Engineering Wonders of the World
Volume III

REMARKABLE MACHINERY. 259 LEG AND BUCKET OF HULETT UNLOADER AT WORK IN THE HOLD OF A MODERN ORE-CARRYING VESSEL. traps in the bottom into main-line cars on the tracks underneath, and hauled away by the yard locomotive. In cases where the ore has to be stacked in a pile immediately to the rear of the quay, it is discharged into a second conveyor built on to the unloader, run out over the stock pile, and dumped. Apart from their huge capacity, these machines are remarkable for the method of their control. The operator steel mast just above the bucket, and descends with it into the boat. He is there- fore always in full view of his load ; and when the cargo is nearly exhausted, he can place his bucket in the most advantageous position. As the buckets are designed to hold ten tons of ore, and make more than one bite per minute, one of these machines will handle over 600 tons per hour. Four machines work- ing together have unloaded a cargo of iron ore of 7,200 tons in four and a half hours —a record that should satisfy the most exacting shipowner. These unloaders are fitted with a separate powerful motor for each motion. That for opening and closing the bucket develops 80 horse-power ; that for operating the rocker, 150 horse-power ; while that for .moving the whole machine—a weight of 900 tons—along the quay is 260 horse- power. We may note that in connection with these unloaders a special type of boat has been evolved. The boilers and engines are placed right at the stern of the vessel and the navigating bridge and Boats, crew space right forward, leaving the whole of the body free for ore. This space is ample to allow four unloaders to work in it simul- taneously. The hatch-covers are made to slide, so that all areas of the bunker space can be uncovered in turn. Moreover, the shape of the boat is such as to enable the unloader to reach all parts of the hold. In the later boats, 96 per cent, of the cargo has been un- loaded without the aid of shovellers, which is probably a record in the mechanical hand- ling of material in bulk. is carried in the Another interesting type of machine used A CAR DUMPER EMPTYING A RAILWAY ORE CAR (a) INTO A BOTTOM DUMPING CAR (ß). One wheel of A is seen, pointing upwards.