Patent GB-750929-A (GB)
Title: Improvements in and relating to derailleur variable speed gear for cycles
IPC: B62K23/06
Filed: 1953-11-16
Abstract: 750,929. Change speed gearing. FELIX, J. W. Nov. 12, 1954 [Nov. 16, 1953], No. 31767/53. Class 80(2) [Also in Group XXXI] A chain shift change - speed gear for bicycles comprises a main arm 20, 22 pivotable and axially movable on the spindle 21 of the rear wheel hub of the bicycle, a jockey sprocket 24 on the main arm engaging the underside of the chain 25, means 66, &c. for moving the main arm laterally to engage the chain with sprockets 62, 63 on the spindle 21, a tension arm 36 pivotable about the spindle 23 of the jockey sprocket 24 and carrying a jockey roller 38 supported by a pilot ban 52 sliding in a stationary guide 53 and means 39-51 co-operating with the jockey sprocket to maintain a constant tension in the chain. A chain 25 passes between two plates 26, 127 connected together to form a cage, pivotal about the axis of the jockey sprocket 24 and connected by a pivotally mounted bar 29, passing through a hole in the main arm 20, 22, which is of cranked form, to a slide 30 carried by the main arm. A plunger 66 has a groove 68 engaged by the slide 30 and is moved axially to change the ratio. The plunger 66 is biased in one direction by a spring 81 and is moved against the sring bias on actuation of a cable 78 connected to one end of a lever 74 fulcrumed at 75 on the spindle 21. If the bicycle is wheeled backwards, friction between the chain 25 and the cage 26, 27 causes the latter to be rotated clockwise, which, through bar 29 &c. disengages the slide 30 from the plunger 66 so that an attempted change of ratio by manipulation of the cable 78 cannot jam the chain. The chain 25 is tensioned by means which consists of levers 41 42, pivoted at 39, 40 on the main arm 20, connected by a spring 43 and tensioned by a spring 44 secured at one end to the lever 41 and at the other end to ratchet wheel 46 engaged by a pawl 47. The tension in the spring 44 is adjusted by a disengaging the pawl 47 from the teeth on the ratchet wheel 46. which is then turned. The long end of the arm 42 is hooked at 48 to engage a roller 49 on a link 50 comprising two parallel members connected at 51 to the tension arm 36. A link 59 is pivoted at 58 to the pilot bar 52 and at 60 to the main arm 20, 22. A skid 55 on the pilot bar 62 engages the chain 25 and prevents impact between the chain and the jockey roller 38. The link 59 &c., maintains the pilot bar 52 and skid 55 in the same planes irrespective of the varying angular positions of the main and tensioning arms. The gearing can be contained in a casing 54 forming an oil bath. The two ratio chain shift change speed gear drives a three ratio planetary gear (not further described) in the hub of the cycle wheel. The ratio of the planetary gear is selected by operation of a cable 77. The cables 78, 77 are attached to cables 90, 91, Figs. 6-9, secured to plates 110, 112 pivotable about a pin 98 in a casing 92 secured to the handle bar, &c. of the cycle. A control lever 93 is fast with a ring 94 in the casing 92, rotatable about a pivot 95. Angular movement of the lever 93 in either direction from the neutral position shown is limited by stops 96, 97 thereon engaging the pivot pin 98. A spring 99 normally holds the lever in this neutral position. Pawls 101, 102, pivoted within the ring 94, are spring biased to engage the teeth 105 of a ratchet wheel 104 rotating on the spindle 95, and are disengaged therefrom during the inoperative stroke by a fixed cam 106. Cams 107, 108 are pinned to the ratchet wheel 104 and engage rollers 109. 111 on the pivoted plates 110, 112. The cams 107, 108 are so shaped that each depression (or elevation) and return stroke of the lever 93 produces successive changes in ratio in the combined change speed gears, from the sixth ratio down to the first ratio, and vice versa. A circular cam plate 113, fast with the ratchet wheel 104, carries the numbers 1 to 6, which are visible through a window 114 in the casing 92 and indicate which ratio has been selected.