These pulleys differ from the side pulleys in that they are made to apply above the pulley stile, which necessitates a different shape for the case. The first overhead pulley (Shull's) was patented in August, 1895, and was placed on the market early in the same year. Overhead pulleys certainly possess advantages over the side pulley, and their use will doubtless be largely extended in the near future.
Fig. 423 - Norris Sash Pulley.
The principal advantages are that they give 8 inches more play for the weights than the side pulley, and the wheel is not exposed, neither is there any opening to be seen. The face plate being mortised into the underside of the yoke, is not as conspicuous as when set in the pulley stile, and in a window fitted with shades, can hardly be seen at all. Overhead pulleys cost no more than side pulleys of the same grade. The only serious objection that has been offered to the "Shull" pulley, is that more than the usual head-room above the top of the frame is required. This has been overcome in the Queen pulley, which requires but 1¼ inches between the yoke and lintel, as shown in Fig. 421, which space is usually allowed, even when side pulleys are used. Both the Shull and Queen pulleys are made for cord, tape or chain.
Fig. 421 - Queen Over head Pulley.
Fig. 427. - Queen Mullion Frame Pulleys.
The Queen pulley is especially convenient for mullion windows, in which it is desired to do away with the pockets in the mullion, the pulleys being arranged as shown in Fig. 422, one weight balancing each sash.