Abstract: A fire safety transmission apparatus comprising an explosion-proof container, an adapter plate secured to the container, a cylindrical sleeve mounted to the adapter plate defining a central bore, allowing communication with the interior of the container. The sleeve bore is stepped, defining seats for a plurality of ball bearing races mounted therein. A rotatable stepped shaft having a diameter adapted to fit within the central bore rests on the ball bearing races. The shaft is connected to a motor mounted in the explosion-proof container with the spacing defined between the inner wall of the cylindrical sleeve and the outer surface of the freely rotating shaft being sized a predetermined tolerance for a predetermined length sufficient to prevent a flame from passing therethrough.

Abstract: A mine car coupling device is described which comprises a coupling pin assembly pivotally mounted so that a pin is automatically engaged into the aperture of an elongated ring shaped receiving member or tongue. The housing has sloped front guide surfaces and curved inner side walls that align the coupling receiving member or tongue in both horizontal and vertical orientation so that the pin will be affirmatively engaged in position. The coupling receiving member permits horizontal and vertical variation of the tongue member through the use of compressible rubber springs.

Abstract: A mine car coupling assembly comprising a spring biased receiving assembly having a pair of jaw members mounted about a pivot point. The forward ends of the jaw members are beveled and tapered inwardly to form a hook configuration adapted to receive and hold an arrowhead shaped male member. Each jaw member's forward end is biased toward the other jaw member's forward end by a spring assembly mounted to both of the jaw members. The tip of the arrowhead member initially engages the jaw members of the receiving assembly and overcomes the spring assembly's force, forcing the jaw members apart. When the arrowhead has entered into the receiving assembly the hook ends are urged back toward each other by the spring assembly to engage the rear surface of the arrowhead member and hold the arrowhead member in position within the receiving assembly.