The Mechanical Handling and Storing of Material

DISCHARGING BY MEANS OF SKIPS AND GRABS 411 The earliest attempts to utilise on a large scale the affinity of the magnet for iron and steel are said to have been made at the Otis Works in Germany, as early as 1889, for lifting and conveying blooms, and a little later by the Illinois Steel Co. in the United States for iron plates. The pioneers of a really serviceable lifting magnet of commercial value were S. T. Wellman, who in 1895 used them for handling plates and slabs, and 1). B. Clark, the electrical engineer of the South Works of the Illinois Steel Co., who subsequently improved the design. 1 The manufacture of lifting magnets of both the Wellman and Clark types was taken up by the Electric Controller and Manufac- turing Co. (then the Electric Controller Supply Co.) about 1898. A special mag- net testing machine was designed and installed and much valuable data secured bearing on the design of the lifting magnet. Many magnets of the Clark type have been manufactured and sold and have given excellent results in the handling of smooth homogeneous material5 such as plates, blooms, and slabs ; these magnets were, however, useless for handling rough and detached material, such as pig iron, crop, ends, and scrap. A magnet which would readily lift a steel ingot weighing 10,000 lb. would not lift a single pig of Figs. 581 and 582. Grab Manipulated by Electric Motor. iron weighing 100 lb. Many were the disappointments encountered in solving the problem of overcoming the electrical and mechanical difficulties of a principle, which was practically solved when the electro-magnet was discovered in 1820 by Ampere. Success Figs. 583 and 584. Grab for Timber such as Mine Props. came slowly, but that it has been attained is proved by the fact' that the lifting magnet is to-day the greatest labour-saving device which the progress of electric engineering has achieved. The first commercially successful lifting magnet for handling pig-iron scrap and miscellaneous magnetic material was placed on the market in March 1905. This was built in two sizes known as No. 1 and No. 2 type S. Magnet. Hundreds of these magnets have since been placed in the service of the iron and steel industry, and it may 1 Compiled from an article, “ Recent Improvements in Lifting Magnets,” in the Industrial Magazine of December 1908.