Abstract: An electric sparking drill and a method for using the same to drill a hole in a workpiece where at least one of a voltage applied to an electrode, the conductivity of a liquid applied between the electrode and the workpiece during drilling, and a gap between the electrode and the workpiece are controlled to create the desired hole in the workpiece. The electric sparking drill and a method for using the same to drill a hole in a workpiece also improve the hole operation and/or the quality of the hole made by operating at the arcing voltage, including a touch stop function, including a sacrificial electrode, and/or including a guide member function.

Abstract: A transmission-roller supporting mechanism on a transmission apparatus of a wedge roller type is provided with: an input roller; an output ring; three transmission rollers in an unequally-spaced space generated between the input roller and the output ring; and a support roller. At least one of the three transmission rollers is not fixed in position and is regarded as a movable roller supported by the support roller with its position fixed or movable. The rollers become out of contact with each other by moving the position of the support roller. The transmission of torque is cut off by moving the movable roller by the support roller. Alternatively, two transmission rollers are supported by the support roller. The two movable rollers select and play the roles of a fixed roller and a wedge roller, which causes the transmission of two-way torque.

Abstract: A rolling friction transmission apparatus of a wedge roller type is provided with: a rolling-surface-shaft; a ring; and three transmission rollers in an unequally-spaced space generated between the rolling-surface-shaft and the ring. The two of the three transmission rollers are fixed, and the rest is used as a wedge roller supported with its axis rotatable. The wedge roller is placed at a spatial position where the unequally-spaced space is wider than in the middle of the spatial position where the unequally-spaced space is at the widest and the spatial position where the unequally-spaced space is the narrowest. Friction forces generated by torque on the contact surfaces among the rolling-surface-shaft, the ring, and the transmission rollers cause large normal forces on the contact surfaces.