Patent Publication Number: US-2015072336-A1

Title: Four Bar Drive Link Simulator

Description:
TECHNICAL FIELD 
     This invention relates to a mechanical fixture which simulates a four bar link drive system for pedal driven scooters and bicycles. More particularly the simulator allows a wide range of link dimensions to be quickly evaluated for pedal performance and provides an easy way to find a set of dimensional solutions for optimal pedal performance. The simulator replicates the pedal action and accurately permits the evaluation each of the four link dimensions. 
     BACKGROUND OF THE INVENTION 
     Pedal driven bicycles have been well known in the art of man powered vehicles. The most common pedal system uses a chain driven pair of sprockets to which pedals are attached to the front drive sprocket while a chain is attached to the front drive sprocket and the rear wheel sprocket propelling the rear wheel to provide movement. This system has the pair of pedals positioned 180 degrees relative to the other, so in combination, they rotate 360 degrees about the axis of rotation of the drive sprocket; with the rider exerting maximum force on each downward motion on each pedal. This is a most simple and efficient way to move a two wheeled bicycle. 
     A more complicated, but arguably superior drive system for a bicycle or scooter has been developed utilizing a four bar link drive mechanism. The drive mechanism employs a drive sprocket attached to a bottom bracket fixed onto a bicycle or scooter frame, a crank link attached to the drive sprocket or the axle of the drive sprocket and rotationally fixed to the rotation of the drive sprocket, a coupling link attached at one end to the crank link and at an opposite end to a foot pedal, the foot pedals being pivotally attached at one end to the crank link and at an opposite end, the foot pedal is pivotally attached at an end, called the proximal hinge location of the vehicle frame forming a four bar linkage assembly wherein the distances between axis of rotations at the various attachment locations define the movement. The distance between axis of the pedal proximal hinge location attachment to the frame and the axis of the drive sprocket forms a virtual frame link F. The distance between the axis of the proximal hinge location of the pedal to the axis of the coupling link to pedal attachment defines a dimension P, the distance between pair of axis of the coupling link defines a dimension C 2  and the dimension between the pair of axis of the crank link defines a dimension C 1 . The combination of dimensions F, P, C 1  and C 2  define the four bar linkage and are critical to the performance of the foot pedals and the vehicle. This drive mechanism as described provides a reciprocating pedal action wherein the rider can exert downward pressure on each downward pedal stroke to propel the vehicle. The foot pedals are set so when one pedal is at the bottom of its stroke, the other pedal is approximately at its maximum stroke relative to the other so that the rider can provide alternating propulsion strokes with each leg. 
     This drive mechanism is described in greater detail in U.S. patent application Ser. No. 12/554,366 filed on Sep. 4, 2009 entitled “Pedal-Drive System for Manually Propelling Multi Wheeled Cycles” and Ser. No. 12/848,567 filed on Aug. 2, 2010 entitled “Improved Scooter and Pedal Drive Assembly; the entirety of each application being incorporated herein by reference. 
     The present invention does not claim this four bar linkage drive system, but rather teaches and discloses a unique simulator device capable of providing optimal solutions to the physical location and dimensions of the four bar linkage system. 
     During the development of a reciprocating pedal drive system it was discovered that the positioning of the components on a vehicle frame such as a scooter or bicycle were critical. The dimensions and relative locations of F, P, C 1  and C 2  affected how the foot pedals moved. Minor adjustments of one element affected the entire pedal performance. Selection of these dimensions was such that minor variations in manufacturing tolerances during assembly could result in poor pedal action. 
     These problems were not simply poor pedal operation, but included a linkage lock up preventing pedal movement or even pedal reversal causing the linkages to change or reverse direction. The present invention describes a device to enable quick and reliable establishment of these critical dimensions. 
