Patent GB-343612-A (GB)
Title: Improvements relating to chain transmission gearing
IPC: F16H7/08
Filed: 1929-11-27
Abstract: 343,612. Chain gearing. RENOLD, Ltd., H., Burnage Works, Didsbury, Manchester, and McMILLAN, K. D., 2, Crown Mansions, North Gardner Street, Glasgow. Nov. 27, 1929, No. 36384. [Class 80 (i).] Tensioning -arrangements.-In chain gearing, used for example in driving the cam shaft of an internal-combustion engine, two movable jockeywheels engaging the same outer or inner side of the chain are controllable in such manner that the chain tension may be varied without altering the phase relation between the driving and driven chain-wheels and that the phase relation may be changed with or without alteration of the chain tension. The phases of one or both of two driven wheels may be similarly adjusted relatively to that of the driving-wheel. The chain 16, Fig. 1, is engaged by jockey-wheels 18 movably supported in a carrier 20. When the wheels are moved towards each other in the carrier, the chain tension is adjusted without alteration of the phase relation of the wheels 10, 14, whereas if the carrier is moved in the direction of its length, the phase relation is changed, the chain tension being, however, changed simultaneously. Adjustment of two similar driven wheels replacing the driven wheel 12 may be simultaneously effected by similar means, or in a modification, Fig. 3, controlled adjustment of one 13 of two driven wheels 12, 13 only may be required that of the second wheel 12 being immaterial. If the wheels 18 are arranged closely adjacent to the driven wheel 12 as shown in Fig. 4, it is found that constant tension of the chain may be maintained while the phase relation of the wheels 10, 12 is changed, by moving the carrier 26 parallel to itself so that any point therein traverses a substantially parabolic path 22. The central portion of that path approximates closely to a circle, so that the carrier may be pivoted on a pair of parallel equal links 24 turning on centres 22 and adjusted by a worm 40 engaging a toothed sector 38 secured to one of the links. The chain tension may be adjusted, without affecting the phase relation, by rotation of a screwed rod 32 engaging the slidable brackets 30 carrying the wheels 18. In an alternative method of obtaining similar results with two driven wheels 12, 13, Fig. 6, the wheels 18 are so arranged that the chain lengths connecting them with the wheels 12, 13 lie substantially along arcs of a circle 48 with centre at the axis of the driving- wheel 10. The carrier 26 is secured upon a toothed bracket 44 which is adjusted upon a fixed surface 45, concentric with the circle 48, by a worm 52. In applying the same device to the arrangement shown in Fig. 3, the chain lengths connecting the wheels 18 with the wheels 10, 12 are concentric with the centre of the driven wheel 13. Two pairs of jockey-wheels 54, 56, Fig. 7, may be so arranged that their interconnecting chain lengths are concentric with the wheel 12, adjustment of the jockey-wheels 54 together or oppositely providing for phase and tension adjustments, respectively, or the chain lengths may centre about the wheel 10, when the wheels 56 are made adjustable. When slight adjustment only is required, the interconnecting chain lengths and the movements of the wheels may be perpendicular to the line joining the centres of the wheels 10, 12. According to the Provisional Specification, the jockeywheels may be moved together along the line joining the main wheel axes, and they may he mounted on pivoted arms.