Patent GB-785531-A (GB)
Title: Improvements in or relating to derailleur change-speed gears
IPC: B62M9/1248
Filed: 1955-06-13
Abstract: 785,531. Chain-shift change-speed gearing. JUY, L. C. H. June 13, 1955 [June 11, 1954; Oct. 6, 1954], No. 17015/55. Class 80 (2). A chain-shift change-speed gear for a bicycle comprises a carrier lever 2, Fig. 1, mounted at one end on a bracket 1 secured to or integral with the cycle frame and supporting at its other end a chain guide carrier 4 movable at right angles to the lever, and is characterized by the position of the carrier lever 2 being adjustable with respect to the bracket 1 in a direction parallel to the direction the chain guide carrier 4 moves. with respect to the carrier lever. The carrier lever 2, which is hollow, is mounted pivotally on a pin 3, Fig. 3, by means of a bush 6 rotatably but axially fixed thereon. A lug 61 on the bush engages a plate 8 and a screw 7 in the end of the carrier lever 2 locks the bush and lever &c. together when the desired axial adjustment with respect to the pin 3 has been made. A spring 9 biases the carrier lever 2 rearwardly of the bicycle to tension the chain. Change of ratio is effected by movement of a cable 12 having its end connected to a selector member 13, Fig. 4, slidably mounted in a hollow part of the carrier lever 2. A small chain &c. 14, also secured to the selector member 13, is connected to a member effecting the reciprocation of the chain guide carrier 4 to change the ratio. A transverse tongue 13<SP>1</SP> on the selector member is held by a small bar 15 engaged in one of a series of notches 2<SP>2</SP> in the carrier lever and limiting the amount of movement of the selector member; which movement can be adjusted according to whether there are three, four or five sprockets c &c. on the rear hub of the bicycle. The mechanism mounted in the hollow carrier lever 2 is protected by a cover plate 16. In a modification, a hollow carrier lever 22, Fig. 9, is mounted on a pivot pin 18, Fig. 11, by means of a bush 20 within which is a spring 21 biasing the carrier lever rearwardly of the bicycle to tension the chain. The amount through which the carrier lever can be pivoted is limited in both directions by a stop. The upper end of the carrier lever is formed so as to constitute a split collar which is clamped in a desired axial position on the bush 20 by a hollow screw 23 through which passes the control cable 12. The control cable is attached to a selector member 24 slidable within the carrier lever 22 and connected by a chain 14, passing round a roller 30, to a mounting member 25 telescoping within a sleeve 22<SP>2</SP> at the lower end of the carrier lever and supporting the chain guide carrier 4. A spring 27 surrounds the mounting member 25 and serves both to bias the mounting member &c. against the pull of the control cable 12 and also to impart a torsionally bias to the chain guide carrier 4 about the axis of the mounting member, thus assisting in tensioning the driving chain. The inner end of the spring 27 is secured to a pulley 28 rotated by movement of a cable 29 to adjust the tension in the spring 27. The cord 29 may either be operated simultaneously with the control cable 12, or may be operated separately to provide independent adjustment of chain tension. As before, the amount of movement of the selector member 24 may be adjusted according to the number of sprockets on the rear wheel hub of the bicycle. In this case, a lateral shoulder 24<SP>3</SP> on the selector member abuts a stop formed by the head 31<SP>1</SP>, Fig. 12, of a screw sliding in a slot 22<SP>3</SP> in a side wall of the hollow carrier lever 22 and also passes through a plate 32 sliding on and masking the slot. A nut 33 locks the screw in a selected position. A pointer 32<SP>1</SP>, Fig. 9, on the plate 32 slides over a scale on a cover plate 34 fitted to the front of the hollow carrier lever 22. In a simplified construction, Figs. 15, 16 (not shown), the carrier lever 22 is fitted in a predetermined angular position and is not spring biased to tension the driving chain. In a further, similar, modification, Figs. 18, 19 (also not shown), the pivot pin 18 is replaced with a hexagonally shaped pin to which the carrier lever is directly attached. Specification 785,532 is referred to.