In building construction, concrete is usually hoisted in automatic dumping buckets. The bucket is designed to slide up and down a light framework of timber, as shown in Fig. 138, and to dump automatically when it reaches the proper place to dump. The dumping of the buckets is accomplished by the bucket pitching forward at the point where the front guide in the hoisting tower is cut off. The bucket rights itself again automatically as soon as it begins to descend. These buckets are often used for hoisting sand and stone as well as concrete. The capacity of these buckets varies from 10 cubic feet to 40 cubic feet. Fig. 139 shows a Ransome bucket which has been satisfactorily used for this purpose.