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).
On testing shock absorber valve springs, noting issues with supplied parts and suggesting new specifications.
| Identifier | ExFiles\Box 16\4\ Scan100 | |
| Date | 1st June 1929 | |
| x7520 To BY.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/RmL/LG22. 6. 29. SHOCK ABSORBER SPRINGS. x235 With reference to the difficulty in working to the limits we specify on the shock absorber valve springs. We did not make this recommendation without testing a number of springs. We took 20 springs as supplied by the makers. These springs were not made with any special care as the desirability of the minimum variation from spring to spring was not appreciated when they were ordered. We found that a number were too short. These were definitely rejected as we decided that the free length of the spring should be correct. One or two of the springs were more than +.030 on the length and these were also rejected. The remainder were ground down to size and tested out in a damper. We attach the results which indicate that if the springs are produced by the makers to the specified free length with a limit of not more than +20 and ground to +3 on the free length in these Works, there should be no difficulty in getting the shock absorber poundage within the specified limits. We suggest that the only method of testing these springs for poundage should be in a model shock absorber as the facilities in the Stores for testing the poundage of small springs at high rating are not very good. We feel quite confident that if the free length of the spring is fixed, there will be very little difficulty in getting the right poundage on the shock absorber at the set up in question and that the number of springs to be rejected will be low. You will observe that we have taken considerable trouble over this point and we should therefore like you to find out whether our results can be reproduced in the Works. If any difficulty is encountered, we shall be only too pleased to take the matter up. Incidentally it appears that the recommended poundage will be: 60 lbs. up. and 60 lbs. down on the front. 60 lbs. up and 80 lbs. down on the rear. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||