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).
Typed letter from F. H. Royce discussing the performance and design of shock dampers, comparing their own with the Lovejoy type.
| Identifier | ExFiles\Box 16\4\ Scan223 | |
| Date | 2nd December 1930 guessed | |
| (3) But our present dampers should not be unsatisfactory. I have only experienced two troubles - (1) slack developed in the external links, .006" being sufficient to be heard or felt in the rear. This Lovejoy's may have avoided with their rubber or wooden bushed connecting links, (2) loss of oil through central oiling scheme being unwisely connected, and allowed the shock dampers to drain most of their oil away. Internal knocks have been reported (hence our improvements in design) but I think perhaps for your work - (a) the relief valves are set too high, (b) the rear levers are unnecessarily long, (c) the air vent is too large, and (d) the ball valves would be better if the permissible lift was less. Hydraulic shock dampers of the double acting relief valves type (which we originated) and pressure feed from side to side, are the only ones likely to give permanent satisfaction. It may interest you to know that we attempted this type of shock damper in exactly the same form as at present before 1910., but were put on one side because shock dampers were only thought advisable on very fast cars. When we took this subject up again we patented the scheme of forcing the oil from one side of the piston to the other, instead of into the relief chamber, as in the single acting Lovejoy. We now ask this apparatus to do more work than originally estimated, and it has also been fitted up with longer levers, making its duty very heavy, and it fits very exacting, and I believe we are suffering from this practice which has gradually come upon us by the increasing requirements brought about by the higher speeds, and balloon tyres. I have examined the drawings of the Lovejoy double acting type dampers, together with our designer upon this part of our work. We consider it a cheap edition of our own; it contains no features that ours has not. It has no filter or vent to expel the air, and the mechanism should not be less free from knocks, while for wear and repairs the design seems bad. Yours sincerely * This or these have been added in later models. (Sgd) F.{Mr Friese} H.{Arthur M. Hanbury - Head Complaints} Royce. | ||