Abstract: A retaining arrangement is provided for retaining a bearing around a stub shaft having a machined cavity and which includes a ring forming a stop for the bearing nut and a locking piece.

Abstract: A mechanical support system for printed circuit boards comprising n identical elementary sub-assemblies assembled together, n being any positive integer, each sub-assembly comprising a moulded plastics mounting plate having fixed on one of its surfaces means by sliding cooperating complementary fixing devices on one of the two surfaces of m printed circuit boards so that the m printed circuit boards are fixed side by side on one surface of said mounting plate, the number m lying between one and four. M connectors for the "high-level" signals are each integral respectively with one of the m printed circuit boards, each connector comprising p male connections which plug into p female connections disposed in p of four holes in said mounting plate, said female connections being crimped on output wires, the number p lying between one and four; and a connector for the "low-level" signals snap fitting into anchor clips forming a part of said mounting plate.

Abstract: In the representative embodiment of the present invention disclosed herein, this new and improved perforating apparatus includes a unique elongated carrier strip of a ductile steel carrying encapsulated shaped explosive charges having their forward ends fitted and snugly secured against the concave rear face of the strip by means of externally-threaded axial projections respectively threaded into tapped charge-mounting holes closely spaced along the carrier. The forward face of the carrier strip and the rear portions of the capsules are complementally shaped for accommodation within a given size of well bore piping thereby allowing the largest-possible mass of explosive to be disposed in each capsule.