Earth and Rock Excavation; A Practical Treatise (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt: ... for earth, and grabbing-chains for stones. Scales.--Scales are usually made of wood reinforced with iron. They consist of a square platform 3 ft., sides surrounded by boards H ft. high on three sides. Attached to the platform and in the center of the open side of the scale there is an iron ring, and two similar rings are provided at the top of the rear end of the two parallel side-boards. The scale is lifted by placing in these rings hooks attached to the end of a system of three short chains, which are suspended to the hoisting-block. On account of this arrangement, in hoisting the scale the material that it contains will gravitate toward the interior, thus preventing it from spilling from the open side. The unloading of these scales is very simple. When the dumping-place has been reached, which may be either a wagon, a car, a bin, or the spoil-bank, the scale is lowered so as to relieve the chains of the weight. then the front chain is removed from the ring and the scale is slowly hoisted. Being then attached only by the rear rings this part will be raised while the front will continue to remain at rest, and consequently the material will rush to this side and the scale will empty its contents into the required place. Scales are subjected to a great deal of wear and, especially when handling-rocks, they are easily destroyed. In such a case it is more convenient to have them made of steel, like those used in the construction of the tunnels under Park Avenue for the New York rapid-transit railroad. Here the scales employed were 4X4X2 ft., and were made of steel and reinforced pieces of iron. The scales were placed on top of platform cars and loaded with the material at the front of the excavation, and hauled to the bottom of the shaft from which they were ...