HYDRAULIC CRANES.—The Ridgway Steam Hydraulic Crane has a jib carrying a free trolley, which is suspended by short and very heavy chains passing over wheels on the inclined brace and mast. and are attached to the upper end of a cylinder. The piston-rod of this cylinder is hollow, and is bolted to a projection from the bottom gudgeon. This large and heavy cylinder is used to counterbalance the weight. of the jib. Conveniently located on or in the ground is a closed cylinder. On top of this cylinder is a plain slide-valve, from which one pipe is run to the boiler for steam. and another outside the building for exhaust. From the bottom of this cylinder a pipe is carried to the crane bed-plate connect ing with the passage to the lifting cylinder. The ground cylinder is filled with water to within a foot of the top—air occupying this space. It being now desired to lift the crane. steam is admitted, and being prevented by the air from coming in contact with the water, it does not condense ; the water takes the same pressure as the steam, passes to the crane, where, entering the lifting-cylinder, the latter is pressed down the rod, raising the jib and its attached load. To lower, the steam is exhausted and the water flows back by gravity, and the cylinder rises and the jib is lowered.
A hydraulic traveling-erane, designed by Erwin Graves, of Camden, N. J., is described in vol. xii Trans. A. S. J1. E.
LOCOMOTivE TRAVELING-CRANE.—A form of crane recently adopted for steel-works, arse nals, etc., for very heavy lilting, has a locomotive boiler and engine on one end of the travel ing-bridge, the engine furnishing motive-power through the necessary spur-gearing for the three motions of the crane. This kind of crane is independent of all other motive-power of the works in which it is used, and requires merely to be supplied with fuel_and water at some convenient point in its course.
A Locomotive-Crane, of English manufacture, is represented in Fig. 8. It is intended to lift 10 tons at a radius of 20 ft., and 7 tons at a distance of 25 ft. from the central pillar of the crane, being fitted with a motion which allows this radius to be varied. The hoisting is
done oy a galvanized steel-wire rope, 4 in. in diameter, which is wound on a specially large steel barrel. This barrel is worked by double-purchase spur-gearing, the motion of which is controlled by clutches in the usual way. A powerful friction-brake is supplied for holding and lowering the load. The crane has a revolving motion, consisting of an internal bevel seenred to the frame of the machine, and a pinion gearing into it, the motion of which can be reversed without stopping or reversing the engines.
The crane is propelled by the same engines by means of which its motions are worked, the connection to the wheels being made by bevel gearing. These engines have cylinders 81- in. in diameter, with a 12-in. stroke, and are fitted with a link-reversing mo tion.
.1 40- Tim Tray('linv-Oraite.—The remarkable crane represented in Fig. 0 (called a steam Titan) was built for lifting blocks of concrete weighing 32 tons, used in the construction of the Madras Breakwater. The weight of the Titan, without water - ballast or load, is 159 tons, and with ballast 170 tons. All the motions of the appli ance are under perfect control by means of a set of levers situ ated on a platform, and within easy reach of the single opera tor. A feature of importance in connection with this appli ance is that it not only has to be capable of slewing round in a. complete circle, but has also, owing to the shape of the break water on which it will be em ployed, to be capable of travel ing on a curved road. To en able it to accomplish this, the Titan is carried upon twelve wheels arranged as wheeled bogies, one at each entl, and with driving-wheels in the center. This arrangement enables the Titan to travel with round a of un ft. radius. The radius deseribed by the 111111 is 51) ft., and to minim ize the shock produced by stopping a lead, owing to aequired when being slewed round, devices are introduced in connection with the gearing, to its to bring the arm to a gradual stop.
Crank : see Engines, Steam.