One hollow is cut during each forward travel of the carriage; and, when such travel is finished, a cam-disk, p, placed on the shaft, n, lifts the tool-carrier, b, and thus draws the cutting-tool out of the hollow cut by it, so that the carriage cam can then move back without restraint. In the interim, the sleeve, h, which supports the wheel, revolves one tooth through the following arrangement: On the axis, e, of this sleeve there are two ratchet-wheels, r and s, the number of whose teeth is equal to that of the teeth to be cut in the wheel. The wheel, r, produces the rotation of the sleeve, h, and the wheel, s, keeps the shaft stationary during the operation. The two wheels are set in motion by a lever, t, or by its click, this lever being raised at the desired moment on the free extremity of the driving shaft, n, by a wedge, u. The short arm of the lever, t, engages, through its point of appropriate shape, with the teeth of the wheel, s, so as to keep this latter stationary while the tool is cutting out the interspace between the teeth. When the lever, t, is raised, this point is at first disengaged from the wheel, s; and the raising of the lever being prolonged, the button, i, places itself against the upper curve of the slot in the lever, q, and raises that likewise. q is connected with the lever, v, which revolves about the axis, e, and v carries the click, w, so that when the lever, v, is raised, the wheel, r, turns forward by one tooth. When the lever, t, is lowered, as the wedge, u, turns more, its click holds the wheel, s, stationary. This series of operations is repeated until the last interspace between the teeth has been cut, when the machine stops automatically as follows: A cam of the disk, A, which receives from the shaft, n, through cone-wheels, a motion corresponding to that of the wheels, r and s, abuts against the two-armed lever, z, and this latter then disengages the rod, y, so that the weight, G, can move the fork, B, in such a way that the belt shall pass from the fast to the loose pulley. Motion is communicated to the machine as a whole by the shaft, C, which is provided with a fast and loose pulley. As shown in the engraving, the pulley, D, moves the tool, and the pulley, E, causes the revolution of the shaft, n, through a helicoidal gearing, F. The construction of the tool carrier is represented in detail in Fig. 3. The cutting tool, F, rests on a sleeve forming part of the pulley, r1, against which it is pressed by a nut, while its position is fixed by a key. The axle, s1, of the tool is held in two boxes, in which it is fixed by screws. In order that the tool may be placed exactly in the axis of the wheel to be toothed, and that also the play produced by lateral wear of the pulley, r1, may be compensated for, two screws, r2, are arranged on the sides. All rotation of the shaft, s1, is prevented by a screw, o, which traverses the cast iron stirrup, C, and the steel axle box.