Abstract: Hydraulic substances reinforced with high tenacity acrylonitrile (AN) fibers and a process for production thereof are provided.The high tenacity AN fibers comprise AN polymers composed mainly of AN having an intrinsic viscosity of at least 2.5 and have an X-ray crystalline orientation of at least 93%, a tensile strength of at least 10 g/d, an initial modulus of at least 180 g/d, a contrast glossiness of at least 10% and a smooth surface.Hydraulic substances reinforced with the high tenacity AN fiber are produced by uniformly dispersing in water, a hydraulic substance and the high tenacity AN fibers having applied thereto nonionic or cationic high molecular flocculants, adding anionic high molecular flocculants thereto to flocculate and adsorb cement particles onto the surface of the AN fibers and, subjecting the resulting slurry to paper-making.

Abstract: High tenacity acrylonitrile fibers are provided.The high tenacity acrylonitrile fibers comprise acrylonitrile polymers composed mainly of acrylonitrile having an intrinsic viscosity of at least 2.5 to 3.5 and having a degree of crystalline orientation measured by wide-angle X-ray diffraction within a range of 93-97%, a tensile strength of at least 10 g/d, an initial modulus of at least 180 g/d, a knot strength of 2.2 g/d and a surface smoothness.A process for production of the high tenacity acrylonitrile fiber which comprises once extruding an acrylonitrile polymer solution having an intrinsic viscosity of 2.5 to 3.5 in air or in an inert gas through a spinning nozzle, then introducing into a coagulating bath, subjecting the resulting coagulated filaments to washing with water, drawing and drying, and then drawing the filaments under a drawing tension of about 1.0 to 2.5 g/d with dry heating at about 160.degree. to about 250.degree. C.

Abstract: A means for detecting the degree of opening of claws of an electrically driven chuck in which the jaws are driven by an electric motor, is disclosed which includes a first detecting station having a. cam plate secured to the shaft of the motor and a plurality of switch means adapted for detecting the revolutions of the cam plate, a second detecting station including another a second cam plate fixed to a main power shaft of a machine tool in which said chuck is incorporated and another plurality of switch means adapted for detecting the revolutions of the another second cam plate, and a present counter adapted for emitting a signal representing the actual opening degree upon comparing two input signals delivered from the respective detecting stations.