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 modifications for the 'Goshawk II' piston and connecting rod.
| Identifier | WestWitteringFiles\F\May1921\ Scan32 | |
| Date | 28th May 1921 | |
| To D.A. from E.{Mr Elliott - Chief Engineer} Copy to Gd. " WGR. " HS.{Lord Ernest Hives - Chair} " HY.{Tom Haldenby - Plant Engineer} X4224 " E.O. X4223 RE "GOSHAWK II" PISTON AND CONNECTING ROD. Since it is possible to obtain the dimensions we require on the connecting rod without machining, Mr. Royce wishes to use a taper stem. We therefore shew you the dimensions for this on the attached drawing Lec.1399. Incidentally the width of the stem section has been reduced as being more suitable for the un-machined rod and the general design. A wavy oil pipe has been shewn for feeding the little end, and this is fixed at the bottom end by expanding in a taper hole, and at the top end by sweating. It is not convenient to sweat at the bottom end on account of the whitemetal, while at the top end the soldering has a more suitable attachment on account of the hole into which the pipe is pushed being short, and the solder-ing is considered safe under car conditions of running, especially on this small engine. The double scale view on the drawing shews the method of inserting the oil pipe. A milling cutter is used to make suitable places for the drill forming the oil pipe holes to break into, and the same cutter is also used to machine stations for the oil pipe clips to be sweated to. Fig. 3 on the drawing shews the larger dimensions for the big end and little ends which you set out on your stamping sketch E.50304F, but Mr. Royce does not want to depart from the sizes originally shewn on the drawing Lec.1395, and shewn in fig.2 on Lec.1399. Fig. 2 shews how the underside of the small end boss should be formed to leave sufficient metal for the oil pipe. For the purpose of obtaining a cheaper and simpler job on the connecting rod bolt heads, Mr. Royce would like the feature which prevents turning enlarged to half the circle of the bolt head. Referring to the lubrication of the small end and piston pin, it will be necessary to plug the hole in the top of the small end. Mr. Royce thinks that a taper plug held in by metal peaned over will be quite satisfactory at this point. The grooving for the whitemetal in the big end of the connecting rod should be as shewn. Drawing Lec.1399 also shews a modification to the "Goshawk II" piston. Mr. Royce wishes to use four evenly pitched .100" wide rings as being more practical than the five rings .075" wide. He also wishes the oil collecting groove and holes to be made larger as shewn, since this latter move is reported to be beneficial. E.{Mr Elliott - Chief Engineer} | ||