Starting Big Engines by Cartridge
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AT the touch of a button, a large oil or petrol engine can be instantly started with the new cartridge starter developed by the Plessey Co., 'Ltd., Ilford, Essex. This unit has beers produced for commercial use to provide a reliable lightweight starter for engines up to approximately 200 h.p,
No larger than a conventional electric starter, the cartridge type weighs approximately 10 lb. and incorporates a magazine breech which holds six cartridges. Reloading is simple, the barrel assembly of the breech being completely detachable and interchangeable.
Independence of the electrical system is one of the advantages of the cartridge starter. Further, whilst the overall weight compares favourably with that of the electric starter, a saving in weight is also achieved by the appreciable reduction of the necessary capacity of the accumulator and dynamo, It is visualized that spares will be stocked eventually at garages, filling stations and by distributors. A cartridge starter operates on the principle of applying single rotative impulses and, therefore, delivers its full effect in a short space of time This action is not unlike, but more powerful than, a sharp pull on the starting handle.
By using three different angles on the helical spline, three gear ratios have been achieved on the driving dog. The rotation of the starter 'jaw under power is, of course, accortling to the spline arrangement. Rotation of the clutch jaw under power of these starters is 400, 500 and 600 degrees respectively.-whilst the maximum torque is 650, 550 and 450 lb ft respectively.
When a cartridge is fired the gases generated pass into the startet cylinder where a piston is driven down; this movement is converted into rotation of the starter dog by a series of spirally
splined shafts. Initial travel of the piston serves to engage the starter jaw with the engine. This takes place at a low pressure, after which the torque
builds up. ,
All stresses involved are absorbed within the starter itself, only pure torque . being applied to the engine starter jaw. As the piston reaches the end of its working stroke, an exhaust valve is automatically opened and the gases pass to. the atritosphere.
The 'jaw is nerw disengaged from the engine and the'nisionis returned to the top of its stroke-by a powerful spring. On reachingthis, the exhaust valve closes and the starter is ready for a further cycle of • aperations. Indexing the breech by cable • control or push buttOn brings -another cartridge into working position. This cable, the only breech control, requires a 10 lb. maxi
mum pull over 6i ins. travel, The breech is infinitely rotatable around the longitudinal axis of the starter and the control may be aiTanged to suit the requirements of the individual transport operator.