Annular Cylinder in New Engine
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A NEW type of engine in which there
are only nine moving parts and claimed to be 50 per cent. lighter, 30 per cent, cheaper to build and to develop 25 per cent, more power than an existing internal-combustion unit of comparable capacity, has been invented by Mr. Granville Bradshaw, Hill Cottage, Eversley, Basingstoke, There are four double-ended pistons working in a circular cylinder or annulus. Opposed pairs of pistons are carried on arms which form integral units with two central discs splined to hollow shafts. These shafts extend, at right-angles to the cylinder and piston assembly, to the crankcase, which forms a separate unit and is not subjected to any direct heat, as in the case of a normal engine, Each hollow shaft at the crankcase end carries a crank arm and a connecting rod through which the movement of the pistons is conveyed to a twothrow crankshaft by a push-pull movement on both.strokes.
Inlet and exhaust ports are formed in the cylinder as in a two-stroke engine, the sequence of events being controlled by the pistons combined with the rotary motion of the cylinder, which revolves at half-engine speed. This combined movement with the pistons oscillating within the cylinder produces a four-stroke cycle utilizing a twostroke porting system.
There is only one sparking plug. This is in the combustion -area only momentarily during the firing stroke, because it ignites the charge at the moment when two of the pistons are fully opposed on the compression stroke.
The cylinder, which moves in the same direction as the pistons, is geardriven by a shaft which runs through the central hollow drive shaft. Mixture is fed to the cylinder by an integral axial fan, so that a degree of supercharge is obtained. Air cooling is adopted and, because of the absence of any form of valve gear, it is claimed that the engine runs as silently as a water-cooled poppet-valve unit.
With two 1,250 c.c. units arranged in V8 formation, it is thought to be possible to produce 350 b.h.p.