Abstract: An improved spring-biased knockout pin apparatus for use in an impact extrusion press provides for initial pin position adjustment and subsequent spring preload adjustment without affecting the preset pin position. Methods are included.

Abstract: Means for conjointly mounting center members of dissimilar metals for stable concentric rotation about a theodolite spindle comprises a plurality of radially-extending guide grooves on one of the members disposed regularly about the axis of the spindle, and a like plurality of support elements affixed to another of the center members and similarly disposed about the spindle axis to seat respectively in the guide grooves. The support elements being thus limited by the guide grooves to precise radial movement, any dissimilar thermal expansions of the center members result in relative movement between them which is concentric with the spindle axis.

Abstract: A low-profile theodolite leveling means comprises a tribrach assembly including three separate platforms of which the second is mounted upon the first by means of a pair of pivot elements which establish a first fixed axis of tilt of the second platform, and the third is similarly mounted on the second by means of a pair of pivots which likewise establish a second fixed axis of tilt, orthogonal to the first axis, for the third platform. Located in use between a tripod head and the base of a theodolite geodetic instrument, the tribrach assembly provides means for tilting the theodolite instrument with respect to independent planes defined by the orthogonally disposed axes of tilt and respective adjustment screw members.

Abstract: Means for centering a reticle on the optical axis of a telescope comprises, within the telescope body, a split collar tapped to accommodate two pairs of diametrically opposed adjustment screws which bear upon rectilinear surfaces of a centrally located reticle mount. The arrangement provides a dust-proof seal for the telescope interior and ensures against stresses tending toward reticle misalignment.

Abstract: Azimuth and elevation adjustments in a geodetic instrument are provided by systems which include coaxial locking and two-speed adjustment control knobs. In each such system, the control knobs are accessible at both the front and rear of the instrument to facilitate operation in either of the forward- or back-sighting mode.

Abstract: Focusing mechanism for a telescope utilized in geodetic instruments and the like comprises a pair of manually accessible ring members mounted coaxially of the line of sight axis at the eyepiece end of the telescope. Rapid image acquisition is effected by means of a first of the rings which is associated with a multiple lead screw element while fine focusing is obtained by means of the second ring member which operates a single screw thread drive for the draw tube focusing lens assembly.

Abstract: Fine adjustment of a surveying instrument telescope reference spirit level is effected by rotating the bubble vial of the level about an axis which is slightly angularly displaced from the longitudinal axis of the vial.

Abstract: Telescope elevation controls in a geodetic instrument include coaxially mounted control knobs which respectively effect positive clamping of a lever arm member to the telescope axle, and fine adjustment drive of telescope elevation. Kinematic bearing means are also provided along with telescope plumb line adjustment means capable of effecting true vertical telescope axle adjustment.

Abstract: A precise indexing detent comprises a pair of grooved members the plane groove faces of which define a polyhedron within which there may be positioned a sphere in surface contact with all such faces. A detent member comprising a spherical section is situated in close association with the grooved members to govern the positional indexing of movable apparatus parts as in a level-transit surveying instrument or drafting machine protractor head.