     SUMMARY OF THE INVENTION 
     A four bar drive link system simulator has a frame assembly, a proximal hinge attachment bracket, a bottom bracket simulator, a pair of crank levers, a pair of coupling levers and a pair of pedal simulator levers. The frame assembly has a plurality of guide rails, including at least a proximal hinge adjustment rail, and a frame simulator rail. The proximal hinge attachment bracket is connected to the proximal hinge adjustment rail. The bottom bracket simulator is attached or otherwise connected to the frame simulator rail. The pair of crank levers is each attached at a first end to an axle having its axis of rotation in the bottom bracket assembly, one crank lever being on one side of the bottom bracket assembly, the other on the opposite side. The pair of coupling levers is each attached to an opposite second end of the crank lever. The pair of pedal simulator levers is each pivotally attached to an end of the coupling lever and to an axis of rotation of the proximal hinge attachment bracket. The relative dimensions between the axis of rotation of proximal hinge and axis of rotation of the bottom bracket are adjustable by movement along the proximal hinge guide rail or the frame simulator guide rail or a combination of both. 
     The pair of pedal simulator levers each has an adjustable coupling attachment bracket. Movement of the adjustment bracket changes the dimensional distance between axis of rotation of the proximal hinge bracket and the pivotal attachment end of the coupling lever. The pedal simulator levers also each have a pedal stroke lever angularly adjustable to change the bend angle of the pedal simulator levers. The four bar drive link system simulator may have a second bottom bracket simulator slidably mounted onto the frame simulator guide rail. The second bottom bracket simulator has an axle to which a pair of sprockets can be attached. The frame assembly further may have a rear lateral guide rail onto which an adjustable rear wheel mounting assembly for attaching a rear wheel sprocket and axle assembly is affixed wherein chain alignment of the vehicle can be simulated and adjusted by lateral movement. In a preferred embodiment, the crank lever has a moveably adjustable coupling attachment to change the crank lever length between the axis of rotation of the bottom bracket and the coupling lever attachment. The crank lever may be a spider lever for attachment onto a drive sprocket and the spider lever has the adjustable coupling attachment. Similarly, the coupling levers may have movably adjustable pedal attachments for changing the coupling lever length between the crank lever attachment and the pedal simulator attachment. 
     The invention can include A pedal assembly for us with a four bar drive system comprising: a front portion block; a front portion adjustment rod slidably attached to said front portion block; and, a rear portion block attached to said front portion adjustment rod so that the distance between the front portion block and the rear portion block can be modified. The invention can include a coupling lever having a front coupling block rotatably attached to said front portion rear block; coupling rods slidably attached to said front coupling block; and, a rear coupling block attached to said coupling rods so that the distance between the front coupling block and the rear coupling block can be modified. The invention can include a crank lever having a front crank block rotatable attached to said rear coupling block; a crank rod slidably attached to said front crank block; and, a rear crank block attached to said crank rod so that the distance between the front crank block and the rear crank block can be modified. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the present invention four bar drive link simulator. 
         FIG. 1A  is the perspective view of the four bar drive link simulator of  FIG. 1  with one pedal simulator removed to allow viewing of the crank lever and coupling lever. 
         FIG. 2  is a side plan view of the four bar drive link simulator made according to the present invention. 
         FIG. 3  is a top view of the four bar drive link simulator made according to the present invention. 
         FIGS. 4 and 4A  are exploded views of the four bar drive link simulator assembly of  FIG. 1 . 
         FIG. 5  is an end view of the four bar drive link simulator. 
         FIGS. 6 ,  6 A,  7  and  7 A are an exemplary scooter with a four bar drive link mechanism.  FIG. 6  being a perspective view,  FIG. 6A  being a top view and  FIG. 7  being a side view. 
         FIG. 8  is a perspective view of an adjustable pedal portion of a pedal simulator made according to the present invention. 
         FIG. 8A  is an exploded view of the adjustable pedal portion of  FIG. 8 . 
         FIG. 9  is a perspective view of an angular adjustable pedal lever portion of the pedal simulator made according to the present invention. 
         FIG. 9A  is an exploded view of the angular adjustable pedal lever portion of  FIG. 9 . 
         FIG. 10  is an exploded perspective view of a crank lever made in a spider construction for direct attachment onto a drive sprocket with an adjustable slide for changing the dimensional length of the crank length. 
         FIGS. 10A and 10B  are opposite perspective views of the crank lever of  FIG. 10 . 
         FIG. 11  is a perspective exploded view of a coupling lever having an adjustable slide portion for changing the dimensional length of the coupling lever. 
         FIGS. 11A and 11B  are opposite assembled views of the adjustable coupling length of  FIG. 11 . 
