| 摘要 |
1373757 Vibrators CEMENT & CONCRETE ASSOCIATION 29 Oct 1971 [7 Nov 1970] 53082/70 Heading F2X A rotary vibrator includes a rotatable shaft 10 carrying at least one eccentric weight 17 so mounted as to be displaceable radially of the shaft under the action of centrifugal force to an extent which is a function of the rotational speed of the shaft. A sleeve 11 is removably secured to the shaft 10 in any angular position, as by means of a fixing screw 12, and is apertured at 13 to permit the extension therethrough of the shank of a headed pin 14. The weight 17 is in the form of a U-shaped member, the base 19 of which is centrally apertured and carries an annular bush 20 through which the shank of the pin 14 extends. A compression spring 22 surrounds the pin 14, extending between a washer 21 adjacent the bush 20 and a nut 23 on the end of a screw-threaded length 15 of the pin. Rotation of the shaft 10 causes the weight 17 to be displaced radially outwardly against the action of the spring 22, the degree of eccentricity of the weight increasing in proportion to the speed of rotation of the shaft. A number of the weights 17 may be mounted on the shaft 10, their relative angular positions about the shaft being adjustable. A vibrator of this construction is particularly suitable for use with apparatus as described in Specification 1,324,353 for forming grooves in the surface of laid plastic concrete. |
