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).
Suspension damping, orifice effects, and the phenomenon of 'boulevard jerk'.
| Identifier | ExFiles\Box 170\2\ img103 | |
| Date | 18th October 1931 guessed | |
| low "dry friction" in the suspension, the lack of damping at the inception of axle movements allows them to build up to greater amplitudes, & shake the car actually more with orifice than without. We do not find that we can dispense with orifice entirely even when we have - a) very light damper loads b) Exceptional spring lubrication. c) Low "build up" in the dampers. - because, without some orifice effect we get "boulevard jerk", which we find to be nothing more than the natural bounce & pitch-frequency (principally pitch) of the car as a whole on its tyres, the tyres being springs of approx 2000 lbs/in & giving frequencies in the neighborhood of 250-300/min. We do find however that orifices between .0005 & .0010 square inch such as we used on the Spfld Rolls, are adequate to get rid of boulevard jerk without detracting from stability. The effect is about like curve A above. Having got so far, the next step is obviously to regulate shocks by varying the spring-load on the valves, which can be quite simply done. | ||