Abstract: An apparatus for deciding engine-oil replacing time for an automobile. The apparatus comprises a pulse input unit into which is inputted a pulse generated during the rotation of the engine of an automobile to calculate rotational frequency of the engine on the basis of the pulse, a rotational-frequency integration unit for receiving a signal of rotational frequency of the engine output from the pulse input unit to integrate the rotational frequency of the engine, and a display unit into which is input an integrated value from the rotational-frequency integration unit and in which a degree of oil degradation on the basis of the integrated value is displayed by a display such as a LED, a liquid crystal, a 7-segment or the like.

Abstract: A device for determining swing speed of a rotatable sporting goods implement, for example human activated sporting goods i.e. a baseball bat or a golf club, wherein practice swings are undertaken seriatim. The device is comprised of a base mounted support for a rotatable screw shaft, an adjustor that is threadedly engaged with said screw shaft to enable its segmental rotation when the screw shaft is rotated, a movable member swingingly supported to the base and connected via a spring to the adjustor, which enables determination of the maximum swing speed by the tension of the spring that connects the adjustor and the movable member, causing movement of the movable member by induced centrifugal force at the time of swinging. There is also a stopper upon which the movable member may impinge to thus produce a hitting sound.

Abstract: A device for determining swing speed of rotatable implements, for example human activated sporting goods such as a bat, a tennis racquet, etc. The device comprises a mounting base, a magnetically attractable arcuately movable member in the form of a metal plate, a stopper, the movable member upon activation coming into contact with the stopper to produce a hitting sound, a support member detachably supporting the movable member, and a rotatable disk magnet likewise supported by the support member, the movable member being rotatably movable through a rotational arcuate width between the stopper and the support member. The device further comprises a counter which may be contacted by the movable member to detect numerical frequency of rotations of the movable member.