The Mechanical Handling and Storing of Material

COAL TIPS OR HOISTS 559 sidings for the full as well as for the empty trucks, and by the way in which they run to and from the tips by the incline of the rails. The rails for the full trucks are on the ground level, whilst those for the empties are raised on staiths whereby they are entirely out of each other’s way, and the use of turntables is dispensed with. The rails c approaching the tips can accommodate 2,560 full trucks, and the network of lines e supplying the former can accommodate an additional 9,120 trucks, so that nearly 11,700 full trucks with 117,000 tons of coal can be in waiting for the seven tips. When the loading is in full swing the seven tips can dispose of 50,000 tons per day into the ships. In addition to this there is a further tip b in the Humber for bunkering the steamers without having to enter the dock, which is likewise served by separate lines of rails d in a similar manner raised on staiths. Finally there is the movable tip a1 in a line with the other six stationary ones. This portable tip is served by an elevated line of rails of about 100 yds. in length, which is about equal to the travel of the tip and parallel with it. The tips themselves are on the same principle as those at Cardiff and most other British ports, hydraulically driven; so it appears that the efforts made in some quarters to introduce electrically driven tips have failed to demonstrate their superiority, or this latest installation would probably not have been driven hydraulically. In general appearance these tips are so similar to a number of those already illustrated, that it would be superfluous to give illustrations of them. The hydraulic system, which had its birth in this country, is undoubtedly generally preferred for manipulating this class of machinery, in spite of the efforts made on the Continent to drive such appliances electrically, and surprise was expressed there that such a modern installation as that of Immingham should be hydraulically driven. The prejudice against this system on the Continent has probably in part to be accounted for by the colder climate there, and the difficulty of preventing the freezing of the mains, etc. Apart from climatic influences the balance of advantages seems in favour of the hydraulic over the electrically driven tip. In the first instance hydraulic tips are less expensive in first cost, they are far less complicated and can be attended by unskilled men, which would be hazardous with electricity. With regard to the question of economy, it may appear at a casual glance that electric motive power can be more economically adjusted to the work, but if we take into account that the load of the tip is in most cases the same, the lack of accommodation in hydraulic power to varying loads does not enter into the calculation, and when the load varies, as on the Clyde and in other docks, multiple rams are now employed, so that on account of economy no advantage can be claimed for electricity, provided always that a sufficient number of hydraulical appliances are to be served from the same mains to warrant the installation of an up-to-date plant. In order to meet further developments in the size of the ships of the future, the new hoists have been provided with a greater lift, and in all probability, with one exception, these tips are the highest yet constructed, the range being 70 ft. above the rail level, except in one in which it is only 56 ft. The wagon at this height is tipped at an angle of 45°. The tips deal with end-tip or bottom-door wagons of a gross weight of 30 tons, the dimensions of the wagons provided for being 25 ft. long over the buffers, 8 ft. 3 in. wide, and 8 ft. 8 in. high. The full wagons are drawn on to the cradle at the quay level and empties are run off on an overhead viaduct. There has also been a general advance in the speed at which these tips operate, and 180 ft. per minute is the rate that has been adopted with a pressure of 300 lb. per square inch on the accumulators at the power house. The hoists are double-powered, being capable of dealing with wagons of either 30 or 20 tons’ weight, including contents.