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).
Car suspension, focusing on the design and damping of cushions and squabs to improve ride comfort.
| Identifier | ExFiles\Box 55\4\ Scan400 | |
| Date | 4th July 1930 guessed | |
| - 2 - When the front dampers have been set to keep the nose of the car steady over uneven roads, it may be considered that very little more can be done with the design and material at our disposal. Matchboxing scuttles, jellying radiators and bad body rattles have separate and collective tendencies to promote an erroneous opinion of harsh springing and if remedied will help the customer to form a more favourable impression of the car generally. Cushions and Squabs. The design of cushions and back squabs is of considerable importance. Of ten complaints, nine boil down to the "coup de racquet" type. My experience is that customers are unable to describe in a few words the causes of their discomfort, they nearly all say "I am thrown about inside the car". The squab should in my opinion be of uniform deflection construction which offers an equal resistance over the greater part of its surface. The resistance should be much less than is usual because in a sitting posture a passenger's shoulders impose very little pressure. Reaction should be damped and as sluggish as it is possible to make it. A good practical test is that with the fingers of one hand outstretched, one should be able to easily deflect the squab and feel no reaction and little resilience. I find most coachbuilders concentrate on giving support at the waistline whereas comfort for the shoulderblades is in my opinion the chief consideration, one often finds no padding at all at the top of the squab. If the squab reaction is not considerably damped, the passenger is jerked forward after the depression brought about the shock. One gets a tennis racquet effect hence the expression "coup de racquet". To prove this if two people will ride in a car which has springy squabs and one of them sits forward clear of the back while the other takes up a natural position, the demonstration will be convincing. Much of the above argument applies to the main seat cushion as regards damping. My conclusions are that it is of little use wasting time and money if the cushions and squabs are not satisfactory. That once suitable road springs on the lines indicated above are fitted it is a question of damping only. It is useless in my opinion to try and make a Shock damper offset faulty squabs and cushions or incorrect weights of springs and this is more important with weak springs. The tendency is for some of us to expect the shock absorber to carry load instead of using it as a friction or resistance machine to damp movement. I have tried cars the springs of which have been too weak and the Shock dampers have been set up to counteract crashing the result is that an undue proportion of the Shock is taken by the damper and the customer complains of vibration and hard riding. .../... | ||