Patent GB-447614-A (GB)
Title: Improved suspension for mariners' compasses
Filed: 1934-11-21
Abstract: 447,614. Resilient mountings. DOBBIE, McINNES, & CLYDE, Ltd., and REYNOLDS, H. E., 57, Bothwell Street, Glasgow. Nov. 21, 1934, Nos. 33458 /34 and 16904/35. [Class 108 (iii)] [See also Group XX] A resilient suspension for a navigational compass, the natural period of oscillation of which is variable at will to enable resonance oscillations to be reduced, includes a member distorted by bending or torsion when the compass oscillates and means for altering the proportion of the length of the member free to distortion. In the form shown in Fig. 2, the knife edge bearing 3 for the gimbal ring 1 is hung by a chain 4 from the end of an arm 5a clamped to a bush 6 on a metal torsion ring 11 extending round the binnacle rim 9. The bush 6 rests on anti-friction rollers 6a, 6b, and the ring 11 passes between the jaws of a series of auxiliary clamps 12 which are fixed at intervals along the binnacle rim 9 and may be brought into operation at will. In a modification the bearings 3 may be suspended from diametrically opposite points of a flexible grummet ring passing through a series of clamps similar to the clamps 12. In a further modification the arms 5a may pivot on bearings fixed in the binnacle and be provided with bell-crank arms connected by chains to crank arms on vertical torsion rods. The latter are fixed at the bottoms and pass through a series of clamps which are distributed along their lengths and may be brought into operation at will. In a further modification each of the bearings 3 is fixed to the middle of a leaf spring of which the free ends are connected by vertical links to the free ends of a second leaf spring fixed at the middle to the binnacle. The points of attachment of the links to the free ends of the springs are variable. In the form shown in Fig. 9, the bearing 3 is in a bracket 80 having projections fixed to the top ends of vertical coil springs 82 threaded at their lower ends in sleeves 84 which are threaded on to screws 86 projecting from a fixed ring 87. By turning the sleeves 84 the free lengths of spring may be varied. In a modification each bearing 3 is suspended by chains from an arm which projects towards the centre of the binnacle from a bridge piece secured to the upper ends of two vertical springs carried by the binnacle. The lower ends of the springs are in threaded engagement with sleeves which may be rotated to vary the free length of spring. In a further modification each bearing 3 is hung from a plate connected to the binnacle by two opposed horizontal springs and two vertical springs, the latter being engaged by threaded sleeves whereby the free length may be varied. In a further modification each bearing 3 is hung by chains from the ends of a horizontal coil spring fixed at its centre and braced by auxiliary horizontal tension springs. The free lengths of the two arms of the main spring may be varied by rotating threaded sleeves. In the form shown in Fig. 10, a gimbal ring made in two semicircular parts 1, 1a, pivoted together at 91 is hung from the binnacle by chains 98, and the knife edge bearing 3 is hung by chain 4 from the pivot 91. A spring 94 is fixed at one end to an arm 92 depending from the part 1a and at the other end to a screw 93 non-rotatably mounted in an arm 92 depending from the part 1. A sleeve 95 is in threaded engagement with the screw 93 and the convolutions of the spring 94 and may be rotated to vary the free length of the spring.