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).
Shock absorber failure, oil viscosity tests, and performance theories.
| Identifier | ExFiles\Box 28\1\ Scan121 | |
| Date | 26th March 1928 guessed | |
| contd :- -2- We do not think however that it can do any harm to increase the dimensions of the refilling passages and are therefore conducting some tests on these lines. We are completely mystified by the breakage of your rocking shaft lever. We must have run the shock absorbers some millions of miles on our own and customers cars since they emerged from the experimental stage and we have not had a single case of this type of failure. As a matter of fact we particularly tested the shock absorbers with Motorine 'C' at 10°C to get the effect of zero weatherpon the compressor oil which we used as standard in the shock absorbers, and our pressure gauges did not ax shew a rise of more than 15 to 20% on the high pressure side. We have never been able to detect any harsh riding in cold weather with the compressor oil we are using. Attached is a comparative curve of the ex viscosity of a number of oils we have tried. Our explanation for the fact that we did not get a large increase in pressure with thick oil is that most of the loss in the passages is K.E. loss and not true viscosity loss. We have recently done a number of experiments which shew us that we can make a K.E. loss almost independent of the oil viscosity for quite a wide range. We do believe that the shock absorber may perhaps ride virtually idle for very rapid small amplitude vibrations but on the whole consider this is an advantage as it makes it possible for us to obtain reasonable Boulevard riding and yet use pressure which will control the car at high speeds on a bad road. contd :- | ||