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).
Design specifications and required testing for an adjustable collapsible piston with a hairpin spring.
| Identifier | ExFiles\Box 41\1\ Scan078 | |
| Date | 5th January 1920 | |
| To Da.{Bernard Day - Chassis Design} from E.{Mr Elliott - Chief Engineer} Copy to CJ. " " Bn.{W.O. Bentley / Mr Barrington} " " Hs.{Lord Ernest Hives - Chair} " " Ck.{Mr Clark} X 3776 E4/G5.1.20. X.3776. - RE ADJUSTABLE COLLAPSABLE PISTON. ------------------------------------------ We send to you on Saturday the 3rd inst. drawing LeC.1180 shewing an adjustable collapsable piston in which a flap or pad on the aluminium piston was pushed out against stops by the action of a steel hairpin spring. This spring should give a pressure normally of about 120 lbs.. when the maximum stress in it should be within the neighbourhood of 80,000 lbs. per sq. inch. The spring should be machined from the solid and tempered with a clamp on its free ends, so that it will not distort and upset its normal load. The spring is assembled on the piston by inserting it from the inside and it may be necessary for you to design a little faitting to assist this assembling operation. I was not able, before sending the drawing, owing to lack of time, to work out the stress on the aluminium hinge section that the unrestrained pressure of the spring would cause, but hope that the aluminium hinge section is strong enough to withstand the spring pressure during assembling without the help of a stop or clamp. If this is not so, it is very easy to use a clamp. On the 4th inst., a further note was send with regard to this piston, asking you to incorporate a "stop in" as well as a "stop out", so that if the inertia load of the piston overcomes the spring pressure at very high rates of re-volution, the pad will not close in beond a fixed point. Would you kindly instruct the necessary material for the tests desired. E.{Mr Elliott - Chief Engineer} | ||