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).
Preliminary specification for an 18HP vehicle, covering engine, chassis, and design choices.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan319 | |
| Date | 20th July 1931 | |
| S.G. FROM R.{Sir Henry Royce} (crossed out) C. to WOR.{Arthur Wormald - General Works Manager} HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} (crossed out) C. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} (crossed out) ORIGINAL PRELIMINARY SPECIFICATION FOR 18HP. X5770. This is to follow almost exactly J.{Mr Johnson W.M.} 3., the engine being the same at a scale of .81 = 2.75 (70.mm.) bore, and 4.125 (105.mm.) stroke. The chassis frame will be long enough for a good four seater but just too short for a 6 seater. The frame passes over the rear springs and the brake drums will be nearly buried under the tyres, so that the frame is very wide at the back and the rear cushioning goes between the frame and is struck by the centre of the rear axle on extreme bump - i.e. clearance being too little by about 1". This is to get the floor, roof, and centre of gravity low and less inclined to roll at corners with flexible springs. The lower the centre of gravity the more possible it is to have flexible springs with high speed. The wheelbase will be 10 ft. and the track 56" at front, and 57" or 58" at rear, with splashers parallel. If this model doubles our output certain accessories will be made in larger quantities and could be included at cost, and yet help to make a profit. When looking over the designs of Buick, Humber, etc, we find they get together quite complicated chassis for remarkably little money - i.e. as I have before explained we cannot make anything like the required difference by altering the design that is needed: we can do say 10% in the required 50%. It will also be understood that some of the smart looking things are mechanically bad, and are not reliable for their purpose. Some are false, some will look bad after 12 months use - tinny, rusty, and bent - so that we must still have faith in our thoroughness and be content to look like ladies rather than smart painted women in tawdry clothes that won't wear. The wheels will have 18" rims and be fitted with 5.5 tyres. Small wheels will make the appearance nearer to those of a large car as well as get the floor lower: (for Colonial export where greater ground clearance is needed wheels of larger dia. can be used.) It is intended that we trust to the bodies for torsional stiffness of the frame, but we shall be using the weight of the engine to fit frame dampers in addition to the ordinary hydraulic axle dampers. For low cost we ought to use oil-less bushes for the springs, but we should then be cutting out our spring leaf oiling, in fact the whole of the central oiling, and I fear this would be losing a valuable RR. feature which would help to demand our extra price, (but this oiling sch. costs much in fitters' time.) R.{Sir Henry Royce} | ||