         FIG. 12  is a top view of the simulator showing a rear wheel and sprockets and chains for chain alignment. 
         FIG. 13  is a perspective of one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present device, as illustrated in  FIGS. 1 through 5 , is directed to a four bar drive link simulator  10  which provides a fast, predictable way to establish optimum dimensions for a four bar drive link mechanism used on bicycles or scooters. 
     To better appreciate the function of the simulator  10 , it is best to refer to an exemplary scooter  100  as shown in  FIGS. 6 ,  6 A and  7  to understand how the four bark drive link mechanism works in an actual vehicle. 
     With reference to  FIGS. 6 ,  6 A and  7 , an improved pedal drive scooter  100  is illustrated. The scooter  100 , as shown, has a frame  110  including a handlebar assembly  120  including the handle bar grips, a shaft  120 A which extends through and is secured to a hub on the frame  110  of the scooter  100 . The shaft extends below the hub to a forked portion which is secured to an axle on the front wheel of the scooter  100 . The steering assembly  120  allows the front wheel to be maneuvered for steering and turning. The frame structure  110  extends from the hub rearwardly to a yoke which connects the rear wheel to the frame  110 . As illustrated, the frame  110  has a step down portion which is connected to the hub and extends substantially downwardly to the bottom of a frame  110  to which a main frame support bar  130  is attached. As shown, at the attachment of the main support bar  130  to the step down portion of the frame  110 , a supporting gusset is welded providing additional strength and stiffness at this location. Welded onto the main support bar  130  is a bottom bracket  160 , this bottom bracket  160  provides a location for a drive mechanism  200  assembly to be mounted. The drive mechanism  200 , as illustrated, includes a drive sprocket  600 . Attached to the drive sprocket  600  is a drive chain which extends rearwardly back to the rear wheel sprocket. The sprocket is attached to the axle of the rear wheel and as the device is operated, turns the rear wheel providing forward propulsion. 
     Attached to each side of the frame  110 , as illustrated in  FIGS. 6 ,  6 A and  7 , are a pair of foot pedals  220 R and  220 L. The foot pedals  220 R and  220 L are attached to the frame  110  at location  50 . This location  50  will be referred to hereafter as the proximal hinge attachment location  50 . The foot pedal  220 L is a mirror image of the foot pedal  220 R. These foot pedals operate in reciprocating motion, up and down and are connected to the drive mechanism  200  to provide forward propulsion. As the pedals are moved in an up and down direction, the sprocket is rotated moving the chain which in turn moves the rear sprocket, and propels the rear wheel. 
     The proximal hinge location  50  extends to the intersection at or near the bend to the reinforced pedal attachment location  24  and extends a distance P, as illustrated. A virtual frame link is created between the proximal hinge location  50  of the frame  110  and the axis if rotation or center of the axle of the drive mechanism  200 . This virtual frame link distance is illustrated in  FIG. 7  as a dimension F. The two ends of the frame link are fixed in location and do not move except rotationally relative to the other. As the pedals  220 L and  220 R reciprocate up and down, the coupling links  320  and the crank links  310 L and  31  OR rotate along with the sprocket  600 . As illustrated, the coupling link  320  extends from the pedal attachment location  24  back to a pin location connecting the coupling links  320  and the crank link  310 L or  310 R. This dimension is identified as C 2 . Extending from the coupling link pin location and crank attachment, a distance of C 1  is illustrated extending back to the drive axle and the sprocket  600 . It is important to note that the coupling link dimension C 2  is substantially larger than the crank link dimension C 1 , as illustrated. Preferably, the coupling link dimension C 2  must be greater than the dimension C 1 , furthermore, it is noted that the proximal hinge location  50  attaching the foot pedal  220 L or  220 R to the frame  110  extends vertically, preferably, above the drive axle location. This vertical distance is indicated as Y in this exemplary scooter design. 
