Fig. 75. Clutches. - This is a piece of mechanism which is required in so many kinds of machinery, that we show several of the most approved types.
Fig. 76. Ball and Socket Joints. - The most practical form of ball and socket joints is simply a head in which is a bowl-shaped cavity the depth of one-half of the ball. A plate with a central opening small enough to hold in the ball, and still large enough at the neck to permit the arm carrying the ball to swing a limited distance, is secured by threads, or by bolts, to the head. The first figure shows this.
Fig. 77 illustrates a simple manner of tightening the ball so as to hold the standard in any desired position.
Fig. 78. Tripping Devices. - These are usually in the form of hooks, so arranged that a slight pull on the tripping lever will cause the suspended articles to drop.
Fig. 79. Anchor Bolt. - These are used in brick or cement walls. The bolt itself screws into a sleeve which is split, and draws a wedge nut up to the split end of the sleeve. As a result the split sleeve opens or spreads out and binds against the wall sufficiently to prevent the bolt from being withdrawn.
Fig. 80. Lazy Tongs. - One of the simplest and most effective instruments for carrying ice, boxes or heavy objects, which are bulky or inconvenient to carry. It grasps the article firmly, and the heavier the weight the tighter is its grasp.
Fig. 81. Disc Shears. - This is a useful tool either for cutting tin or paper, pasteboard and the like. It will cut by the act of drawing the material through it, but if power is applied to one or to both of the shafts the work is much facilitated, particularly in thick or hard material.
Fig. 82. Wabble Saw. - This is a most simple and useful tool, as it will readily and quickly saw out a groove so that it is undercut. The saw is put on the mandrel at an angle, as will be seen, and should be run at a high rate of speed.
Fig. 83. Crank Motion by a Slotted Yoke. - This produces a straight back-and-forth movement from the circular motion of a wheel or crank. It entirely dispenses with a pitman rod, and it enables the machine, or the part of the machine operated, to be placed close to the crank.
Fig. 84. Continuous Feed by the Motion of a Lever. - The simple lever with a pawl on each side of the fulcrum is the most effective means to make a continuous feed by the simple movement of a lever. The form shown is capable of many modifications, and it can be easily adapted for any particular work desired.
Fig. 85. Crank Motion. - By the structure shown, namely, a slotted lever (A), a quick return can be made with the lever. B indicates the fulcrum.
Fig. 86. Ratchet Head. - This shows a well-known form for common ratchet. It has the advantage that the radially movable plugs (A) are tangentially disposed, and rest against walls (B) eccentrically disposed, and are, therefore, in such a position that they easily slide over the inclines.
Fig. 87. Bench Clamp. - A pair of dogs (A, B), with the ends bent toward each other, and pivoted midway between the ends to the bench in such a position that the board (C), to be held between them, on striking the rear ends of the dogs, will force the forward ends together, and thus clamp it firmly for planing or other purposes.
Fig. 88. Helico-Volute Spring. - This is a form of spring for tension purposes. The enlarged cross-section of the coil in its middle portion, with the ends tapering down to the eyes, provides a means whereby the pull is transferred from the smaller to the larger portions, without producing a great breaking strain near the ends.
Fig. 89. Double Helico-Volute. - This form, so far as the outlines are considered, is the opposite of Fig. 88. A compression spring of this kind has a very wide range of movement.
Fig. 90. Helical Spring. - This form of coil, uniform from end to end, is usually made of metal which is square in cross-section, and used where it is required for heavy purposes
Fig. 91. Single Volute Helix-Spring. - This is also used for compression, intended where tremendous weights or resistances are to be overcome, and when the range of movement is small.
Fig. 92. Flat Spiral, or Convolute. - This is for small machines. It is the familiar form used in watches owing to its delicate structure, and it is admirably adapted to yield to the rocking motion of an arbor.
Fig. 93. Eccentric Rod and Strap. - A simple and convenient form of structure, intended to furnish a reciprocating motion where a crank is not available. An illustration of its use is shown on certain types of steam engine to operate the valves.
Fig. 94. Anti-Dead Center for Foot-Lathes. - A flat, spiral spring (A), with its coiled end attached to firm support (B), has its other end pivotally attached to the crank-pin (C), the tension of the spring being such that when the lathe stops the crack-pin will always be at one side of the dead-center, thus enabling the operator to start the machine by merely pressing the foot downwardly on the treadle (D)