Abstract: An improved Helmholtz coil system is disclosed, which allows testing of components in a uniform DC or AC magnetic field with precise and repeatable positioning and orientation over 360 degrees of angular displacement about each of the x, y and z planes. For example, a 3-gimbaled Helmholtz coil system is disclosed, which includes a base plate that supports two coils arranged on a common axis and perpendicular to the base, and a system of three gimbals arranged in proximity to, but not necessarily located within, the magnetic field between the two coils. The gimbaled system includes an outer mount that is arranged perpendicular to the base plate and substantially intersects the center of the magnetic field. The gimbaled system includes three lockable gimbals, which can rotate on axes at right angles with respect to each other so as to allow a full 360 degrees of angular displacement in the x, y and z planes and also be locked for stabilization at any position therebetween.

Abstract: A swingable door assembly and a hinge assembly for urging the swingable door assembly to a closed position is provided. The hinge assembly comprises a torsion spring which may be an elongate torsion rod, which may be preloaded with a predetermined amount of torsion force so that the associated swingable door assembly is urged to a closed position with respect to a casing, such as a refrigerated display case. The hinge assembly includes a ratchet pin connected to the torsion spring. First and second ratchet anchors may be mounted at a predetermined distance from each other on the ratchet pin. A fixed ratchet is secured to the ratchet between the first and second ratchet anchors.