     An important aspect of the dimensional positioning of the four bar linkage is proper rotation of the coupling link  320  and the crank lever  310 L or  310 R. If the locations are not accurately located, the drive mechanism  200  can lock up wherein a lock up phenomena is understood to occur at a top dead center location causing the links to bind, stopping the pedals from moving. A worse problem can occur wherein the linkages can actually reverse rotational direction. In this case a pedal can abruptly slam down as the links rotate opposite to their normal or desired movement. The present invention avoids these issues entirely by a proper selection of four bar link dimensions F, P, C 1  and C 2 . These problems, while understood to exist, were not fully appreciated. Computer software which models and predicts dimensions for four bar linkage systems relies on the axle in the bottom bracket to be the driving location and as such the predicted optimal locations for such a device acted perfectly when one rotated at the axle by hand, but when the drive propulsion was moved to the location  24 , as in the actual scooter device, these software optimum solutions would not operate properly. It was determined that each of the link dimensions and the relationship of C 2  being greater than C 1  and the proximal hinge location were all critical. This meant finding optimal dimensions was not predictable using standard software generated solutions. The performance of the present invention was greatly enhanced by the selection of the link dimensions and attachment locations on the frame  110 . The solution found in the exemplary scooter allows for the dimensions to deviate slightly within normal manufacturing tolerance without the lock up or reversal issues that previously existed in the drive mechanism design. 
     The critical problem of using this type of four bar drive link mechanism in scooters and bicycles was finding a quick, reliable way to design and develop new frames, pedals and drive components that had predictable performance, acceptable manufacturing tolerances and avoiding the lock up or reverse rotational issues that simply were not easily predictable using computer modeling. 
     What was needed was a device that not only was reliable, but one in which the design engineers could confidently mimic real world performance of virtually unlimited range of dimensional variation to find optimal performance characteristics. 
     The present invention simulator shown in  FIGS. 1-5  mimics the performance of the vehicle drive mechanism  200  so that prior to expending the tooling cost on a frame and drive assembly, the designers know with high confidence the performance of the drive mechanism. 
     With reference to  FIGS. 1-5 , the four bar drive link simulator  10  of the present invention is illustrated. As shown, the simulator  10  has a frame assembly  11 , a proximal hinge attachment bracket  20 , a bottom bracket simulator  40 , a pair of crank levers  31 L,  31 R, a pair of coupling levers  32  and a pair of pedal simulator levers  22 L,  22 R. The frame assembly  11  has a plurality of guide rails including at least a proximal hinge adjustment rail  22  and a frame simulator rail  13 . The proximal hinge adjustment rail  22 , as shown on the simulator  10 , extends generally vertically upwardly having guide slots  21  as illustrated. Attached to the proximal hinge adjustment rail  22  is a proximal hinge attachment bracket  20 , this attachment bracket  20  is slidable on the guide rail  22  such that it can move up and down vertically as illustrated. This vertical movement enables the proximal hinge location  50  which will be a location on the frame of the vehicle to be properly duplicated or simulated. The proximal hinge attachment bracket  20  can be snugly secured at any position along the vertical guide rail  22  by using a threaded fastener locking the bracket  20  into a fixed position if so desired. Extending longitudinally along the simulator  10  is the frame simulator rail  13 , similarly having a plurality of guide slots  14  onto which a bottom bracket simulator  40  is attached or otherwise connected. As shown, the bottom bracket simulator  40  can be moved along the frame simulator rail  13  such that it moves forward or aft simulating the location of a bottom bracket that would be welded or otherwise attached to a frame of a vehicle. These two movable brackets  20  and  40  of the simulator  10  establish attachment locations for the crank levers, coupling levers and pedals as illustrated. The proximal hinge location  50  has an axle  23  sticking outwardly such that a pedal simulator  22 L or  22 R can be slipped onto the axle of the proximal hinge bracket  20  to fix the location of the pedals  22 L or  22 R relative to the proximal hinge location  50 . This pedal simulator  22 L or  22 R as shown can move vertically up and down relative to the simulator  10 . As shown in  FIG. 1A , one pedal simulator  22 L is removed from the axle  23  of the proximal hinge bracket  20  clearly exposing the axle  23  as well as a pair of crank levers  31 L,  31 R and coupling levers  32  which are attached to the bottom bracket simulator  40 . The crank lever  31 R and the coupling lever  32  are connected to the pedal simulator  22 R as illustrated in  FIG. 1A  such that they provide an attachment location onto the pedals and enable the drive mechanism  200  to then simulate the movement of the drive mechanism  200  by reciprocating motion of the pedal levers  25 . To accomplish this one simply grasps the ends of the pedal levers  25  and moves them up and down repeating that action to simulate the performance of the drive mechanism  200 . 
