LIFTING-MAGNETS.

Star (Christchurch), Issue 9074, 1 November 1907, Page 2

LIFTING-MAGNETS.

» THE WONDERS OF ELECTRICITY.. The introduction of electro-magnets as weight-lifters has brought about an enormous saving in manual labour. An aocount^of the various types of lifting magnets now in use, illustrated with photographs of them actually in operation, appears in the September number of " Pearson's Magazine." " The idea of an electro-magnet may be easily grasped. About a century ago the discovery was made that an, iron or eteel core, fixed in a bobbin of insulated copper-wire, will attract iron or steel particles when an electric current is passed through it, and that it will release the particles so scon as the cunent is cut off. This is the principle of all the big lifting-magnets of today. Hoisting tackle, with the magnet attached, has only to be lowered upon a steel or iron load, and the switch which controlsAhe current x to be clcsed, when instantaneously the load is grasped by magnetic power, to be transported where desired, > and released by the opening of the switch. .. \ " There are many kinds of electroißagnots. The simplest sort, adapted to lifting loads with even surfaces, such as steel plates, weighing 1 from 6001 bto about three tons, cost from about £12 to £100 (according to the standard prices of one of the foremost firms engaged in making these magnets, the Electrical Company of London). More complicated* magnets^ designed for lifting such irregular loads as rough blocks of pig-iron of different shapes and sizes, cost upwards~of £300 — an outlay that is very scon Teturned to the manufacturer in the shape of wages saved. "Before the era of the lifting-mag-net there was always difficulty in raising long thin steel plates by means of slings and hooks, It involved a tedious operation. One by one the plates had to oe prised, so that the hoisting tackle could be attached, and the plates would often slip from the hooks, co that accidents were frequent. _ But nothing could be simpler than to lower the magnet on the rails with the hoisting tackle, switch on the current, and lift away, A number of plates may be lifted at one time; but the supreme beauty of the invention lies in this : the plates can be dropped where desired, separately, one by one. "To do this the operator has only to open and close the switch. As the\ ■magnetic fore© dies out the lowermost plate drops off. Then, if the switch be swiftly closed again, the magnet will retain its grip on the remaining platee. The operator must exercise same little skill in f.udsm? the time element; but a little practice soon makes him perfect nt the art, Then he will have no difficulty in T>ickihst up hfllf-a-doaen plates at a time ar><3 distributing them, one by one, in different piles, or in waiting goods trucks."