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).
Extract from a letter concerning an investigation into defective jack rams and subsequent remedial actions.
| Identifier | ExFiles\Box 139\1\ scan0234 | |
| Date | 17th August 1936 | |
| Extract from letter from DONALD SESSIONS & COMPANY LTD "This matter has now been very fully investigated by myself and a set of jack rams were fitted to a chassis on Friday last which performed satisfactorily after a number of tests had been carried out with a view to producing any latent defects. "Naturally I am very upset that goods have been delivered to you which have been found defective after they have been fitted to the car, but the trouble has been mainly caused by the fact that our testing arrangement at the works, although apparently more severe than the test produced by the car itself, was found not to produce exactly the same effect; the jack rams which have been passed off our test as being one hundred percent slightly leaked when tested on the car. To overcome this difficulty we have altered our testing rig which now produces a very much worse condition on the rams than that of the car and I feel confident that any jack ram which passes through our new test will not give trouble on the car. "With regard to one of our jack rams failing on chassis No. 3-AZ-44 at Messrs. Abbotts, Bromley, Kent, I have now had an opportunity of closely examining this jack ram and although difficult to prove, it would appear that this when partially extended had been run into some obstruction which distorted the retaining collar sufficiently to enable the pressure of the fluid to force this collar away from its threads. I understand also, from your works, that a high pressure pump was being used in connection with this set and as you probably know these pumps are capable of producing enormous pressures on the whole of the system; a difficulty which is now remedied by supplying a lower efficiency pump. "All jack rams delivered to you after last Friday will be marked with the letter 'A' on the top caps. Any other type of rams which you may have in stock might be considered to be under suspicion until they are tested on the car. Needless to say I have asked the works to push forward as quickly as possible with replacements of 'A' type jacks. | ||