     The exploded view of the simulator  10  shown in  FIG. 4 , illustrates the various locations of the components as previously described. As shown, at the forward and rear end of the simulator  10  a pair of laterally extending guide rails  72 ,  74  are attached to the frame simulator rail  13  and proximal hinge guide rail  22  on the forward part of the frame assembly  11 . On the rear part of the frame assembly  11 , as illustrated, a second vertical guide rail  82  is shown along with the lateral guide rail  74  to which a pair of rear wheel mounting brackets  90 ,  92  are shown, the rear wheel mounting brackets  90 ,  92  as illustrated, enable a rear wheel or rear wheel sprocket and hub to be attached such that a chain can be attached to either a sprocket attached on an axle  44  of the second bottom bracket  41  as illustrated or alternatively directly to a sprocket attached on the first bottom bracket  40 . The sprockets not being illustrated in  FIG. 4 , however, it being understood that they can be attached directly onto the axles  42 ,  44  of the bottom bracket simulators  40 ,  41 . 
     Referring to  FIG. 4A , post  150 R and  150 L are shown attached to the pedal assembly and received by openings  152 R and  152 L the respective coupling levers  32 . By attaching the post to the pedal assembly, rather than the coupling lever, the tolerances needed for proper operation are lessened. A bearing can be placed in the coupling opening in one embodiment. 
     As shown in  FIG. 12 , a rear wheel hub assembly  99  can then be attached to the attachment brackets  90 ,  92  for a rear wheel such that chain alignment can be predicted and established using the simulator  10 . This is a second feature of the simulator that enables a direct analysis of chain alignment to be predicted and made utilizing the simulator  10  as shown. 
     For better understanding of the adjustment capability of the simulator  10 , it is understood that the bottom bracket simulator  40  attached to the frame simulator rail  13  enables a movement fore and aft along the simulator  10  whereas the proximal hinge bracket  20  enables a vertical movement up and down the proximal hinge guide rail  22  allowing for adjustment of the virtual frame link dimension F. As the virtual frame dimension F is adjusted, correspondingly the pedal link dimension P from the proximal hinge location  50  to the coupling attachment location  24  at the foot pedals  22 L,  22 R are correspondingly moved. 
     In order to accomplish this movement, the pedal simulator  22 L and  22 R as shown has a forward portion  30 L,  30 R which is shown slightly bent that attaches to the proximal hinge axle  23  at the forward hub end  35 . At the rear end  37  as illustrated in  FIG. 8A , has a slot  34  into which a cylindrical sleeve  38  fits. A screw attachment thread hole  39  has a bolt  65  attached. A thumb lock down nut  66  secures a movable bracket  36  that is attached to the sleeve  38  at the holes  36 A,  36 B enables this location to be moved fore and aft. This allows the link dimension P to be adjusted by simple turning of the threaded fastener or bolt  65  which moves the bracket  36  and correspondingly enables the sleeve  82  in the slot  34  to be moved either forward or aft as so desired. The bolt  65  passes through the hole  36 C in the bracket  36  and the bracket is fixed by the thumb nut  66 . 
     With reference to  FIGS. 9 and 9A , a pedal lever assembly  25  is shown, the pedal lever assembly  25  includes a pair of threaded fasteners  27  to which nuts  26  are applied that extend through a hole  28  locating a pair of angular orientation brackets  25 A to be connected to the lever  25 B as shown, the brackets  25 A have holes  28 A at one end that allow the threaded fastener  27  to slip through a hole  29 B in the lever  25 B and be connected by a nut  26  at the other end. At the arcuate end of the bracket  25 A is an arcuate slot  29 A, the fastener can be slipped through the slot  29 A and into a second hole  29 B in the lever arm  25 B and a nut  26  attached to it. Adjustment of the angle can be achieved by simply loosening the second fastener  27  such that an angular movement in the  29 A of the bracket  25 A can occur. 
