Patent GB-1087559-A (GB)
Title: Bicycle drive
IPC: B62M9/08
Filed: 1964-12-21
Abstract: 1,087,559. Bicycles. M. HATTAN and W. P. GREEN. Dec. 21, 1964 [Dec. 23, 1963], No. 61787/64. Heading B7E. A bicycle comprises an elliptical chainwheel 23a engaged by an endless chain 25 or belt (not shown) engaging a circular sprocket wheel connected to the rear wheel 15, and a movable wheel assembly 46 urged by resilient means to take up slack in the chain 25 and positioned so as to displace a portion of the lower run of the chain downwardly lower than the sprocket. In an embodiment, Figs. 1-12 (only Fig. 1 shown), two elliptical chain wheels 23a, 23b and five sprocket wheels (26a), (26b), (26c), (26d), (26e) are provided. The movable wheel assembly 46 comprises chain guide wheels (52), (53) pivoted to a carrier (54) which is shiftable laterally to move the chain to different sprocket wheels, by being mounted on a parallelogram linkage (56<SP>1</SP>) controlled by a wire (65) actuatable by a manual lever 66. The carrier (54) is connected to the linkage (56<SP>1</SP>) via the resilient means (67). The chain wheel 23a is screwed at (35) to a web (31) rigidly carried on the pedal crank shaft 20, or may be integral with the web, or may be a single unapertured piece connected to the shaft 20. The chain wheel 23b is riveted or screwed at (47), or welded, to the wheel 23a. A chain guide unit 77 comprises a pair of rollers (80) engaging opposite sides of the chain 25 and mounted on a plate (83) pivoted to an arm (84) vertically swingable on a shaft (86). The shaft (86) is axially movable in a block (90) clamped to a frame member 30 of the bicycle, between two positions defined by a detent (97) and two notches (98), (99) in the shaft (86), by means of a rod 93 actuated by a manual handle (100) and having gear teeth (95) engageable with rack teeth (96) on the shaft (86), so as to move the chain between the chain wheels and to direct the chain on to a chain wheel in its own phase. The rollers (80) have radial lugs (101) to mesh with the chain, and upper and lower flanges (103) engaging the chain. The rollers (80) may be of rubber, may be without lugs (101), may have a continuous outer surface, may engage the top and bottom of the chain, or may be replaced by non-rotating guides. In another embodiment, Fig. 13 (not shown), the bicycle comprises one rear sprocket (126c) and one or more chain wheels (23c). The movable wheel assembly (50c), (52c), (53c), (54c), is secured to bicycle frame member (11c) forward of the rear wheel. In another embodiment, Figs. 14-21 (not shown), an idler sprocket wheel (111) engages the underside of the upper chain run (68d) so that the chain advances downward therefrom, and an idler sprocket or circular wheel (112) engages the underside of the lower chain run (69d) so that the chain advances downward therefrom. The wheel (111) is manually axially shiftable to move the chain between the chain wheels (23d), (23e) by actuation of a handle (114) movable upwardly to cam the wheel (111) outwardly against the tension of a spring (119) secured to the sleeve (118) on which the wheel (111) is journalled and to a clamp (116) on the frame member (116). The wheel (112) is mounted to a frame element (124) by a one-piece bracket (125) slightly larger than the element (124) so that the idler (112) may shift.