GB491264A - Improved torsion spring - Google Patents

Abstract

491,264. Indiarubber springs ; spring frames for cycles. VOIGT, C. A. May 22, 1937, No. 14266. Convention date, May 23, 1936. [Class 108 (iii)] [Also in Group XXXI] A torsion spring element comprises a rubber member which is adapted to be stressed in shear by the relative movement of two pivoted members and which is bonded to the pivoted members, or to metal parts connected to these members, and is only a portion of a disc or ring. The rubber element may be constituted by a block of rubber positioned away from the pivotal axis, and such that its greatest circumferential dimension in a plane perpendicular to the pivotal axis subtends a relatively small angle at the pivotal axis. In the construction shown in Fig. 1, an arm 2 carrying a wheel 1 is secured to an axle 3 mounted in a frame member 4 by a journal bearing 5 and a roller or knife-edge bearing 6. Two blocks 9 of rubber are bonded to plates 8 secured to the frame 4 and to plates 7 non-rotatably secured to the axle 3. The plates 7 are inclined outwardly relative to the plates 8 in order that the cross-sectional area of the rubber blocks may increase with distance from the pivotal axis. Alternatively or additionally the blocks 9 may be formed of rubber of different compositions and such that its elasticity progressively increases with respect to distance from the axle 3. In a modified construction, Fig. 3, the arm 2 is rotatably mounted on a bolt 19 and the rubber blocks are secured to extension 4 of the frame and to plates 20 secured to the arm. The arm 2 may be extended beyond the bolt 19 and attached to further rubber blocks. In a further modification the bolt 19 is rotatable in the frame member 4 and is formed with a rigid extension acting as a torsion bar. Fig. 6 shows an arrangement applied to a cycle or motor cycle in which blocks 16 of rubber are secured to plates 20 attached to the rear fork 14 and to plates 21 attached to a rearward extension 17 of the frame 18 mounted on a transverse pin 15. The plates 20, 21 are inclined towards each other so that the rubber is also compressed by relative movement between the fork 14 and frame extension 17. Where necessary a number of blocks may be arranged in line parallel to the pivotal axis.