     This pedal lever assembly  25  of  FIG. 9  is then welded or otherwise attached to the portion  37  of the bracket  30 L, or  30 R shown in  FIG. 8  and as illustrated in  FIG. 4  in the exploded view. As illustrated, this enables the pedal lever simulator  22 L,  22 R to be adjusted not only dimensionally fore and aft to change the link dimension P by tightening or loosening the bolt  65 , but also angularly to change the angle of the pedal lever assembly  25  such that vertical movement up and down can be adjusted. In doing so, it must be noted that as illustrated, the simulator  10  allows the pedal on one side to be at a substantially horizontal position while on the opposite side the pedal is at the maximum angled position. This is how the pedals operate. The bottom of the stroke which is generally set at a horizontal position and the opposite pedal is at its maximum or peak position of the stroke reciprocating movement alternates these positions and is what drives the drive mechanism in a reciprocating fashion so that the pedals can continuously move. If so desired, at the bottom of the stroke, the angle could be extended slightly below horizontal. 
     The simulator  10  shown in  FIGS. 1 and 4  had fixed coupling levers  32  and fixed crank levers  31 L,  31 R such that the dimensions are fixed C 2  and C 1  respectively. In order to make additional adjustments with regard to these features, and to find optimal coupling lever and crank lever dimensions, it was determined that an adjustment feature could also be provided on a crank lever and a coupling lever. To achieve this, adjustment slots are provided in both of these components. This feature is as illustrated in  FIGS. 10 ,  10 A and  10 B for an exemplary spider crank lever  31 AL, the spider crank lever  31 AL is a type of device that attaches or bolts directly onto a drive sprocket of a vehicle at the four spider arms  314 . As shown in  FIG. 10 , this spider crank lever  31 AL can have a slide  311  that fits in the slot  312 . This slide component  311  is slidably moveable within the slot  312 , but can be fixed at any location within the slot  312  by threaded fasteners  400  as illustrated. The fasteners  400  fit in slots  402  and fasten in the holes  315  in the slider  311 . The opposite perspective views shown in  FIGS. 10A and 10B , show the slide  311  moved to a most forward location wherein the dimension C 1  would be at a minimum on this device. To make an adjustment increasing the length, one would simply move the slider  311  aft and the distance between the attachment and the axle  42  on the bottom bracket simulator  40  and the coupling attachment opening  313  shown in the slider  311  would move in such a direction enabling an increase in length of the dimension C 1 . 
     As shown in  FIGS. 11 ,  11 A and  11 B; a coupling lever  32 A is illustrated having a similar slider  311  that can be inserted into a slot  312  in the coupling lever  32 A. This coupling lever  32 A can then have the slider  311  fastened using threaded fasteners  400  as illustrated. In this component, the coupling lever  32 A can be designed so that adjustments can be made in the dimension C 2  between the pedal attachment location  24  and the crank attachment location  313 . This dimension C 2  can be adjusted increasing or decreasing the length if so desired. As shown in  FIGS. 11A and 11B , the coupling lever  32 A has the slider  311  at a minimum location; movement in an opposite direction in the slot  312  would allow the dimension C 2  to be increased substantially. As such, a large number of variations can occur within the adjustable crank levers  31 AL,  31 AR and coupling levers  32 A. As these elements are placed on the simulator, not only can the dimensions P and F be adjusted along the guide rails  22 ,  13 , but also by providing a pedal lever simulator  22 L,  22 R with an adjustment feature, along with crank levers and coupling levers with slidable adjustment features, every dimension used in establishing a four bar link system can be adjusted. These adjustments can be made either singularly or in combination to create virtually any combination of four bar drive link system dimensions desired within the range of the components ability to be adjusted. This provides the designer with almost an infinite range of selectable solutions for the drive mechanism used in such scooters and bicycles. 
     In using the simulator  10  as illustrated, the drive mechanism can be adjusted in a variety of ways. This drive mechanism dimensions, once established at an optimum by repeated movement of the pedal simulator levers as illustrated, enable the designer to get a feel for the actual movement that will be achieved in the finished scooter or bicycle. Instead of using feet to drive the pedal lever arms  25 , it is desirable to use ones hands and to move these levers up and down simulating the motion of the feet, in doing so the operator gets a feel for the ease in movement of the four bar link system and as such can make minor adjustments until the movement is felt to be optimal. Once the movement is optimally set, the engineer can simply take the measurements relative to the axis of rotation of each of the attachment locations such that these dimensions are established. These dimensions; F, P, C 1  and C 2  are clearly established by the simulator. 
