Abstract: A valve in the form of a solenoid valve includes a valve seat made of magnetic material in which a solenoid is received, and an inner diameter part of the value seat serves as a passage through which fluid flows. The valve is used for controlling an attitude assumed by an air mat. A valve assembly comprising the first-mentioned valve and an auxiliary valve may be used for the air mat.

Abstract: A valve in the form of a solenoid valve includes a valve seat made of magnetic material in which a solenoid is received, and an inner diameter part of the valve seat serves as a passage through which fluid flows. The valve is used for controlling an attitude assumbed by an air mat. A valve assembly comprising the first-mentioned valve and an auxiliary valve may be used for the air mat.

Abstract: An improved stylus, capable of following more faithfully not only horizontal and vertical vibrations but also 45.degree. vibrations, has an operative portion, for contacting the sound grooves, defined at any point thereof by the relationship that the projections of the operative portion onto the horizontal plane in respect to the axis of the stylus is part of an ellipse having a major diameter in which 0 is the angle between the horizontal plane and the line connecting the point and the center of curvature at the point, and r is the minor radius of the ellipse.

Abstract: Method and apparatus of controlling the revolving speed of a rotary body to be rotated at the predetermined number of revolution corresponding to the reference or first signal F.sub.1. The rotary body equipped with an alternating current generator which generates a frequency signal or third signal F.sub.3 in proportion to the number of revolution thereof. During operation, the signal F.sub.3 being compared with the signal F.sub.1, if the deviation of the signal F.sub.3 from the signal F.sub.1 is within tolerance, a second variable signal F.sub.2 is swept to coincide the same with the signal F.sub.3 and further to coincide with the first signal F.sub.1 while maintaining the coincidence of the second and third signals thereby to resume the number of revolution of the rotary body to that corresponding to the reference signal.

Abstract: A high speed rotary body for false-twisting comprising a tubular body in the hollow portion of which a pin element is perpendicularly fixed. The yarn to be crimped is fed into the hollow portion, looped with one turn around the pin element and delivered to a take-up bobbin. The pin element is integrally formed with three portions i.e. a smaller cylinder, a larger cylinder at one of the ends of the smaller cylinder and a truncated conical portion at the other end thereof. The intersection of the smaller and larger cylinders forms a step. When the incoming yarn portion precedes to touch the step, this portion occupies the center of the tubular body so as not to balloon during the crimping operation.

Abstract: Method and apparatus for twisting yarns for crimping purposes, wherein a yarn to be crimped is passed through a pair of opposingly rotating twisting discs in contact with circumferential faces thereof. The two twisting discs are disposed in small gap relation with each other for pressingly gripping the yarn therebetween and are rotating about the respective rotational axes which are non-parallel to each other and inclined in opposite directions relative to the length of input yarn with the respective circumferential faces turned toward a yarn gripping position from opposite sides thereof.