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).
Shock damper tests, discussing axle velocity, pressure, and ride comfort on vehicles 12-EX and 14-EX.
| Identifier | ExFiles\Box 16\7\ Scan029 | |
| Date | 16th November 1927 guessed | |
| contd :- -2- cold on compressor oil we used Prices Motorine 'C'. Whilst carrying out these tests we found out, amongst other things, that the valves do not lift for very small and slow ball end movements - graph.l. Graph.ll. shews that the axle (or piston) velocity dictates the maximum pressure more or less independently of the stroke for front axle velocities above 2 ft/sec. Having therefore ascertained that we could use a plain narrow bore passage to produce increase in loading with increase in velocity without loss of# efficiency with oil temp. rise, we arranged a shock damper as indicated in fig.A. A set of these have run 1000 miles on the front and rear of 12-EX without any trouble from the casings. At high speeds the car is comfortable, at low speeds the riding is hardly soft enough. A set have been fitted to the rear only of 14-EX. On this car they do seem a definite improvement for high speed touring and for axle control, preventing dancing. They do not spoil the low speed riding though it is not so soft as with the standard dampers. We attach a report from GWH.{George W. Hancock - Head Chateauroux} who has carried out a number of tests comparing these with the std. dampers. As a result of these tests, therefore, we are of the opinion that the velocity pressure factor of the present dampers might be increased somewhat with advantage, though for our standard 40/50 we think we have gone too far if we put them on front and rear, even on the rear only the velocity factor is now rather too high. The main difficulty is that when an axle drops suddenly into a pot-hole its velocity is contd :- | ||