Abstract: An oscillatory actuator 1 includes a cylindrical case 2, an electromagnetic driver 3, a mover 4, a first damper 40a, and an inner guide 6a. The electromagnetic driver 3 is provided inside the case 2. The mover 4 is enabled to oscillate through driving by the electromagnetic driver 3. The first damper 40a has a plurality of arms 52a supporting the mover 4 from an inner surface of the case 2. The inner guide 6a is provided on the inner surface of the case 2 and restricts movement of the first damper 40a beyond a predetermined range. The inner guide 6a is located further toward a center of the case 2 than the first damper 40a in a direction of an oscillation axis ? of the mover 4.

Abstract: A flaw sensor for a metal pipe has an exciting coil for generating remote field eddy currents in the pipe. First and second groups of receiving coils are spaced from the exciting coil by respective distances along the axis of the pipe in a region of the generated remote field eddy currents. The first and second groups have respective pluralities of receiving coils with axes perpendicular to the pipe axis and disposed circumferentially about the pipe axis at predetermined angular increments wherein the receiving coils of the second group are staggered relative to the receiving coils of the first group. A third receiving coil is disposed coaxially with the pipe at still another distance from the exciting coil along the pipe axis but also in the region of the generated remote field eddy currents.

Abstract: In a variable speed geared motor constructed by combining an inverter motor controllable in rotational speed by inverter drive with a gear reducer, the gear reducer is of a two-stage type, and a reduction ratio i of the gear reducer is suppressed so that i.ltoreq.N holds where N stands for a maximum reduction ratio of the inverter motor at which a constant torque characteristic can be ensured. Further, in a series of variable speed geared motors each satisfying the above conditions, a common ratio R of a series of reduction ratios i of the variable speed geared motors is set to 1.2-1.5. For example, the series is set to 2, 3, 4, 5, 6, and 8.Accordingly, the geared motor can be constructed lightly in weight, compactly, and at low costs, and it can be economically used in a rotational speed region of 200-900 rpm which is an ordinary region in driving of a pump or a high-speed conveyor.

Abstract: In a motor-equipped reduction gear device with a pre-stage, two covers, which have been indispensable in the past, namely a joint cover and a pre-stage cover, are integrated into a one-body cover (130). Also, the diameter (D1) of the addendum circle of the pinion (110) mounted on the tip of the motor shaft 108 is designed to be smaller than the diameter (D2) of the portion of the motor shaft (108) which extends into the one-body cover (130). This allows the one-body cover (130) to be mounted with the pinion (110) already attached to the tip of the motor shaft (108). The one-body cover (130) can freely and easily be attached to the motor (102) and the gear box (106). As a result, the number of parts is reduced and light weight and compactness are achieved, and accuracy of the center distance and parallelism are improved because cumulative machining errors can be avoided. Furthermore, cost down and improved rigidity are achieved and the number of factors which may cause oil leakage is decreased.