Variable speed reciprocating lever drive mechanism

In a bicycle of the type having a frame, a steerable wheel mounted at the front of the frame, a driven wheel having a hub journalled at the rear of the frame, and a seat for a rider mounted at the top of the frame, an improved variable speed pedal driven mechanism comprising:

• a pair of rotatable drive members mounted one on each side of and concentrically with the hub of the driven wheel for rotation with respect to the frame;
• a pair of undirectional torque transmitting means connected one between each driving member and the hub of the driven wheel for transmitting torque only in the forward direction from the driving member to the driven wheel;
• a pair of elongated lever arms each pivotally mounted near its rear end to the frame, one on each side of and adjacent to the hub of the driven wheel, for reciprocal rotation within a predetermined angular sector having upper and lower limits respectively above and below a horizontal line extending forwardly from the pivot axis of the lever arm;
• a pair of pedal means attached one to each lever arm near its forward end for receiving driving forces exerted downwardly by the feet of a rider seated on the bicycle;
• a pair of first attachment means connected one to each lever arm intermediate the respective pedal means and pivot axis;
• a pair of second attachment means located one on each side of the frame above the upper limit of the predetermined angular sector of reciprocal rotation;
• means for selectively changing the location of the second pair of attachment means with respect to the frame so as to vary between predetermined limits the angle between each lever arm and a line between the corresponding first and second attachment means for a given position of the lever arm;
• a pair of idler wheels rotatably mounted respectively at one pair of said first and second attachment means;
• a pair of elongated flexible tension members, each tension member attached at one end to a respective one of the other pair of said first and second attachment means and leading therefrom around the corresponding idler wheel and thence over and around at least a portion of the circumference of the corresponding driving member in non-slip relation thereto, whereby downward rotation of the corresponding lever arm in response to a driving force exerted by a foot of the rider on the pedal thereof causes the tension member to exert a pull tangential to the corresponding driving member to rotate said driving member in the forward direction, the driving member in turn rotating the driven wheel in the forward direction through the unidirectional torque transmitting means, wherein the improvement comprises:
• an arm pivotally attached at one end to a predetermined point on the lever arm intermediate the ends of the lever arm and having the first attachment means located at its other end and
• a drag link having one end pivotally attached to the arm at a point spaced from the one end of the arm, the drag link extending approximately parallel to the lever arm and having its other end pivotally attached to the frame one of the predetermined limits of movement of the means for selectively changing the location of the second attachment means so that the first attachment means describes an arc approximately centered at the location of said predetermined limit in response to oscillation of the lever arm within the predetermined angular sector, whereby the distance between the first and second attachment means remains substantially constant for all positions of the lever arm within said angular sector when the second attachment means is located at said limit position.

In a bicycle of the type having a frame, a steerable wheel mounted at the front of the frame, a driven wheel having a hub journalled at the rear of the frame, a seat for a rider mounted at the top of the frame, and a variable speed pedal drive mechanism including

• a pair of rotatable drive members mounted one on each side of and concentrically with the hub of the driven wheel for rotation with respect to the frame;
• a pair of unidirectional torque transmitting means connected one between each driving member and the hub of the driven wheel for transmitting torque only in the forward direction from the driving member to the driven wheel;
• a pair of elongated lever arms each pivotally mounted near its rear end to the frame, one on each side of and adjacent to the hub of the driven wheel, for reciprocal rotation within a predetermined angular sector having upper and lower limits respectively above and below a horizontal line extending forwardly from the pivot axis of the lever arm;
• a pair of pedal means attached one to each lever arm near its forward end for receiving driving forces exerted downwardly by the feet of a rider seated on the bicycle;
• a pair of first attachment means connected one to each lever arm intermediate the respective pedal means and pivot axis;
• a pair of second attachment means located one on each side of the frame above the upper limit of the predetermined angular sector of reciprocal rotation;
• means for selectively changing the location of the second pair of attachment means with respect to the frame so as to vary between predetermined limits the angle between each lever arm and a line between the corresponding first and second attachment means for a given position of the lever arm;
• a pair of idler wheels rotatably mounted respectively at one pair of said first and second attachment means;
• a pair of elongated flexible tension members, each tension member attached at one end to a respectivie one of the other pair of said first and second attachment means and leading therefrom around the corresponding idler wheel and thence over and around at least a portion of the circumference of the corresponding driving member in non-slip relation thereto, whereby downward rotation of the corresponding lever arm in response to a driving force exerted by a foot of the rider on the pedal thereof causes the tension member to exert a pull tangential to the corresponding driving member to rotate said driving member in the forward direction, the driving member in turn rotating the driven wheel in the forward direction through the unidirectional torque transmitting means;
• and
• means for disengaging the connections between the rotary drive members and the hub of the driven wheel when the driven wheel is rotated backwards with respect to the frame,
• wherein the means for disengaging the connections between the rotary drive members and the hub of the driven wheel comprises:
• shaft means fixed concentrically to the hub of the driven wheel and extending outboard from each side thereof for supporting the pair of unidirectional torque transmitting means, one on each side of the hub, for both rotation and axial translation with respect thereto;
• means for interconnecting said shaft means and each unidirectional torque transmitting means for sliding each unidirectional torque transmitting means axially inboard into contact with the corresponding side of the driven wheel hub when the driven wheel rotates in the forward direction and for sliding each torque transmitting means axially outboard out of contact with the corresponding side of the driven wheel hub when the driven wheel rotates in the backward direction with respect to the frame, the unidirectional torque transmitting means rotating freely on said shaft means when out of contact with the corresponding side of the hub;
• and
• mating engagement means on the contact surfaces of the hub and respective unidirectional torque transmitting means for transmitting torque to the hub in the forward rotational direction when the unidirectional torque transmitting means are in contact with the corresponding sides of the hub.