The machine shown in Figs. 1, 2, and 3 has been devised by Messrs.
Junker & Ruh, of Carlsruhe, for cutting internally-toothed gear-wheels.
The progress of the work is such that the wheel is pushed toward the
tool by a piece, n, provided with a curve guide, and that the tool is
raised and separated from the wheel after a tooth has been cut, in order
to allow the wheel to revolve one division further.

The tool is placed in a support, b, which is fixed to the upright,
d, in such away that it may revolve; and this support is connected to
the frame, a, of the machine. A strong flat spring, f, constantly
presses the tool-carrier, b, toward the upright, d, as much as the
screw, g, will permit; and this pressure and the tension of the belt
draw the tool downward. The screws, g, determine the depth of the cut,
and compensate for the differences in the diameter of the tool.

[Illustration: MACHINE FOR CUTTING ANNULAR WHEELS.]

The wheels to be cut are set by pressure into a wrought iron ring, with
which they are placed in a sleeve or support, h. The connection
between the two is assured by means of a nut, c. The axle of the
support, h, is held in the upright of the carriage, k, which
receives from a piece, l, placed on the driving-shaft, n, a slow
forward motion toward the tool, and a rapid motion backward. The
trajectory curve or groove of special form of the piece, l, in which
moves the conducting roller, o, of the carriage, is not closed
everywhere on the two sides, in that the guides that limit it extend
only on the part strictly necessary. This arrangement permits of the
roller being made to leave the trajectory in order that the carriage may