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SHOP TOOLS.

small aperture A., fig. 23, by means of a simple hydraulicvalve shown by fig. 26. The water entering at B tends to keepthe inlet valve C shut, the spring D serving the same purposeuntil the accumulator pressure begins to act. On opening thevalve C (by the hand lever E) water is admitted to the cylinderand passes into it against the ram (8 inches diameter), until therivet is closed. The exhaust valve E is kept shut by thepressure of water entering the cylinder, and at other times bythe spring D, but by pulling the lever over the reverse way theexhaust valve is opened, by which the exhaust water eseapes tothe cistern, a small portion being allowed to flow through thepipe G- (fig. 23) on to the die, to cool it. The ram H is drawnback by means of the small drawback cylinder J (fig. 27),which is arranged within the ram itself, and is in constantcommunication with the accumulator through the inlet K.The wedge-shaped fastening of the disc (as shown at L infigs. 23 and 25) obviates any thickness of metal over thefixing pin ordinarily employed to keep the die in its place.This enables the rivetter to be used for rivetting flanged andangled iron work.

The success which resulted from the use of water-powerwlien applied to the fixed rivetters, led to its application to aportable rivetter, which was able to be taken to the work, in-stead of the work having to be brought to the rivetter.

Figs. 28 and 29 show a sectional elevation and end elevationof one of the portable hydraulic rivetting or punching machines.In the cylinder A is a plunger or ram B, with two jaws CC, towhich is attached a cross-head or horn D, furnished at one ofits ends with the cupping die E. The plunger B, being forcedforward, by water admitted through a valve by the gearing F,the cross-head advances until it meets the resistance of oneend of the other cross-head Gr at a point H, which is shapedto receive J, and at the other it comes in contact with, andcloses, the rivet, or punches or shears the plate, according tothe purpose it is used for. At the same time the outside cross-head (or one farthest from the cylinder) is held up against the