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Aviation History
1909
1909 - 0193.PDF
APRIL 3, 1909. direct pressure of the copper upon supporting collars, •which are provided as an abutment .round the cylindrical valve-chambers which project above the cylinder head. Similarly, in connection with the " Flight " Copyright Photo. GREEN AERO-MOTOR.—Copper water-jackets, providedwith sliding expansion-joints, are employed, and many other original details have been embodied into the designof this engine, which is otherwise of the orthodox 4-cyl. vertical type. joints round the ports for the induction and exhaust pipes, which are made tight by the use of flanged ferrules. Owing to this method of construction a damaged jacket can at any time be removed and <*rvn * e/y -*»«^ V~f replaced withoutU difficulty, as the joints can be madeCliApfm% anc^ re~made with- j^JkM^L out losing any- Wm^M %tm^ thing of their original security. Anotherimportant point, too, is thattne ' s^eet copper being quite thin is likely to merely bulge instead of bursting should the water in the jackets freeze, and indeed this has already happened, when, on the occa- sion in question, the jackets were not only unbroken but remained in a sufficiently good condition t o enable the engine to be run alter an artificial thaw. The valves remove complete with their cages and seatings, and the valve-springs and stems are neatly enclosed under aluminium domes, which incidentally " Flight" Copyright Photo. Green Aero-Motor.—View showingthe component parts of which a cylinder is built up. The copperjacket is fastened by the ferrules and nuts shown separately, and at itslower end makes a sliding joint over a rubber ring held in thegrooved flange on the cylinder casting. " Flight" Copyright. Green Aero-Motor.—Sketch showing how the rock-levers hinge back uponthe cam-shaft to enable the valves to be removed. form the locking nuts that make the water joint at the upper end of the cylinder jacket. Another interesting point about the valves is that their stems are turned with a thick and a thin diameter, in order that, should a valve- stem break, the fracture will occur somewhere in the thin part, thereby leaving the thicker portion of the stem which is adjacent to the valve-head still inside its guide when the valve drops. This little precaution is designed to ensure that a ridge on the cylinder casting, which is provided for the purpose, shall invariably prevent a broken valve from dropping into the cylinder. A single overhead cam-shaft is em- ployed to operate the valves through rock-levers, which are themselves en- closed in oil-tight casings, and are so mounted that the whole casing can be hinged back out of the way when a valve has to be removed. The cam-shaft itself is driven by skew gearing from a vertical shaft, which is itself skew-gear-driven from a wheel on the crank-shaft. Although not so arranged on the model exhibited, the proper position for this vertical shaft is between the second and third cylinders, where it performs the supplementary duty of driving a transverse shaft passing through the crank-chamber between the second and third cranks. On opposite ends of this transverse shaft are the magneto and circulating- pump, and on the bottom end of the vertical shaft is the oil-pump. The crank-shaft itself is supported in five bearings, having a total length of 1 foot. The bearings are independently capped and the bolts pass right through the crank-chamber and the cylinder-flanges. It is these same bolts which hold the cylinders to the aluminium base-chamber. The lower half of the base-chamber, which is an oil sump, is formed by a light sheet of aluminium. The cylinders are slightly desaxe. N.E.C. (NEW ENGINE MOTOR CO.). The New Motor Engine Co. have introduced a two- cycle engine embodying the new principle of internal air cooling, whereby a fan is employed to maintain a blast of cooling air through the cylinder during the last half of each working stroke. The stroke is 4 ins., and the exhaust ports open when the piston has travelled half- way, the exhaust discharging through the usual pipe into the silencer. When the exhaust port has been open about |-in. the inlet ports commence to uncover and the air blast is admitted, driving out what happens to be left of the products of the combustion. This air blast remains in action during the rest of the stroke in order to internally cool the cylinders, which it is enabled all the more effectively to do because it comes directly into contact with the hottest members, including the pistons. The hot air is blown out through a continuation of the exhaust ports into a large aluminium chamber which surrounds the cylinders and has an exit direct to the atmosphere. As the piston returns the inlet ports begin 195
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