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).
Design principles and issues of shock dampers, such as leaks and knocking.
| Identifier | ExFiles\Box 16\4\ Scan070 | |
| Date | 1st April 1929 | |
| Hs.{Lord Ernest Hives - Chair} DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} OY. from R.{Sir Henry Royce} c. to AG. Wor.{Arthur Wormald - General Works Manager} c. to Mr. Claremont. 47520 R1/MA.4.29. X.235 X.5520 X.7520 X.7420 X.7830 X.5420 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 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 overrun movement of the body with the maximum effectiveness. One thing we should like and that is the larger movements should be more greatly dampened 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 the car's equipment. Others are hot on the scent, contd :- | ||