GB616969A - Improvements in, or relating to, clocks having rotary or torsion pendulums - Google Patents

Abstract

616,969. Clocks. JORGENSEN, C. Oct. 19, 1945, No. 27457. Convention date, April 2, 1943. [Class 139] In a rotary or torsion pendulum clock the pendulum is formed by a thin torsion wire fixed at each end and carrying at its centre a bob. As shown in Fig. 1, a torsion wire 10 is clamped at its ends by members 12 and 14 mounted on springs 20 and 24 respectively carried by a fixed plate of the clockwork. The springs 20 and 24 serve to tension the wire 10 which at its centre carries a bob 16 consisting of two cylindrical portions 28 and 38 and adjustable weights carried on screws 54 and 56. At its ends the cylindrical portion 28 projects into recesses 30 and 32 in guides 34 and 36 respectively to prevent excessive horizontal displacement of the wire. The cylindrical portion 38 lies between the guides 34 and 36 and by co-operation with them prevents excessive vertical displacement of the bob 16. A rough adjustment of the pendulum can be obtained by altering the position of the weights on the screws 54, 56. For a fine adjustment, a spring 58 carried by the plate 22 and bifurcated at its outer end to engage the wire 10 is moved, by means of a screw 62, up or down, so altering the effective length of the pendulum. If desired, the spring 58 may carry a bimetallic strip bifurcated to engage the wire and arranged to bend away from or towards the adjacent suspension point according to the variation of temperature. A counterweight 42 may be provided to prevent overstress of the wire 10.