Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900 edition. Excerpt: ...from that on the spherical surface for the portion of the curve that is used for teeth of the ordinary proportions'. The conical surface BPF can be developed on the plane surface of the drawing-paper by cutting it down any element and allowing it to unroll. If it is cut down the element BP, the line which was tangent to the base of the pitchcone will develop in a circle with B as a centre, a portion of which is shown as PQ, and the teeth will develop as shown. The same process can be applied to the pitch cone AEP. In order to lay out the large end of the eeth by this method when the pitch cones are determined, AB is drawn perpendicular to OP, intersecting the axes of the gears at A and B. The last two points are then used as centres for describing the arcs PR and PQ of indefinite length, only enough of them to allow the development of a few teeth being required. Then, using these arcs as portions of pitch circles, the teeth are developed upon them as is done for spur gears, according to any system that may be selected. It must be kept in mind that the pitch and number of teeth must be such that the required number will go on a pitch circle of the diameter PF or PE. Fig. 62 shows a partial section of the common form of a pair of Fig. 62. bevel-gear blanks and the method of showing the development of both ends of the teeth. If the method used for the larger end were followed exactly for the smaller one. A ' and B' would be used as centres for the inner ends. For convenience and a clearer way of comparing the two ends, the distance Aa is taken equal to A'P', and A is then Used as a centre for the auxiliary pitch circle on which the teeth of the inner end of the gear arc developed. The same method is applied to the other gear of the pair. In...
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