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).
Preliminary tests of hydraulic shock absorbers, investigating a chattering issue caused by trapped air.
| Identifier | WestWitteringFiles\O\2January1926-March1926\ Scan66 | |
| Date | 1st February 1926 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} ORIGINAL Hs{Lord Ernest Hives - Chair}/Rml/LGS. 2. 26. X235 J8520 R-R HYDRAULIC SHOCK ABSORBERS. We have carried out a number of preliminary tests on the R-R Hydraulic shock absorbers to N. sch. 2085. The main difficulty that we have experienced so far is to exclude air from the shock absorber. The effect of a small quantity of air in the system is rather peculiar. The lost movement occasioned is almost negligible. The trouble is confined to a high frequency chatter of the high pressure valve when the master piston is forcing oil through this valve. The chatter is such that it can be heard from the driving seat in the form of a squark when driving over rough roads. The smallest quantity of air in the system is sufficient to promote this chatter. If the shock absorber is filled normally, the chatter is always present. This is also the case if the cap is removed from over the high pressure valve and the shock absorber filled before this cap is screwed home. The high pressure valve chamber being the uppermost point in the high pressure system, any air bubbles being forced round with the oil, naturally tend to collect there. We know that the chatter is due to air in this chamber because if we carefully exclude air by fitting a small auxiliary plug in the top of the valve dome as in the sketch, and screw the plug home while actually forcing oil out of the orifice, we eliminate the chatter. contd :- | ||