Selection of Electrical Apparatus for Cranes

This paper is intended to assist crane designers and electrical engineers in mills and factories to select the proper size and kind of motor by mathematical calculation from given data, and refers particularly to the electric overhead traveling crane. The paper does not apply to heavy duty cranes which undergo regular duty cycles, nor to very small hoists such as the monorail hoist. It is hoped that at some future date someone else will write papers on these two kinds of cranes to supplement this paper. Cranes are classified here for purposes of reference within the paper. It is then shown how to calculate the power required of a motor for hoisting and how to select the particular kind of motor needed; the same information is given for bridge travel with particular reference to the live loads or accelerating loads, and also for trolley travel. The paper discusses direct-current motors separately from alternating-current motors. The calculations for each are also given separately. This is the first of a series of papers covering the field of applications of electrical equipment. This paper is on application of motors to cranes. One will follow by Mr. H. W. Eastwood on auxiliary electrical equipment such as magnetic friction brakes, overload protective panels, and limit switches. To complete the series it is planned to have the third paper on the subject of controller equipment.