd :- | ||