| 摘要 |
A bicycle equipped with two, oscillatingly mounted on a joint axis (1), rear-facing levers (2) with pedals (3) and a rotary-return mechanism comprising a hub (9), bearing-placed on an axis (8), on which fixed are two freewheels (6) cooperating with levers (2) and a third chainwheel (10) transmitting the drive through the chain (13) and sprocket (14) onto the bicycle's drive wheel (15). To each of the levers (2) attached is rotatively on an axis (5) one end of one of the two chains (7) which connect these levers (2) with one of the two freewheels (6), and the other ends of these chains (7) are mutually joined with a chain (11) run on a reversible chainwheel (12). The lever (2) together with a part of the chain (7) in the upper extreme position of the pedal (3) is tangent to one of the two freewheels (6), and the second lever (2) in the bottom extreme position of the second pedal (3) is in a near-vertical position. The chain (11) and reversible chainwheel (12) ideally are lying in a vertical plane tangent to freewheels (6). The rotary-return mechanism is equipped with guards (16) protecting chains (7) against falling off the freewheels (6). In a similar way, the guard (17) protects the chain (11) against falling off the reversible wheelchain (12). The bicycle according to the invention can be equipped with both an internal and external speed changer, and it can be produced in a horizontal version.
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