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).
Increased requirements and challenges of designing effective shock dampers for modern cars.
| Identifier | ExFiles\Box 16\4\ Scan211 | |
| Date | 22th November 1930 | |
| SG.{Arthur F. Sidgreaves - MD} PM.) FROM R.{Sir Henry Royce} C. ) to WOR{Arthur Wormald - General Works Manager} HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} R1/M15.11.30. Sent off 22.11.30. CAR WORK - SHOCK DAMPERS. X.7520. X.5520. X.235. The situation about these is not very well understood. When we first started to fit them the work we had to do was very much less than they are now asked to do. The reason for this is that originally the road springs did a great deal of the damping, and shock dampers were only fitted to add to the friction when the springs were oiled, and as they were never well oiled the duty of the shock dampers was very much less. We then come to a period of much higher speeds, and balloon tyres, all of which materially adds to the requirements of the shock dampers. On our own cars we run with a very large bump clearance at the back axle, and the recoil from the back axle bump is thought to be as much as 10" so that the total stroke of the end of the lever of the rear shock dampers is in the neighbourhood of 15", which has to be provided for in clearance in the shock damper, and to avoid the levers toggling the levers has to be very long. So you will see that the duty of the shock damper is enormously greater than in the old days when most motor cars ran without shock dampers at all. The last straw that has broken the camel's back is that we put the central lubrication to the springs, and the springs are so well lubricated, together with other things to reduce the friction such as plating, and polishing, that the car is positively dangerous unless the shock dampers are effective. All this is added to the duty required of this originally novel apparatus. Most other types have proved to be ineffective, or to have the objection of rendering the car harsh and very irregular in its behaviour. The Houdaille, which depends largely upon viscosity, only seems to escape destruction by losing its oil and becoming ineffective, that is to say, they soon wear badly and leak, then their duty is ended and they are thought to be very satisfactory for slow speeds because they are not doing anything. All the cars examined at the Show with hydraulic shock dampers were found to have very short levers with very stiff road springs, so that had the axles moved as far as ours the result would be disastrous. The buyers of our cars having paid a very high price are highly critical about the slightest imperfection of any part, and should be realised that we are trying to live up to expectations which are nearly impossible, unless the springs are definitely unsuitable for the load. (1) | ||