| 摘要 |
<p>An elongated cylindrical member (1) such as an axle, a bolt, sutd, rivet, supporting column, etc., has a crack detector for the in situ detection and indication of cracks therein. The member (1) is generally solid and includes a cavity (9) extending inwardly from at least one end of the member (1) and terminating in a bottom surface (13) of the cavity. A plurality of holes (51) extends inwardly from the bottom surface (13) of the cavity and are disposed in circular array around the bottom surface (13) of the cavity and adjacent to the periphery of the member (1). A ring (15) is disposed in the cavity (9), the bottom surface (19) of the ring (15) being spaced from the bottom surface (13) of the cavity to define a chamber (23) therebetween. An opening (25) extends through the ring (15) from the top surface (17) to the bottom surface (19) thereof, and valve means (27) are inserted in the opening (25) to permit the introduction of gas under pressure into the chamber (23) and into the holes (51). When a crack develops in the member (1) and intersects one of the holes (51) the gas under pressure will escape through the crack from the chamber (23). Electrical contacts (39, 40, 41) determine whether the gas has escaped from the chamber and holes to thereby detect the crack, one contact (39) being on a sliding body (28) biased by a spring (33) against the gas pressure.</p> |
