Potted Power
Page 49
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Supplied by Cartridge
I.C.I. Method Has Wide Applications DEMONSTRATED last week at the explosives division, Ardeer, of Imperial Chemical Industries, Ltd., the cartridge presents power in a compact and portable form and has potentialities covering a wide mechanical field. The power-cartridge principle is a modification of the process by which a gun is fired. In a gun, the fired charge produces a large volume of gas almost instantaneously, whereas in powercartridge operation the energy is released more slowly and is harnessed so that it may be translated into useful work.
Mechanical Application
This is generally done by the pressure of gas either on the head of a piston in a cylinder, or by impact on the blades of a turbine, although such auxiliary mechanisms are not necessary for all its applications. The gases from the cartridge may be evolved over periods ranging from a fraction of a second to a few minutes, The Bristol Aeroplane Co., Ltd., has adopted power-cartridge operation for the emergency lowering of undercarriages on Beaufort and other aircraft. It could be similarly adapted to a wheel-jacking system for heavy commercial vehicles, and within a few seconds of the cartridge being fired, the wheel would be raised from the ground. Considerable time 'would be saved by using this method, at the cost of a replacement cartridge, which at the moment is under Is. As this system becomes adopted more widely, the cost will be lowered.
The PI essey cartridge starter, described in "The Commercial Motor" dated November 21, 1947, was used last week to start an 85 b.h.p. oil engine from cold. Gases generated by firing the cartridge build up a pressure over the starter piston, causing it to move forward so that its dog engages with the dog attached to the end of the crankshaft. This turns the crankshaft . through .three-quarters of a revolution and the impetus of the engine enables it to make a further 2-3 revolutions at a speed of 200-300 r.p.m., which is more than sufficient to start the engine.
Two-stroke engines were started, in a tractor and in a refrigerator, using the cartridge " direct-injection " method. the gases being led into the cylinder head through the decompression valve. For this application it is necessary to set the flywheel to a position which ensures that the piston is slightly over top dead centre.
Initiating Fire Quenchers
Water drencher systems, initiated by the power cartridge, can contribute Co the safety of personnel and plant in industrial operations involving the risk of sudden fire. A photo-electric cell detects the first flame or flash and the current produced, suitably amplified, fires a small cartridge. This in turn can be used to lift a large-diameter valve and the potential fire is put out in less than a second of the initial flash.
There are many applications for the power cartridge, a few examples being the punching of holes in metal plates, engraving on metals, setting studs in position, operating portable fire extinguishers and tyre inflation.