The Mechanical Handling and Storing of Material

524 THE MECHANICAL HANDLING OE MATERIAL trunnions 8 in. in diameter, which are placed slightly out of centre with the platform so as to give it a natural inclination to sink towards the waterside. The balancing device consists of two weights secured by iron bracings to the lower portion of the platform. The total weight of the two is 5 tons, or somewhat more than the weight of the empty truck. As soon as the load has left the truck there will be a tendency for the counter- weight to replace the platform in its original position. During the return of the platform, the hydraulic cylinder and piston are again brought into action to prevent a too quick return of the platform, and thus avoid shock. The railway trucks are specially constructed for this particular purpose, and have hinged side doors instead of the more usual end doors. The whole load of 10 tons is discharged Fig. 731. Tip at Bethune. into a shoot which is of sufficient capacity, the outlet of this shoot being so contracted as to let the coal out into the barge in a gentle and more or less uniform stream. It is generally so arranged that the same time is allowed for the coal to empty itself out of the shoot into the barge as it takes to bring back the empty truck into its original position and replace it by a full one. A number of capstans have been erected at the quay by means of which the barges can be quickly put into position for loading. One man is sufficient to operate the tip. Two such tips are now at work at Bethune, and as each is capable of dealing with twenty-five trucks of 10 tons each per hour, 5,000 tons per day of ten hours can be handled, and a speed of five wagons m ten minutes has been accomplished. These tips have the undoubted advantage that the empty trucks can never be in the way of the full ones, as all trucks, both full and empty, are moved in the same direction and on the same road. A device similar to the Bethune coal tip was erected by the Société Charbonniére,