US 4,175,333 A · Magnetic compass

Abstract

A magnetic compass has been devised which is of the type having a pivot point displaced above the plane of the permanent magnets so that the distance of displacement of the pivot point with respect to the center of force will reduce the tilt angle or tipping otherwise caused by changes in latitude when the compass is to be operated in different parts of the world and a spherical needle bearing can be employed at the pivot point as a result of the increased pendular effect achieved by displacing the pivot point above the magnets. The need for a lift assembly to cushion the pivot point is eliminated while providing for an extremely rugged and versatile magnetic compass which will serve as a light, portable pocket transit capable of measuring horizontal and vertical angles as well as being used as a prismatic compass, level, clinometer, plumb or alidade.

Claims6

Dependent claims

A magnetic compass comprising in combination:

an annular body having a bottom wall;
an upstanding pivot member including a pivot pin having a spherical end surface at its upper end, said pivot pin being centrally located to project upwardly from said bottom wall;
a needle assembly mounted on said pivot member including a centrally located pivot mount provided with an axially extending pin-receiving bore therein terminating in a downwardly facing concave seat at the upper end of sid pivot mount, said concave surface resting upon the upper spherical end surface of said pivot pin, pointer arms extending radially in diametrically opposite directions from a location on said pivot mount vertically spaced substantially beneath said concave seat, and magnets disposed beneath said pointer arms;
and
an azimuth ring disposed in outer spaced concentric relation to said pivot mount.

2 more elements

Dependencies are inferred from the claim text.

Magnetic compass

Life of this patent

Magnetic compass

Life of this patent

Abstract

Claims6