A Treatise On The Principles And Practice Of Dock Engineering

TRANSPORTERS. 537 with gun-metal plungers, 3|| inches in diameter and 14 inches stroke. All the levers for actuating the starting and stopping valves and gearing generally are arranged so as to be worked by one man standing upon a platform, raised above the lower framework of the crane. Turning motion is effected through spur and bevel gearing, acting on a toothed rack on the outer edge of the lower roller track. All the machinery pipes and valves, subjected to a working pressure of 700 Ibs. per square inch, were tested to 1,400 Ibs., and the cylinder, piston- rod and piston, links, <fcc., were tested to 320 tons, or double the working load. Transporters.—A transporter consists essentially of a long arm or track, placed horizontally or very nearly so, along which travels a carriage with a hook for the attachment of loads. There are several types of transporter ; two will be briefly described. The Temperley Transporter consists of an iron beam of H section, supported by a special tower, by the mast of a vessel, or by the underside of a shed floor or roof. The traveller, or truck, is provided with an arrangement for throwing itself automatically out of gear at fixed positions vertically over the points of loading and discharge. It is actuated by a steel wire cable, which can be set in motion by steam, hydraulic, or electric power, and also by gas engines for lower speeds. These transporters are applicable to loads of from 5 to 60 cwts., and to distances up to 1,000 feet, with travelling speeds ranging from 500 to 1,500 feet per minute. A view of the transporter is shown in fig. 554. The traveller, at the left end, contains automatic mechanism which secures it to the beam during the lifting of the load, and which sustains the load during the movement of the traveller. The load having been attached to the hook in its lowest position, the latter is hoisted by a hydraulic or other engine until the fall block enters the bell of the traveller, when two hooks automatically engage the block and sustain the load, while, at the same time, the traveller is released from the notch in the beam and commences to travel into the building.