Excavating Machinery (Paperback)

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. 1913 edition. Excerpt: ...and winds up the chain or cable, which in turn unwinds from the other or loose drum. The advantages of this method are the cheapness of construction and economy of space in using one engine. The disadvantages are the necessity of using the hoisting engine in order to operate the swinging device, the difficulty of keeping the swinging cable or chain taut and the waste of power. In nearly all makes of dredges over 1 cu. yd. capacity a separate swinging engine is used. The type of engine used is one which is reversible and operated by a balanced throttle valve. The engine is compound geared to a long shaft, having two drums placed at such distance apart so as to give a direct pull to the swinging circle on either side. A chain or steel cable extends from the bottom side of one drum to the swinging circle or turntable and thence to the top side of the other drum. Where it is desired to swing the boom, the Combined Hoisting and Swinging Engine of Floating Dipper Dredge. Figure 78. Swinging Engine of Floating Dipper Dredge. Figure 79. swinging engine is operated and the cable or chain winds up on one drum as fast as it unwinds on the other. A typical swinging engine is shown in Fig. 79. The swinging circle or turntable may be either fixed or movable and may be placed either just above or several feet above the deck. For dredges of dipper capacity up to 2 cu. yd. most manufacturers use a solid deck swinging circle. This consists of drum-shaped framework of steel plates and a side web of channels. In the center of the circle is a large cast ring, which rests and revolves upon the main base casting, which is fastened to the front edge of the deck. The lower end of the boom is pivoted on this cast ring and revolves with the swinging circle. Several...