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).
Issues with shock dampers and proposing improvements for ride quality.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan059 | |
| Date | 4th April 1929 | |
| HS.{Lord Ernest Hives - Chair} DA.{Bernard Day - Chassis Design} ) FROM R.{Sir Henry Royce} BY.{R.W. Bailey - Chief Engineer} OX. ) (At Le CanadelHenry Royce's French residence.) Copy to SG.{Arthur F. Sidgreaves - MD} WCR. Mr. CLAREMONT ORIGINAL REC'D AT WW. 8.4.29. X235 X7420 X5570 X7520 X7830 X5420 SHOCK DAMPERS. I have definitely condemned two things - (1) The leak past the valves. (2) The dynamic passage. The knock will occur if the damper is doing its duty unless the joints are free from slack. Should it be found impossible to keep all joints and bearings close we must attack the problem another way (than making a leak), thus - (1) Opposing springs on at least one ball. (2) The valve in the piston can be, as I once suggested, of the piston type with opposing springs. These ideas give strokes with rounded ends and only very slightly reduce the effectiveness of the dampers. It will be understood that we have to make a slight leak to vacuate the air but even this must not be too large or we shall get a vacuum, so that one valve in the piston, and only one air vent, is the better type. The second point is on the same lines - viz: we need the damper to be equally effective at slow and fast vibrations. As the car travels along the road the axles vibrate at a relatively high period between the road and the sprung car; we do not wish to stop it following the road. But also the body sways about in space at a slow periodicity: this is what we wish to damp, but can only do so by attaching it to the vibrating axles. So that we want the axles that pass a ridge without affecting the body i.e. a quick rise and fall, but owing to the impossibility of preventing the body feeling the ridge somewhat we wish to damp the slow over-run movement of the body with the maximum effectiveness. One thing we should like and that is the larger movements should be more greatly damped than the short ones, but not the quick ones greater than the slow ones. Also the up movement of the axle should have less resistance than the down movement, and finally the ends should be rounded, and the action always the same, hot, cold, worn, or unworn. All this can be done more easily with hydraulic, than by solid friction dampers. We lead the world with this most important part of a car's equipment. Others are not on the scent, and after us. We shall throw away our advantages, and be beaten, if we make mistakes and do nothing to cure them quickly. At the moment we are finding out if we can make the 20HP dampers more effective (like the last two SS{S. Smith}' before we plugged valve leak). The body tumbles about like a mass of many tons, and only very low speeds are possible on this especially bad section of road. I think road springs are too flexible also. The body is a rather heavy Hooper, with that wretched signal window robbing elbow room. R.{Sir Henry Royce} | ||