Abstract: This invention provides a temperature responsive self-locking fastener which includes a threaded shank and a threaded mating element both having approximately equal coefficients of thermal expansion and a temperature responsive locking member having a coefficient of thermal expansion different than that of the threaded shank and the mating element. The locking member expands relative to the threaded shank and the mating element at the operating temperature to prevent disengagement of the locking fastener. At the installation temperature, the locking fastener can be easily installed or removed even after one or more cycles between the operating and the installation temperature.

Abstract: The cover retainer of the present invention is secured to the fluid end of a plunger-type high pressure pump behind a substantially circular protective cover including a shear disc surrounded by an annular outer portion, which cover is held in place by the retainer. When subjected to a compressive load by the plunger in excess of a predetermined limit, the shear disc shears from the outer portion along an arcuate boundary of reduced wall thickness between the center and outer portions and the sheared center portion is propelled by the pressure into the retainer, the interior of which is of substantially frustoconical configuration, with the base of the cone oriented substantially coaxially with respect to the shear disc. As the shear disc enters the interior of the retainer, its energy is substantially dissipated through contact between the periphery of the disc and the retainer inner wall without harm to the retainer.