Patent Publication Number: US-4147370-A

Title: Front wheel drive for a bicycle

Description:
RELATED PRIOR ART 
     
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       Clark         3,701,543                                            
       Woodruff      626,427                                              
       Huennekens    498,394                                              
       Murray        565,556                                              
       Williams      634,537                                              
       Hartley       484,712                                              
       Hendricks     3,193,305                                            
       Saxer         2,547,600                                            
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     The above mentioned prior art discloses various different front wheel drive apparatus for bicycles, wherein the handlebars are employed to induce torque into the front wheel by a pivotal action while concurrently enabling steering of the bicycle to be achieved by imparting rotational movement of the front wheel fork about a vertical axis thereof. 
     None of the above references disclose the employment of a crank driven front wheel sprocket wherein pivotal forward and rearward motion of the handlebars impart reciprocal movement into a connecting rod which in turn cranks the front sprocket, and with there being included a biasing means associated with the connecting rod which precludes the connecting rod and front sprocket coming to rest at either of the dead-center positions thereof. 
     BACKGROUND OF THE INVENTION 
     The handlebars and steering posts of bicycles must be made rugged for the reason that bicycle riders customarily exert a tremendous force thereon while pedaling in order to increase the cranking force imparted by their legs and feet into the main drive sprocket thereof. This force exerted into the handlebars represents wasted energy and it would be desirable to utilize this energy by employment of a crank system connected to chain drive the front wheel thereby achieving extra propulsion for the bicycle while requiring little or no additional effort on the part of the rider. 
     Others have proposed utilizing this wasted energy by pivotally connecting the handlebars to the steering system, thereby utilizing the pivotal motion to drive the front wheel of the bicycle. 
     The conversion of pivotal motion into rotational motion can be achieved by employment of a drive sprocket which is cranked by a connecting rod affixed to the handlebars, with the drive sprocket moving an endless chain connected to a driven sprocket affixed to the front wheel. 
     In the before described system, it is desirable to provide the driven sprocket with a one way or free-wheeling clutch assembly, thereby enabling the rider to discontinue and commence pivotal motion of the handlebars at any given time. This desirable feature, however, presents the problem of the crank and connecting rod failing to go over-the-center at the two dead-center positions of rotation, as well as sometimes causing crank reversal at each extreme length of travel of the connecting rod. Either of these situations is dangerous for the reason that when the crank is rotating to propel the bicycle in a forward direction, considerable resistance is encountered, according to the speed and power requirements of the bicycle, while hardly any resistance at all is encountered should the direction of rotation of the sprocket suddenly be reversed. Accordingly, while propelling a front wheel drive bicycle, should the crank reverse itself at either extreme limit of travel, the sudden removal of this resisting force can easily topple one from the bicycle causing potential injury to result. Therefore, it is desirable to have made available a biasing force which is placed on the connecting rod in such a manner that the rod is always biased at each extreme length of travel thereof to cause the crank to continue to turn in the appropriate direction to propel the bicycle in a forward direction. 
     SUMMARY OF THE INVENTION 
     A bicycle having a front and rear wheel drive assembly. The wheels support a main frame in such a manner that one&#39;s feet can pedal a crank sprocket which in turn drives a driven sprocket connected to the rear wheel by means of an endless chain. A handlebar assembly steers the front wheel assembly in the usual manner. According to the invention, the handlebars can additionally be pivotally moved in a forward and rearward direction in order to crank a forwardly located crank sprocket, which in turn chain drives the front wheel by means of a front driven sprocket attached thereto. 
     The forward crank sprocket is connected to the handlebars by means of a reciprocating connecting rod. Biasing means engage the connecting rod at the extreme limits of travel thereof in such a manner that the connecting rod is alternantly biased each reciprocation thereof to cause the sprocket to continue to rotate in the appropriate rotational direction as the connecting rod reaches dead-center and goes over-the-center respective to the crank sprocket. 
     In the preferred form of the invention, the biasing means is in the form of two spaced springs located on either side of the connecting rod and positioned such that one spring engages the connecting rod and biases the rod towards the other spring as the connecting rod approaches one of its extreme limits of travel, while the other spring comes in to connect with the connecting rod when the rod is moved to the other extreme limit of travel. This action prevents the crank sprocket from inadvertently coming to rest at the end of either stroke of the rod. 
     The front and rear wheel assemblies preferably are multispeed sprocket assemblies which include a one way clutch assembly such as found on the usual ten speed bicycle, for example. 
     Accordingly, a primary object of this invention is the provision of improvements in a front wheel drive assembly for a conventional bicycle. 
     Another object of the invention is the provision of apparatus by which a conventional bicycle can be modified by the incorporation of a front wheel drive assembly therewith. 
     A further object of this invention is the provision of an apparatus by which pivotal motion of bicycle handlebars impart reciprocal motion into a connecting rod, which in turn imparts rotational motion into a crank sprocket, which in turn chain drives a driven sprocket located on the front wheel of a bicycle. 
     A still further object of this invention is the provision of biasing means by which the power train of a front wheel drive of a bicycle is prevented from remaining on dead-center each 180° of rotation of the crank sprocket. 
