Abstract:
This is a hand-propelled wheeled device for a rider. The device includes: a frame with two sides; a first and second drive wheel rotatably mounted to the two sides; a first hand crank connected to the first drive wheel through a first crank hub, and a first wheel hub that is connected to and rotates the first drive wheel; a second hand crank connected to the second drive wheel through a second crank hub, and a second ratcheting hub that is connected to and rotates the second drive wheel; at least one shifting mechanism to change a leveraging ratio between the first hand crank and the first drive wheel and between the second hand crank and the second drive wheel; a pivoting backrest connected to the frame, wherein the pivoting backrest provides continuous back support to the rider; an adjustable hammock seat connected to the frame; a third support connected to the frame; and a braking mechanism to retard movement of the first and second drive wheels.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to arm powered vehicles, specifically to vehicles propelled by handles mounted on the inside of the right and left drive wheels. The rider uses a circular motion for propulsion.  
         BACKGROUND FOR INVENTION  
         [0002]    Most racing wheelchairs are propelled by pushrims on the outside of the two drive wheels. The rider reaches back and puts the heels of their hands on the pushrims of the two drive wheels. They then push the pushrims down as the wheels rotate.  
           [0003]    There are several weaknesses to this design. First, this design is inefficient, having considerable lost and wasted motion. The power stroke is only approximately one fifth of a revolution requiring one&#39;s hands and arms to return to the starting position after each power stroke. During the return stroke, energy is consumed but not transmitted to the drive wheels as the hands return empty to the original position. Not only is this inefficient, but during this time the wheelchair is out of control and can be particularly dangerous when ascending or descending a ramp or other irregular terrain. Second, this type of motion can also lead to repetitive motion injuries such as carpal tunnel syndrome. Third, the rider&#39;s high position produces a high center of gravity. Fourth, the rider can only inefficiently brake by pushing their hands against the tires or pushrims.  
           [0004]    Advanced racing wheelchairs address these weaknesses by having a small diameter push rim for higher top speed, drive wheels that tilt out at the bottom for stability and an extended front wheel for balance. They are available from such firms as Invacare and Sunrise Medical.  
           [0005]    Many attempts have been tried to change the basic wheelchair design for use by both physically challenged and able-bodied people. They usually fall into five main groups.  
           [0006]    The first group uses levers. This group includes:  
                                           U.S. Pat. No.   Inventor   Title   Date                   4,682,784   Anderson   Wheelchair with Variable   Jul 28, 1987               Ratio Propulsion       4,705,284   Stout   Human Powered Vehicle   Nov 10, 1987                  
 
           [0007]    The second group has pushrims outside the two drive wheels. This group includes:  
                                           U.S. Pat. No.   Inventor   Title   Date                   5,028,064   Johnson   Racing Wheelchair   Jul 3, 1991       3,563,568   Sasse   Variable Rotary Drive   Feb 16, 1971               Mechanism for Wheel Chairs       4,727,965   Zach   Geared Hub with Freewheel for   Mar 1, 1988               Wheel-Chairs                  
 
           [0008]    The third group has small handles outside the two drive wheels. This group includes:  
                                           U.S. Pat. No.   Inventor   Title   Date                   5,037,120   Parisi   Wheelchair Manual Drive   Aug 6, 1991               Mechanism       4,758,013   Agrillo   Hand Crank Wheelchair Drive   Jul 19, 1988                  
 
           [0009]    The fourth group has direct drive handles inside the two drive wheels. This group includes:  
                                           U.S. Pat. No.   Inventor   Title   Date                   4,066,273   Lobar   Toy Car   Jan 3, 1978       4,655,470   Lin   Hand-propelled Wheeled Device   Apr 7, 1987               for Children                  
 
           [0010]    The fifth group has hand cranks in front of the rider using a chain to drive one wheel in front. This group includes:  
                                           U.S. Pat. No.   Inventor   Title   Date                   4,109,927   Harper   Hand Powered and Controlled   Aug 29, 1978               Tricycle                  
 
