Fig. 68
Fig. 69
The cases in which the pulleys are mounted in the cheaper grades are made of cast-iron, while in the better grades they are made of stamped metal. High-grade pulleys constructed of stamped metal are also provided; these are put together either by riveting the two faces of the pulley or by electrically welding them. The construction of a built-up steel pulley is illustrated in [Fig. 67]. The cases enclosing the pulleys are made of cast-iron, as illustrated in [Fig. 68 (a)], or they are constructed of stamped metal, as shown at (b). The ends of the facing of the case are made square, rounded, or auger-shaped, and are finished either rough, polished, or lacquered, or are faced with brass or bronze of any finish desired. The pulleys illustrated in [Fig. 69 (a)] are so constructed that the mortise in the frame may be readily formed by a special boring machine carrying three or four bits. This machine bores holes of a size to fit the several cylindrical portions of the stamped-metal case, as at a, a, a diagram of the mortising in the frame being illustrated at (b).
Fig. 70
The better grades of pulleys may be procured with semi-steel, brass, or bronze wheels, and with plain axles or with ball or roller bearings. In the cheaper grades of sash pulleys, the axles are formed of common wire, while in the better grades they are made of either steel or gun metal ⅜ inch in diameter. In the best pulleys, the wheels are turned, to insure smoothness of motion, and are made with grooves for cord, ribbon, or chain. All steel pulleys built up as illustrated in [Fig. 67] are of recent invention; they run smoothly, and are very easily applied. These pulleys are also made with ball or roller bearings, and may be obtained at a reasonable price.
