# Mechanics of Engineering and of Machinery Volume 3, PT. 1,

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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. 1890 edition. Excerpt: ...the vertical deviation See Iferzberg. Die Naehmachine. of the centre line of the groove from the crank circle C C, C, Now, since the centre line of the groove between A and A is a circular arc described with crank radius A C from a centre A, which is located vertically above A a distance A A, = C, A, at the instant when the crank assumes the position A C, the needle bar will come to rest and remain in this condition while the crank turns from A C, to A C3, after which the needle bar again rises. We can see from the figure that the beginning of a period of rest of the needle bar, represented by the crank position A C, does not correspond to the lowest position of the needle, for this lowest position corresponds to the crank position A C, for which the vertical distance C, A included between the crank circle and the middle line of the groove is a maximum. The motion therefore takes place in such a way that the needle moves downward a distance A C, while the crank turns through C A and then it moves from this lowest position a distance C, A- A while the crank is turning through an angle C, A C, whereupon it comes to rest, giving the shuttle an opportunity to pass through the loop of thread formed by the slight rise of the needle from its lowest position. The inversion of the mechanism in Fig. 623 is occasionally employed, the eccentric disk being stationary and the slotted rod receiving, in addition to its reciprocating motion, a rotation about the axis. On this depends the well-known "elliptic chuck," Fig. 629. Here the circular ring D is eccentric to the axis A of the lathe, being fastened to the head-stock L by screws S. The rod here assumes the form of a plate Fto which the work is fastened, this plate being...