     These and various other objects and advantages of the invention will become readily apparent to those skilled in the art upon reading the following detailed description and claims and by referring to the accompanying drawings. 
     The above objects are attained in accordance with the present invention by the provision of a combination of elements which are fabricated in a manner substantially as described in the above abstract and summary. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a bicycle made in accordance with the present invention; 
     FIG. 2 is a fragmentary, side elevational view of the front of a bicycle having a front wheel drive assembly made in accordance with the present invention; 
     FIG. 3 is a side elevational view of apparatus made in accordance with the present invention; 
     FIG. 4 is similar to FIG. 2 and discloses the apparatus of the present invention in an alternate position; and, 
     FIG. 5 is a front view of the apparatus disclosed in the foregoing figures. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 discloses a bicycle 10 having apparatus associated therewith made in accordance with the present invention. The bicycle includes a main frame 14 and a rear wheel assembly 16. The rear wheel assembly is rotated by a foot pedal actuated drive sprocket 18 in the usual manner. 
     In the various figures of the drawings, numeral 20 broadly indicates apparatus made in accordance with the present invention for imparting a driving force or torque into the front wheel 22 of the illustrated bicycle. As seen in FIGS. 2 and 4, a crank actuated front sprocket 24 has the journal thereof affixed to strut members 26 and 28. One end of member 28 is secured by the front axial bolt at numeral 30. One end of member 26 is secured to the handlebar attachment fitting as indicated by numeral 32. The other ends of members 26 and 28 are joined at 66. It will be noted that members 26 and 28, together with the front wheel fork assembly, cooperate together to jointly form a triangle. 
     As seen in FIGS. 1-5, the handlebars include members 34, 36, and 38 which have the ends thereof connected together to form a triangle. One apex of the triangle is journaled at 42 in spaced relationship to the fastener 32, although the journal 42 could be associated with the attachment point 32 should it be deemed desirable to do so. Numeral 46 indicates the handlebar grips located at another apex of the triangle. 
     Connecting rod 48 has a rod end bearing at each end thereof, with one end thereof being journaled to the crank sprocket, as indicated by the numeral 50, while the other end thereof is journaled to the remaining apex of the handlebar assembly as indicated by numeral 52. 
     Biasing means 57 preferably is in the form of two spaced apart leaf springs 56 and 58 which are connected to the U-shaped spacer 54. Spacer 54 is mounted in fixed relationship to the handlebar assembly and moves therewith in such a manner that pivotal motion of the handlebars bring alternate ones of the marginal ends of the springs into engagement with the connecting rod. 
     Endless front chain 60 forms part of the front drive assembly. The front drive sprocket is journaled at 64 to a front drive sprocket mount means located forwardly of the triangle formed by members 26 and 28. 
     Fastener 66 secures the forward ends of members 26 and 28 together and to the journal 64. Numeral 70 indicates the steering post housing by which the front forks are journaled for rotation of the front wheel assembly about a vertical axis so that the steerable front wheel can be steered by the handlebars. 
     In operation, the pivotally mounted handlebars are moved to reciprocate the connecting rod 48 between the resultant two extreme limits of travel, thereby rotating the crank sprocket. The crank sprocket accordingly reaches dead-center respective to the connecting rod each 180° of travel thereof. When the connecting rod is in either of its alternate positions, with the crank sprocket being located on dead-center, the handlebars resist being pivoted into the alternate position because the crank has no reason to go over-the-center in the absence of some compelling force such as momentum or the biasing means of this invention. 
     Where the driven sprocket is directly connected to the front wheel, the momentum of the bicycle will be effected through the drive train to carry the crank sprocket through this dead-center position; however, when a one way clutch assembly is employed between the driven sprocket and the front wheel, means must be provided by which the drive or crank sprocket is moved from this dead-center position. 
     Accordingly, biasing means 57 provides a biasing force which prevents the drive sprocket from remaining at the dead-center location while the front wheel drive is contributing to or providing all of the motive power. This is achieved by spacing springs 56 and 58 from one another and from the connecting rod when the drive sprocket is in the act of rotating between the two dead-center positions. The springs are located to contact the connecting rod with alternate ones of the springs as the drive sprocket is forced to travel over-the-center respective to its two dead-center positions which occurs during each 360° of rotation thereof. 
     As noted in FIG. 4, as the handlebars are pivoted forward and rearward, the location of the connecting rod respective to the springs is changed in such a manner that the marginal free end of one spring is brought to bear against one side of the rod, thereby biasing the rod as it approaches its dead-center position to cause a force to be effected upon the rod of a magnitude to force the crank sprocket over-the-center. During this time the other spring is spaced from the connecting rod in the illustrated manner of FIG. 3, for example. 
     As the drive sprocket approaches the other dead-center location, the marginal end of the other spring 58 bears against the opposed side of the connecting rod, thereby exerting a biasing force against the rod which biases the drive sprocket off dead-center as the drive sprocket rotates over-the-center. 
     The apparatus of the present invention can be assembled in the manner of FIG. 3 so that the combination of the present invention can be built up by using one&#39;s existing bicycle together with a rear wheel assembly and sprocket of a discarded bicycle. 
     The present invention enables one to exercise in a superior manner because his body is continually changing positions as he forces the handlebar assembly to move between the forward and rearward positions. 
     By the present invention, a free running or free wheeling assembly can be incorporated into the front wheel drive assembly since the troublesome and dangerous condition encountered when the front wheel assembly becomes locked in one of its dead-center locations has been eliminated.