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).
Investigations into hydraulic damper knocks, comparing horizontal and vertical types for future design.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan084 | |
| Date | 3rd January 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. SG.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. Da.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. Hy.{Tom Haldenby - Plant Engineer} ORIGINAL Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/MK.3.1.31. X7520 X5520. HYDRAULIC DAMPERS. We have been taking various indicator diagrams of the hydraulic shock absorbers. Those of horizontal type of damper are not of very great interest in view of the fact that it has been decided to adopt the vertical type for future design. However as a matter of interest we send you reproductions of the diagrams. We appear to have learnt the following - P.II. & 20 HP. HEARS. Knocks. (1). The air vent ball has little if any responsibility for the troublesome knock which occurs when it is difficult to detect any wear. We took a typical 20 HP. example on a customer's car and fitted a rubber faced spring loaded valve over the air vent in place of the ball. The knock persisted after the alteration. The rubber face could not possibly have made the noise. (2) We tried various ball valve lifts but until we reduced the lift to the point where our diagrams shew a reduction in damper efficiency there was no diminution in knock. (3) We set the ball movement to standard and the damper knocked. We then changed the links only and the knock vanished. This establishes the fact that in this typical case the knock was due to the end on load reversal on the links (what we have always thought) and could be eliminated either by fitting links without slack or by reducing the load reversal. Diagrams we attach (Sheet I. Col.2.) shew that we can remove the air vent ball altogether without altering the shock absorber efficiency appreciably, and further tests will be made on dampers in service using this to see if in any case the ball itself is responsible for the knock. DRILLED VALVES. The diagrams show that over small movements an .032 hole in the B.V. valve actually increases the damper efficiency slightly on all dampers. Over larger movements this hole reduces the contd. | ||