Patent GB-1150943-A (GB)
Title: Improvements in or relating to pivotal supports.
IPC: F16F15/073
Filed: 1966-08-22
Abstract: 1,150,943. Spring supports. WILD HEERBRUGG A.G. 22 Aug., 1966 [30 Aug., 1965], No. 37594/66. Heading F2S. A pivotal support comprises at least one pair of spaced clamping bodies 1, 2 at least one, 2, of which is pivotable about an axis A-A of rotation, at least two elastic elements 4 and means 5 clamping each of said two elastic elements to said pair of clamping bodies with said elastic elements crossing when viewed along said axis of rotation, each of said elastic elements being flexed and clamped between said clamping bodies such that it assumes a curvature deviating from a straight line. As shown in a support of high sensitivity, for limited deflections, the fixed and rotatable bodies 1, 2 are interconnected by a pair of flexurally stiff and elastic elements 4, 4, e.g. blade or leaf springs, which have their ends clamped to the bodies 1, 2 by plates 5 so that each elastic element deviates from a straight line the forced lines of flexure being defined by an at least approximately cubical parabola and the ratio of the restoring moment to the angle of deflection, in the moment-free position of the pivotal support, being that much smaller the greater the deviation the forced lines of flexure of said elastic elements are from a straight line. The elastic elements, which can be of variable cross-section throughout their length, can be in the form of wires, helical springs, or possess other spatially curved configurations. Increasing or decreasing, the spacing of points of intersection c, d, Fig. 3, which points are obtained by projecting imaginary straight lines from the surfaces of the clamping plates 5, causes the restoring moment against rotation of the member 2 to become smaller and greater respectively. With a certain value of spacing there is no restoring moment, spacing beyond this value causing an unstable support. A piston and cylinder damping device, with stop members, can be connected between the members 1, 2. The spacing of the distance e can be made variable to give different restoring moments by making one or both spring clamping mountings on one or each member 1, 2 adjustable along the length of the member 1, or 2 to vary their distance apart (d), Fig. 5, not shown. Alternatively, the bodies 1, 2 may each be formed of two parts pivoted together and which can be forced towards, or away, from each other and locked at the desired angle. These two kinds of adjustment can be combined in a single support having the pivoted arms of the member 1 pointing downwards. When the support is located to pivot about a vertical axis the movable body (2), which carries an indicator (14), Fig. 10, not shown, is supported by a wire (11) which is connected by means of a torsion adjusting screw (13) to the free end of a leafspring (10) which is adjustable by a screw (12) and is connected to a stationary part of the mechanism. The support could be relieved, e.g. by buoyancy, magnetism &c. The null point of the indicator can be adjusted to zero by means of the screw 13. By combining two of the pivotal supports two degrees of rotational movement can be obtained, e.g. for use with a universally mounted compass. Supports can also be formed having more than two degrees of freedom. The elastic elements of each pair need not be parallel to each other, and a support could be equipped with three, or more, elastic elements.