An Ingenious Generator-starter Gear
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The New Bithell Automatic Apparatus Permits the Employment of a Single Instrument for Generating Current and Starting the Engine
nN a commercial-vehicle engine it is X./desirabIe to run the dynamo at approximately crankshaft speed, and the starter-motor considerably faster. Largely for this reason, it has become customary to employ a separate instrument for each purpose, although the use of one auxiliary would afford obvious advantages.
The accompanying drawing shows a device incorporating a gear reduction and a direct drive which are alternately brought into operation by an automatically controlled coupling, thus obviating the need for two instruments. It is the invention of Mr. W. J. Bithell, 41, Whitehall, London, S.W.1.
On the dynamo-motor shaft is keyed a coupling (A) having on its face slightly undercut ratchet teeth, and incorporating a small gearwheel. The former engages with a correspondingly toothed sliding sleeve or dog (B) and the latter with the large wheel of a double gear running on a countershaft. The small wheel of the double gear meshes with a fourth wheel, free to turn on the engine shaft (which may be an extension of the crankshaft or coupled to it by gears or chain) and having on its face further ratchet teeth (C). These engage with those on the opposite face of the clog B, •the last named being splined to the engine ahaft.
The dynamo-motor shaft is spigoted in the engine shaft, and the gear on the latter is held to the right (as drawn) by a spring which will yield under any pressure originated by the sliding dog (B).
Assuming the dynamo-motor to be mounted at the front of the crankshaft, it will rotate in a clockwise direction (as viewed from the right). When in use as a starter, its initial action is to throw B in engagement with C. Rotation is then transmitted through the gears to teeth C, and thence by the sliding sleeve (B) to the engine shaft, the last-named running, of course, at greatly reduced speed.
So soon as the engine begins to run under its own power, B receives the drive from the plines, overtakes C, and is pushed, to the right, into engagement with A, which will still, but only for . the moment, be rotating more rapidly than it. Thereafter the engine shaft transmits power, through the sliding sleeve, to the dynamo-motor, which runs as a generator at the same speed as the engine shaft, while the gears turn idly until required again for starting purposes.