A. It is an outside gear with an eccentric crank, similar to the
Walschaert gear, but without a reversing link. The motion is reversed by
means of a reversing yoke instead of a link; the cut-off is changed in
the same manner. It uses a combination lever connected with a union link
to its cross-head arm. In case of breakdown remove the broken parts the
same as described for Walschaert gear, blocking the reversing yoke, if
necessary, in the proper position.