To the bracket or arm b are pivoted the arms or belt guides c and d and the piece g. In the position occupied by the parts in the figure the belt for the forward or cutting stroke would be upon the loose pulley p′, and that for the quick return stroke would be upon the loose pulley p, hence the machine table would remain at rest. But suppose the rod f be moved by hand in the direction of arrow f, then g would be moved upon its pivot x, and its lug h would meet the jaw i of c, moving c in the direction of arrow a, and therefore carrying the belt from loose pulley p′ on to the driving pulley p′′, which would start the machine work table, causing it to move in the direction of arrow w until such time as the stop a meets the lug r, operating lever e and moving rod f in the direction of arrow d. This would move g, causing its lug h to meet the jaw j, which would move c from p′′ back to the position it occupies in the figure, and as the motion of g continued its shoulder at g′ would meet the shoulder or lug t of k (the latter being connected to d) and move arm d in the direction of b, and therefore carrying the crossed belt upon p, and causing the machine table to run backward, which it would do at a greater speed than during the cutting traverse, because of the overhead pulley on the countershaft being of greater diameter than that for the cutting stroke.
Fig. 1567.
It is obvious that since each belt passes from its loose pulley to the fast one, the width of the overhead or countershaft pulleys must be twice as wide as the belt, and also that to reverse the direction of pulley revolution one driving belt must be crossed; and as on the countershaft the smallest pulley is that for driving the cutting stroke, its belt is made the crossed one, so as to cause it to envelop as much of the pulley circumference as possible, and thereby increase its driving power. The arrangement of the countershaft pulleys and belts is shown in [Fig. 1567], in which s is the countershaft and n, o the fast and loose pulleys for the belt from the line shaft pulley; q′ is the pulley for operating the table on the cutting stroke (with the crossed belt), while q is the pulley for operating the table on its return stroke. The difference in the speed of the table during the two strokes is obviously in the same proportions as the diameters of pulleys q′ and q.
The feed rod, and feed screw, and rope for lifting the tool on the back stroke are operated as follows:—
Fig. 1568.
[Fig. 1568] is an end view of the mechanism viewed from the front of the machine, and [Fig. 1569] is a side view of the same.