3742. Stumpf, J. Feb. 17. Impact-wheels.-Relates to impact-wheels driven by steam or gas jets and provided with one or more return guide-buckets b, Fig. 3, having short steep admission arms b<1> and longer discharge arms b<2>, so that the motive fluid passes through one of the wheel buckets a, and escapes into a return bucket, which discharges it again on to the wheel. The invention consists in using double buckets a, Fig. 2, of the Pelton-wheel type and providing the wheel with double return buckets b, which may be arranged for either central or lateral jets. The return buckets may have internal ribs e and an inner wall.