Free-piston Engines: Maker's Forecast
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VEHICLES for which the free-piston engine will first be employed are heavy earth-moving machines, crawler tractors and similar outfits. This information was given by Mr. B. MeNaughton, of the Free Piston Co., Ltd., to members of the Institute of Road .Transport Engineers in Birmingham, on Tuesday. They were discussing his paper on the value Of the free-piston engine for automotive uses.
The problem of starting might be overcome, he said, by using a vacuum to move the compressor pistons to their outer limits, after which pressure would be applied by opening a valve to a starting bottle. The normal time lag of two or three minutes when starting from cold. could be • reduced by. employing some form of additional heat.
Speed control presented difficulties, of which there were many possible solutions. Joint control of both the gasifier and turbine was required to provide a ready response to changes of pedal position. Ignition timing could, be controlled by a.-cushioning• cylinder sensing device.
A free-piston engine would probably be no noisier than a conventional oil engine of similar output. Exhaust gases' were discharged at a pressure of about 46 p.s.i. A sampling device ensured that the volume of air in the cushioning cOnder was kept constant. .
Certain lubrication difficulties had yet to he overcome in the development of small units, Mr. McNaughton said. Rates of wear could not be accurately estimated. They had at first been high in large industrial units, but were now satisfactory.
On average, a large engine would run 3,000-4,000 hours between the replacement of parts. Pistons could be removed and replaced in an hour. , • In a vehicle, one or more gasifiers could he employed to operate separate turbines driving the road wheels. The distance between the gasifier and turbine was note of great importance.
BUSES FOR COUNCIL STAFF HEN Derbyshire County Council move into their new offices in Matlock, 10 buses may be used to take staff from Derby every day,arriving at Matlock by various routes. It • was originally • intended that special . trains should be employed, but use of buses is understood tri have been recomthended by the National and Local Government Officers' Association. • . . . • • . NEW £1,475,000 MOTORWAY
110tY-f'ASSING Dronficid and Unstone. I-) a new £1,475,000 motorway is planned to connect Sheffield and Chesterfield. Preliminary-survey work has been completed and contracts may be let by March, 1962. A link with the proposed Chesterfield By-pass will be built later to provide a fast route from Sheffield to the Midlands.