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).
The Junkers two-stroke C.I. motor-coach engine, including details from an interview and technical specifications.
| Identifier | WestWitteringFiles\W\September1931-November1931\ Scan087 | |
| Date | 18th November 1931 | |
| ORIGINAL To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/CHP. c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Rg.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/CHP.2/MJ.18.11.31. Y631 Y4433 JUNKERS TWO-STROKE C.I. MOTOR-COACH ENGINE. Two of these engines are exhibited on the Gilford stand at the "Commercial Motor Transport Exhibition", and they are understood to be the only examples of the six-cylinder edition in this country at the present time. During a visit to the above exhibition I obtained an interview with Mr. V.O. Skinner joint managing-director of the Gilford Motor Co. Ltd., of 465 Holloway Road, London, N.7. Mr. Skinner informed me that negotiations with the Junkers Company for the production of their engines in this country were not yet completed; but he hoped that an agreement would be arranged and the production started within three months' time. The engines would not be manufactured at the Gilford Co's. Works, but the job would be contracted for by some other firm; he could not yet say by whom, as tenders are to be invited from several firms when the drawings are received from Germany. Mr. Skinner informed me that, as far as he could see, his firm would be pleased to supply R.R. with a separate power unit for our investigation work, as soon as production was started. He suggested that we communice with his Company in a few weeks' time when they may be able to give us some definite information as to where the engines will be made. He estimated very roughly that the price of an engine to R.R. would be approximately £400, probably rather less. I was unable to obtain much technical data regarding the engine as the Gilford Co., are not yet in possession of full details. The following are of interest, however :- Six cylinders 70 m/m (2.750") bore, each having two opposed pistons of 105 m/m.{Mr Moon / Mr Moore} (4.140") stroke. The total stroke for each cylinder is thus 210 m/m (8.270"). Two crankshafts operated by the lower and upper sets of pistons respectively. The shafts are connected by a train of four gears at one end of the engine, thus they rotate in opposite directions. The crankshafts are phased at 180°, hence there is no lead of one piston over its mate. The clutch is mounted on the lower of the two middle crankshaft connecting gears, from which the power is transmitted to the gearbox. Compression ratio 14:1. | ||