Abstract: A pair of connector elements, one connector element having a locking arm, the other connector element having a hood for receiving the one connector element and a locking protrusion provided within the hood are locked in engagement of the locking arm with the locking protrusion when they are completely coupled with each other. When the connector elements are not used or before they are coupled with each other, a body for preventing the one connector element from being fit into the other connector element is inserted in the hood of the other connector element. The body has a locking arm to be engaged with the locking protrusion and a locking portion into which a dedicated jig for pulling out the body from the hood is to be inserted. Thus, in electrical wiring for e.g. an air bag for motor vehicles, it is prevented that when the pair of connector elements are to be coupled with each other, they are connected with a false current flowing through the one connector element and explosion happens in an inflator.

Abstract: The invention provides a method for the preparation of a pitch spinnable into pitch filaments as a precursor of carbon fibers starting from a pitch material such as coal tar and coal tar pitch. Different from the conventional procedure involving hydrogenation of the starting pitch, the starting pitch in the inventive method is first heated together with an aromatic oil, preferably, in the presence of a cracking catalyst such as silica-alumina and zeolite at 350.degree. to 500.degree. C. for 10 to 60 minutes under no pressurization with hydrogen and, after removal of insoluble materials, then heated at a temperature of 430.degree. to 600.degree. C. The thus obtained pitch for spinning has good spinnability and the carbon fibers prepared from the pitch have a unique microscopic structure and excellent physical properties exceeding by far the conventional pitch-based carbon fibers and approximating the HP-grade carbon fibers prepared from polyacrylonitrile fibers.

Abstract: A pattern for a pattern wheel used in a circular knitting machine is set by detecting a blade of the pattern wheel to actuate a tape reader which has been patterned in advance, and pushing a jack of the pattern wheel in response to the signal from said tape reader.