Abstract: A locking structure for a spring-loaded, pushbutton pin coupler, the inveon prevents inadvertent or accidental depression of a "button latch" pin which can result in an uncoupled joint. The present locking structure cooperates with a pushbutton pin connector such as is commonly used on collapsible or extendible arms or legs. According to the invention, a conventional button latch pin is provided with a locking plate at its inner end, rotation of the pin after coupling of joint with the pin causes the locking plate to also rotate into engagement with a fixed pin element carried by the structure coupled by the pin, thereby preventing displacement of the pin from the locked position.

Abstract: A method and apparatus for cutting ice core specimens from a block or sheet f ice, the invention provides swivel cutter elements mounted on the cutter head of an ice coring auger. The swivel cutters each swing into an outwardly extending position against the force of a retracting spring on contact with ice to be cut, the outward movement of the cutters being due to reaction forces acting on the cutters caused by contact with the ice. A core specimen is thereby cut to a desired depth in the ice and advancement of the coring auger is then discontinued although rotation of the auger is continued. While auger rotation continues, each swivel cutter moves inwardly under the force of the retracting spring once the reactive forces caused by advancement of the auger into the ice no longer act on the cutters.