     When using the simulator device  10  the procedure for fixed links outlined below can be followed to establish the four bar drive link dimensions. Step 1: Choose approximate angle of bend for pedals. Step 2: Choose approximate distance between bolts in pedal. Note: increasing distance will decrease pedal stroke angle. In turn, decreasing distance will increase pedal stroke angle. Step 3: Adjust height of proximal hinge and linear distance of bottom bracket until pedal is at an angle of zero degrees from horizontal when at bottom of stroke. Step 4: Continue to adjust linear distance of bottom bracket until drive system rotates freely. Fine tuning is necessary to find the best location of bottom bracket and to obtain tolerances for manufacturing. If pedal stroke angle is not as desired, adjust the distance between the bolts in the pedal. Increase the distance to decrease the angle, in turn, decrease the distance to increase the angle. Repeat steps 3-4. Once desired angle is achieved, adjust the pedal bend angle to zero when at bottom of stroke. 
     When using the simulator device  10  the procedure for adjustable links outlined below can be followed to establish the four bar drive link dimensions. Step 1: Choose approximate angle of bend for pedals. Step 2: Choose approximate distance between bolts in pedal. Note: increasing distance will decrease pedal stroke angle. In turn, decreasing distance will increase pedal stroke angle. Step 3: Choose approximate dimensions for links. Note: Linear length of Crank link should be greater than that of the Coupler link. Note 2: Increasing the length of the Crank link increases tolerances, decreasing the length decreases tolerances. The combined length of the longest length and the shortest length must not be greater than the combined length of the remaining two links. Step 4: Adjust height of proximal hinge and linear distance of bottom bracket until pedal is at an angle of zero degrees from horizontal when at bottom of stroke. Step 5: Continue to adjust linear distance of bottom bracket until drive system rotates freely. Fine tuning is necessary to find the best location of bottom bracket and to obtain tolerances for manufacturing. If pedal stroke angle is not as desired, adjust the distance between the bolts in the pedal. Increase the distance to decrease the angle, in turn, decrease the distance to increase the angle. Repeat steps 3-4. Once desired angle is achieved, adjust the pedal bend angle to zero when at bottom of stroke. Once this has been accomplished, the designer can feel confident that the drive mechanism simulation has provided him with a solution that will provide a good, reliable and predictable drive mechanism. 
     Once this is accomplished, the other aspect of this invention is to use the rear portion of the simulator  10  to attach a wheel or hub  99  as illustrated and to attach sprockets  98  onto the either second bottom bracket  41  or simply the first bottom bracket  40  and to provide for chain alignment, as shown in  FIG. 12 . Chain alignment is critical because in a two chain system, the drive sprocket  98 A is on one side extending back to a smaller sprocket  97  on the second bottom bracket  41  which is also connected on the opposite side to a larger sprocket  98 B which is then connected to a rear wheel hub sprocket  98 C to put drive propulsion to the rear wheel. This creates potential for misalignment of the chains  95 ,  96 ; accordingly it is important that the simulator  10  provides for chain alignment variations and the engineer can then take measurements off of the simulator  10  to establish proper dimensions on the frame and locations that the bottom brackets must be welded to the frame in order to achieve proper chain alignment and also to provide proper attachment locations for the rear wheel assembly onto the frame itself. These features are all achieved with the present invention as illustrated and described above, while variations and minor adjustments can be made, it is understood that this simulator will provide a predictable and reliable way of establishing a four bar drive link system for a scooter or bicycle having reciprocating pedals as described herein. 
     Referring to  FIG. 4A , the invention is shown in more detail. In the past, and as shown in U.S. Pat. No. 8,128,111, a post is attached to the coupling arm. The post is received in a pedal opening defined in the pedal lever at the reinforced pedal attachment location  24 . A bearing can be inserted into the pedal opening allowing the post to more easily rotate in the pedal opening. In this configuration, the precision required in the dimensions of F, P, C 1  and C 2  is critical to proper operating. However, an advantage to the tight tolerances with this configuration is that the rider experiences a motion with little “slack” or “sloppiness” as the various components interact. 
