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).
Knocking shock absorbers on the 20 HP car caused by a faulty non-return replenishing valve.
| Identifier | ExFiles\Box 55\4\ Scan282 | |
| Date | 1st December 1928 | |
| To DA.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to Wor.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} c. to Hm.{Capt. W. Hallam - Head Repairs} MX.{John H Maddocks - Chief Proving Officer} [Handwritten] X235 [Handwritten] Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}5/LG4.12.28. KDM KNOCKING SHOCK ABSORBERS. [Handwritten] X5520 X8520 X235 Whilst investigating noisy shock absorbers on the rear of the 20 HP. car we have come across a sourse of trouble which we have not previously appreciated. In order to obtain a good seating it is usual to tap the ball of the non-return replenishing valve when it is in position. If this is done repeatedly, the ball valve sinks in the aluminium until it is located in a little cylinder instead of on a conical seat. We are not sure that it cannot also get into this condition by hammering when the shock absorber works, if the ball is given too much initial lift. The fact remains that when it is in a cyl. its opening is delayed and also it is liable to stick closed, since its inducement to open in any case is a pressure of less than 15 lbs/sq.in. If it does not open promptly, or sticks closed, the oil which is ejected through the air vent is not replaced. This means that under working conditions, there is lost movement in the shock absorber. The sudden loads caused by this lost movement produce knocks. This trouble is not very easy to detect because the lost movement is not always apparent unless the shock absorber is operated rapidly on a rig. We think this may be the cause of some contd :- | ||