Sellers' Bending Bolls.—Fig. 3 shows a set of vertical bending rolls. built by William Sellers & of Philadelphia, which are capable of bending a steel plate 10 ft. wide, 11 in. thick. The bending roll, 18 in. diameter, and the two side rolls, 15 in. diameter, are carried in heavy plate housings, and so united as to embody great strength, and at the same time leave the front of the machine unobstructed for the free curvature of the plate. All three rolls are driven by a pair of independent reversing engines. The bending roll is the prin cipal driving roll, and the side rolls are adjustable to and from the bending roll by another pair of independent engines, controlled by convenient levers, and so arranged that the two ends of the rolls may be adjusted together or independently in either direction. The driving wheels at the bottom of the side rolls are of steel, while the bending roll carries at its upper end a spur-gear wheel over 5 ft. in diameter, and about 4 in. pitch by 11 in. face, driven by a steel pinion. The bending roll, with its upper bearing and driving wheel, can be with drawn by an overhead crane for the removal of flues. Hitherto the problem of driving all the rolls at the same peripheral speed has been embarrassed by the calenderiug action developed in the passage of a curved plate. To avoid this action, and at the same time
relieve the driving gear of unnecessary strain, there is provided in the train of gearing for the side rolls a positive clutch with sufficient lost motion to allow for the maximum effect of ealendering. The work of driving the plate through the rolls is thus thrown chiefly on the gearing, which drives the middle roll, and although the pinions on the side roll are thus relieved of the work of driving, they are always in readiness to assist, should the friction of the middle roll on the plate be insufficient to carry it through.
the Niles Plate-straightening Mochine, shown in Fig. 4, is designed for straightening plate iron for boilers, tanks, safes, etc. It has seven rolls arranged in two tiers—four rolls . _ in the upper tier, and three in the lower. The lower rolls are driven by steel pinions. The upper series of four rolls are adjustable vertically to suit the thickness of sheet to be straight ened. Indexes are provided for setting these rolls. The outer rolls of this series are adjustable independently ; the inner rolls are raised or lowered together, and the entire four rolls are also arranged so that, after being once set, they may all be adjusted at the same time without disturbing their relative positions.