     In one embodiment, the tolerance necessary in to provide for a properly functioning four bar drive link system can be lowered by attaching the post to the pedal arm rather than the coupling lever. Referring to  FIG. 4A , pedal simulators  22 R and  22 L can include a right post  150 R and a left post  150 L. The coupling levers  32  include a right post opening  152 R and a left post opening  152 L for receiving the right and left posts respectively. A coupling bearing can be inserted in to the post openings to assist with the rotation of the posts with the post opening. In this configuration, the dimensions of F, P, C 1  and C 2  need not has such a critical relationship so that variations in the alignment of the post and the post opening that occur in manufacturing are less likely to result in an inoperable four bar drive system. Therefore, when the simulator is used determine the proper dimensions for F, P, C 1  and C 2 , the manufactured drive system itself can vary, especially C 2 . Therefore, when the simulator is used to determine the proper C 2 , the drive system itself can have a different dimension C 2 ′. In one embodiment C 2 ′ is within ten percent (10%) of the dimensions of C 2 . 
     Referring to  FIG. 13 , one embodiment of the invention is shown. The frame assembly  11  include the proximal attachment hinge assembly  20  moveably attached to the guide slot  21 . The forward portions  30 R and  30 L of the pedal simulator at rotatably attached at the proximal hinge point  50 . The forward portions include a front portion block  222 R and  222 L. Forward portion adjustment rods  224 Ra,  224 Rb,  224 La and  224 Lb are slidably attached to the front portion block. Rear portion blocks  226 R and  226 L are attached to the forward portion adjustment rods respectively allowing the distant between the front portion block and the rear portion block to be changed by sliding the front portion rods in an out of the front portion blocks thereby changing the dimensions of the front portion. The forward portion adjustment rods can have a locked position so that they do not slide about the front portion block and an unlocked position allowing the rods to slide within the front portion block. 
     The couplings  32  can each include a front coupling block  228 R and  228 L rotatably attached to the rear portion blocks respectively. Coupling rods  230 Ra,  230 Rb,  230 La and  230 Lb are can be slidably connected to the front coupling block. Rear coupling blocks  232 R and  232 L are attached to the coupling rods. The coupling rods can have a locked position wherein they cannot slide about the front coupling block and an unlocked position where they can slide about the front coupling block changing the distance between the distance between the front coupling block and the rear coupling block. 
     The crank arms  31 R and  31 L can each include a front crank block shown as  234 R and  234 L that is rotatable attached to the rear coupling block. Crank rods  236 Ra and  236 Rb can be slidably attached to the front crank blocks. Rear crank blocks  238 R and  238 L can be attached to the crank rods so that when the crank rod slide about the front crank block, the distance between the front crank blocks and the rear crank blocks is changed. The crank rods can have a locked and unlock position where in the unlocked position the crank rods can slide about the front crank clocks. The rear crank block can be rotatably attached to a axle  42 . 
     The rear forward portion block can include opening  240   a  through  240   d  for receiving the pedal lever  25 . In one embodiment, the pedal lever angle relative to the front portion is changed based upon the opening receiving the pedal lever. Each opening is positing at a different location within the forward portion rear block which in turn effects the leverage experienced by the rider and the motion of the drive system. In one embodiment, a post is orthogonally attached to the forward portion rear block and is receiving in to the front coupling block. By using this configuration, the tolerances needed to provide for proper operation are relaxed. Further, the pedal assembly can to determine performance of a straight pedal lever as well as an angled pedal lever. 
     In operation, when the link dimensions within the pedal assembly, are varied, the pressure on the bearing that can be include in each rotational attachment, are calculated to produce acceptable bearing life predictions. The bearing must have nearly concentric inside ad outside movements for substantial performance life and acceptable noise levels. 
     As illustrated, each of the attachment locations where pivotal motion occurs, it may be desirable to provide bushings or bearings to smooth rotation, assuming the vehicle being simulated employs these components. Therefore, the use of such bushings and bearings is used if they are also used on the vehicle. Furthermore, the axles  42 ,  44  of the bottom brackets can be square or round splined ends, but similarly should match the vehicle being simulated. 
     Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.