Abstract: A caliper tool mechanism is set forth. In the preferred and illustrated embodiment, a pair of opposing caliper arms are pivotally mounted on a elongate body and are recessed in elongate slots in said body. The caliper arms are retracted to a parallel position. The arms extend parallel to the elongate body and cover an elongate leaf spring. The spring has a fastened lower end affixed to the lower end of the body, and upper ends joined through moveable lengths to said caliper arms.

Abstract: A multiple arm caliper system for operation of a multiple arm caliper tool is set forth. It incorporates an elongate tool body having a motor means therein. The motor means operates a coupling rod connected to a resilient spring loading a piston within a cylinder. Within the cylinder, and extending through a transverse head defining the cylinder, individual push rods for each caliper arm extend. The push rods are forced from the chamber by fluid pressure within the chamber. Each push rod connects through suitable pivot points to an independent bell crank which is pivotally mounted to rotate each arm. Fluid pressure within the chamber is provided by the motor operating through a push rod which couples through a coil spring in the preferred embodiment to the chamber.

Abstract: This invention relates to a logging tool housing construction for use with gamma ray logging devices. The tool housing is constructed of materials designed for maximum transmission of low energy natural gamma ray energies (E=150-300 Kev). The housing material which encloses a gamma ray detector is a tubular, filament wound graphite composition and has a tubular metal sleeve for wear protection. The core and tubular metal sleeve are constructed and interconnected to meet mechanical and pressure requirements for oil well logging use.