Abstract: A single-edge drill for forming a deep hole is provided which includes a body and a shank. The body has a single chip discharge groove in the outer periphery thereof, and includes a small-diameter portion, and a large-diameter portion having coolant delivery grooves in the outer periphery thereof. The body has a core thickness at the distal end portion of the large-diameter portion. At the other portion of the body, the groove bottom of the chip discharge groove is located beyond the rotation center of the drill such that the body has no core thickness, and when taken perpendicularly to the axial direction of the drill, the cross section of the body has a crescent shape. When a hole is formed with the drill, a supply path for coolant liquid is defined between the outer peripheral surface of the small-diameter portion and the radially inner surface of the hole.

Abstract: A cylinder lock includes elongated elliptical-shaped accommodation holes for accommodating auxiliary tumblers formed on an inner cylinder, and a set/reset member which is capable of freely sliding in the inner cylinder and which is pushed by two control members each having a respective stroke length, so that the auxiliary tumblers are interposed between upper tumblers and lower tumbler and moved aside from between the upper and lower tumblers, thereby enabling changing of keys for locking and unlocking the cylinder lock. Minutely, for the setting operation, the set/reset member is pushed into by a short stroke to cause the auxiliary tumblers to be accommodated into the accommodation holes and moved along the accommodation holes and held there. For the reset operation, the set/reset member is pushed into by along stroke to move the auxiliary tumblers to the side of the upper tumbler bores of the outer cylinder.