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the special purpose of driving a dynamo direct from the flywheel for electric lighting, for which purpose their practice is to have large diameters in the cylinders, comparatively short strokes, and heavy flywheels running at a very high rate of speed-viz. from 250 to 350 revolutions per minute. The crank shaft is balanced by means of weights placed in the flywheels, so that they move at the same mean velocity as the parts to be balanced, although at considerable distance from the centre line of the cylinder. The gas, air, and timing valves are placed horizontally

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FIG. 12.-CROSSLEY'S HIGH-SPEED ELECTRIC LIGHT ENGINE

on the side of the cylinder, with the exhaust valve vertical. A centrifugal governor is used combined with the pecker action. The same proportions and practice are used in a tandem and quadruple design; the former being, like fig. 10, a combination of a right and left hand engine, having, however, only one flywheel and outer bearing. The quadruple engine giving two impulses per revolution when working at full power is practically a double tandem engine, with one flywheel between the two engines, having discs and overhanging crank pins instead of the ordinary

crank shaft with double jaws, and one governor to control the whole.

It seems more than possible that makers of these excessively high-speed engines will find that much better results can be obtained by using a long stroke, balanced engine, with larger flywheels running at a slower speed.

The misleading term of 'NOMINAL HORSE-POWER' is happily not used in these engines, each size being rated at its effective

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power. And it would be well if the same principle were applied to all sizes, and instead of calling-say, fig. 13- H.P. NOM., it were rated as a 2 B.H.P. This engine contains some of the features of the high-speed type, in that the air and gas valves being placed horizontally in one box are easily disconnected from the engine if necessary, although the horizontal position is not good practice. It is governed by Holt's effective inertia governor, worked by a small crank on the end of the cross

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FIG. 14.-3 H.P. NOM. VERTICAL CROSSLEY ENGINE (SECTIONAL ELEVATION)

shaft, and has no timing valve, and, unlike the general practice of this firm, is not provided with a renewable liner to the cylinder.

All the engines previously described have been of the horizontal type, but as there are many positions where, from considerations of room, it would be impossible to fix a horizontal

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FIG. 15.-3 H.P. NOM. VERTICAL CROSSLEY ENGINE (SECTIONAL PLAN)

engine, it has been found necessary to make a vertical one, and figs. 14, 15, and 16 show in section, plan, and external elevation such an engine of 3 H.P. NOM. The cylinder being 7 inches diameter by 10 inches stroke, is formed by forcing a liner A, by means of a gland B, into the main casting C, and leaving an annular space between the two to form a water jacket. The

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joints are made at the bottom by asbestos to withstand the heat, and at the top by a rolling rubber ring D. In all respects this is an almost ideal engine of a vertical pattern.

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FIG. 16.-3 H.P. NOM. VERTICAL

CROSSLEY ENGINE

The valve arrangement is simplicity itself. The box E, which is easily disconnected, contains the gas, air, and exhaust valve. The gas valve F is connected by the passage G to the gas cock shown in the elevation. The air valve H and exhaust valve I, whilst having the same passage, J, to the cylinder, have separate passages in the box E. The air is drawn through the silencer K, and the exhaust outlet is shown at L.

The Clerk-Lanchester pressure starter is used by these makers, and fitted to all large-sized engines.

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Diam. Wide Diameter Wide

n
in. Revs.
31 200

in. in.

43

10

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4 8

200

12

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Bore of

Cylinder
Length of
Stroke
Diameter of

Crank Shaft

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