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).
Observations on competitor hydraulic instruments.
| Identifier | ExFiles\Box 16\4\ Scan189 | |
| Date | 27th September 1930 guessed | |
| OY-2 - 3 - Watson and Gabriel both have new hydraulic instruments. (The new Stewart Warner is announced in the enclosed folder, which may amuse you. I know nothing about it.) We notice on all these instruments:- (1) The bodies are cast iron weighing 6 to 10 lbs. and averaging 3/16" to ¼" thick. They seem to us like "sinkers", but one has to believe that the mass of metal must absorb a lot of noise. (2) The C.I. bore gets a high shine on it like an engine cylinder. Pistons are sometimes bronze and generally cast iron. There is of course not a spot of avoidable machining anywhere. On the other hand, the little essential machining is often beautifully done. (3) They are attached by two or three 7/16" to 5/8" bolts, which generally pass right through them and have big frame washers. These are things that any service man understands and has a right to wrestle with. (4) The oil seal is a leather or other soft packing forced into place like a Welch core-hole plug. They never seem to wear, come loose, or leak. (As we used for years on Lovejoys.) (5) There is no oil filter, since they are filled with clean oil at the factory and expected to "stay put". (6) Arms are very heavy and rigid. Everything is done to avoid flexibility in the instrument or mounting. I think the idea that a certain amount of flexibility in the instrument is desirable is entirely wrong. If softness is wanted, it can so easily be provided by suitable small leakage without introducing undamped flexibility, or throwing away a good proportion of the effective stroke. (7) Attachment of the axle is universally by rubber bushed connections. In no case is lubrication called for on any part of the instrument. (8) I think it is true to say that generally the maximum ball load on rebound is allowed to run up to several hundred pounds, when the valve opens. Harshness is avoided by leakage in the circuit. If you want to see samples of any of these, just let us know and we shall be pleased to get them for you. Kindest regards Yours truly, Maurice Olley B | ||