The Mechanical Handling and Storing of Material

COAL TIPS OR HOISTS 5*7 cradle is then ready to receive another wagon. Crane N and lowering device p are employed in order to minimise breakage. By the use of tips of this construction a height of 9 ft. is lost by having to lower the cradle sufficiently to tip the wagon. A gradual increase in the size of the ships to be loaded rendered it necessary to prevent this loss of effective height in the tips, in order to raise the shoots to the level required by the increased height of the decks of the ships. Instead of lowering the cradle, therefore, the tail end is hauled up by a winch worked by hand, thus converting it into a tip discharging on the level of the rails instead of below. This tedious process was subsequently superseded with great advantage by hydraulic machinery, consisting of a simple Armstrong crane cylinder with a 9-in. ram and double pulley connected to the tipping chain. This system has been adopted in reconstructing the old balance tips at both the east and west docks at Cardiff. 1 he first balance tips constructed at the west docks received the wagons on the cradle at a level of 18 ft. above the quay, but the increased size of the ships to be loaded has necessitated raising the railway and the framing of the tips 3 ft. higher, making the level for the wagons at the west dock 21 ft. above the dock coping, or 22 ft. above the water. '1 he coal tips at the east dock were originally constructed at this higher level, but in consequence of such large vessels being loaded there, the height of the additional tips constructed has been further increased by 6 ft., giving a height of 27 ft. above the coping. As it is necessary to adjust the level of the shoot to the actual height of each ship, in order to reduce breakage of coal as much as possible, the heel of the shoot is attached to the frame of the tip so as to slide in a vertical groove. The shoot is carried by adjustable chains with balance weights and winches, so that the inclination as well as the height of the shoot can be changed if necessary.1 This short history has been given here for the sake of completeness, although the converted tips really belong under heading B. Hydraulic Tip at Dortmund.—A hydraulic coal tip of some interest is at work in the harbour of Dortmund in Germany. It is on the Schmitz-Rohde principle, and was built by Friedrich Krupp, Grusonwerk, Magdeburg. This tip consists essentially of a platform swinging on a horizontal axis. The coal trucks are pushed on to this platform and tip with the latter, emptying themselves over the end into the barge. The apparatus works without the expenditure of outside power, so that there is no necessity for a motor. The principle is to utilise the energy due to the weight of the contents of the truck when lowered, and to store it in an accumulator, to be used again for raising the platform and truck when the latter is empty. This is a great improvement on similar installations in which this energy is lost by absorbing it in a brake, as in that case motive power must sometimes be provided for lifting the truck. The tip can be used for the rolling stock of all the lines which bring coal or coke to the harbour of Dortmund, and for loads of 10 to 15 tons, the only condition being that the trucks are fitted with hinged end doors. Figs. 723, 724, and 725 illustrate the tip. a is the platform which swings round the trunnion G. The forward end of the platform is suspended by the hydraulic ram f of a movable supported cylinder b. To the other end of the platform a balance weight is attached. Ihe cylinder b communicates with an accumulator d, the connection between the two being controlled by a valve and manipulated by a lever c, and in the control of this valve lies the whole manipulation of the tip. 1 This description is taken from a paper read by Mr John M‘Connochie before the Inst. Meeh. Eng. See Proceedings Inst. Meeh. Eng., August 1874, pages 125 to 130.