Abstract: A bone mill has a pair of cutter units, a first cutter unit and a second cutter unit. A bone to be crushed is taken in between the first cutter unit and the second cutter unit. While passing between the first cutter unit and the second cutter unit, the bone is crushed. Each cutter unit has a plurality of disks disposed in parallel to one another at regular intervals. Each disk is provided on the periphery thereof with blades for crushing the bone. The cutter units are positioned such that the disks of the first cutter unit are fitted in the gaps between adjacent disks of the second cutter unit. Both the disks of the first cutter unit and the disks of the second cutter unit are mutually inwardly rotated. Accordingly, when a bone to be crushed is supplied between the cutter units, the bone is taken in by and between the disks of the first cutter unit and the disks of the second cutter unit, both sets of disks being mutually inwardly rotated.

Abstract: An ignition system for four cycle engines generates a first pulse when the crankshaft revolves by a first setting angle from a base position. The second pulse is generated when the crankshaft revolves to a second setting angle which is larger than the first setting by the angle difference between cylinders. The third pulse is generated at the position of a third setting angle which is between the first setting angle and the second setting angle in the position of the crankshaft when the crankshaft revolves twice. The generation of the first and second pulses is stopped or inhibited during the generation of the third pulse, allowing the first pulse to fade away.