Fig. 2088.
[Fig. 2088] represents a form of leg vice for heavy work. In the ordinary forms of this class of vice the two gripping surfaces of the jaws, only stand parallel and vertical when at one position, because the movable leg is pivoted at p; but in that shown in the figure the movable jaw is supported by the arm a, passing through the fixed leg l, which carries a nut n. A screw s, having journal bearing in the movable leg, screws through the nut n, and is connected to the upper screw by the chain c, which passes around a chain wheel provided on each screw, so that the movable leg moves in an upright position and the jaw faces stand parallel, no matter what the width of the work. This is a very substantial method of obtaining a desirable and important object, and greatly enhances the gripping capability of the vice. [Fig. 2089] represents a sectional view of another patent vice. a is the sliding and b the fixed jaw. p is the bed plate carrying the steel rack plate h. Attached to each side of the base of the handle is a disk. These disks are carried on the outer end of the movable jaw a, and are held in place by the friction straps t, adjusted by the screws s. On the radial face of the disk is the pin k, which, when the handle or lever is lifted or raised, depresses the end of lever j, which at its other end raises the clutch g, disengaging the same from the rack h, as shown in the engraving. The jaw a is thus free to be moved by hand, so as to have contact with the work. To tighten the vice the handle is depressed, whereon k releases j and the latter permits the toothed clutch g to engage with the teeth of h. At the same time the bar d, which is pivoted to the disks, is drawn outward. The end of the bar d, meeting the surface of the lug shown on a, acts (in conjunction with the toothed clutch h) as a toggle fulcrum from which the disks may force the movable jaw to grip the work.
Fig. 2089.
This action may be more minutely described as follows: The end d of d is pivoted upon the disks, as shown; hence when the handle is depressed the effort of the end d is to move to the right, but d being fixed at the other end the pressure is exerted to force the movable jaw to the left, and therefore upon the work. The amount of jaw movement due to the depression of the handle is such that if that jaw is pushed near or close to the work the handle will stand about vertical downward when the vice firmly grips the work.
For vices whose jaws cannot be swiveled horizontally to enable them to conform to taper work, attachments for the jaws are sometimes provided, these attachments having the necessary swiveling feature. So likewise for gripping pipes, and similar purposes, attachments are made having circular recesses to receive the pipes.
