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).
Letter to The Armstrong Patents Co. Ltd. regarding the testing of shock damper components and a request for new parts with modified specifications.
| Identifier | ExFiles\Box 152\2\ scan0219 | |
| Date | 6th July 1940 | |
| 1293 6.7.40. Rm{William Robotham - Chief Engineer}/Clm.{D. D. Clapham}1/JMS. Messrs. The Armstrong Patents Co. Ltd., Eastgate, Beverley, E.{Mr Elliott - Chief Engineer} Yorks. For the attention of Mr. Hogg. Dear Sirs, In March last you supplied us with a pair of zero clearance pistons and an .004" interference sealing piece for a D.A.S.10 shock damper. We regret we have not informed you previously of the results of our tests on these pieces. We found that they together reduced the variation of leak with increase in temperature until it became negligible. The pistons could be assembled at room temperature without much trouble, but the case had to be heated to about 60 deg.C. before the sealing piece could be screwed in. We are now proposing to use one of your large dampers (D.A.S.12 size) experimentally on another job altogether, and we are up against a similar trouble. We want to reduce the natural leak at normal temperatures to as near zero as possible, and we should like to do it in the same manner as on the D.A.S.10 damper. The actual damper we want to use has the hand control gear as shown on drawing No.469-Z, except that we have removed the valve spring and inserted a rigid distance piece so that the damper is either free or locked solid, according to the position of the hand lever. This is why we want to reduce the leak to the absolute minimum. As the damper will not get hot it will not need so much interference on the sealing piece and we would suggest .002". We should be much obliged if you would send us as soon as possible an .002" interference sealing piece and a pair of zero clearance pistons for the hand controlled type D.A.S.12 size damper. It would assist us if the pistons were attached to a rocking lever to save removing and replacing link pins. Yours faithfully, | ||