           [0011]    U.S. Pat. Nos. 4,682,784 and 4,705,284 both use dual reciprocating levers, and have several speeds. The required push/pull arm motion does not fully use the rider&#39;s muscles (only the push moves the vehicle) and the high sitting position (about 13″) is unstable in turns.  
           [0012]    U.S. Pat. No. 5,028,064 has a low, stable sitting position but still uses pushrims. Also, the rider can not easily move back and forth, thus preventing the abdominal and back muscles from helping propel the vehicle.  
           [0013]    U.S. Pat. Nos. 3,563,568 and #4,727,965 have multiple speeds but also have pushrims and a high sitting position.  
           [0014]    U.S. Pat. No. 5,037,120 has an efficient circular arm motion. However, a high sitting position, no brakes, and a rigid seat back hamper the rider&#39;s performance. In addition, the this design has no coasting feature.  
           [0015]    U.S. Pat. No. 4,758,013 has an efficient circular arm motion, brakes and reverse. However, a high sitting position, rigid seat back, and lack of easy frame adjustment also hamper the rider&#39;s performance.  
           [0016]    While U.S. Pat. Nos. 4,066,273 and 4,655,470 use the major muscle groups and have a low, stable seat, they have only one speed, cannot freewheel, and have no brakes. A similar device for children is commercially available through Lakeside Learning.  
           [0017]    U.S. Pat. No. 4,109,927 has a front wheel that is driven by a chain connected to a hand cranked mechanism. The crank and front wheel look like the pedals and back wheel of a bicycle. This concept has an efficient circular arm motion, plurality of speeds and brakes. However, performance is hampered in this model because the rider cannot turn quickly. The front wheel is between the rider&#39;s legs and so its turning angle is limited. Also, sudden stops can cause the rider&#39;s chest to impact the chain sprocket. Similar devices are commercially available through Invacare, Sunrise Medical and Brike.  
           [0018]    In addition, none of these patents show a seat that is comfortable for long periods. The seats are also not ventilated and provide no support for the rider as they rock back and forth. Moreover, most of these patents show a frame that cannot be adjusted for different sized riders.  
           [0019]    It has been shown that the choices in outdoor exercise for physically challenged athletes have limitations. Furthermore, even able-bodied people have limited choices in physical exercise for the upper body. Millions of people run, bicycle, or rollerblade. However, all these exercises are for the lower body. There are few outdoor exercises for the upper body. Two choices are swimming and rowing, but lap pools and lakes are not readily available to most people. The arm-powered Land Rower will give able- bodied, as well as physically challenged, athletes a unique and well designed choice for upper body exercise.  
         SUMMARY OF THE INVENTION  
         [0020]    The present invention is an arm-powered wheeled vehicle for outdoor, upper body exercise. Its main components are a substantially rectangular frame and two drive wheels, which are rotatably mounted along two opposite and parallel sides of the frame. Each side has a rotating handle driving an handle hub attached to a chain that in turn drives a ratcheting hub on the wheel. Different gears or leverages are incorporated in the rotating handle, the handle hub, the ratcheting hub, or any combination of the three. The rider uses a circular motion for propulsion by turning the rotating handle that subsequently drives the wheel. The vehicle has independent right and left brakes for the two drive wheels and a pivoting, adjustable third wheel mounted to the frame in front of the rider. A hammock like seat is attached to the front and rear of the vehicle and passes through a pivoting back support, giving the rider a comfortable, performance-enhancing position. In addition, the pivoting back allows for continuous support while the rider is moving back and forth while rotating the handle. The locations of the back, leg, and foot supports are adjustable. The vehicle can be configured for use by either physically challenged or able-bodied riders.  
           [0021]    It is therefore a broad object of this invention to provide an arm- powered vehicle that can be used by both physically challenged and able- bodied riders.  
           [0022]    It is another object of this invention to provide a vehicle that is propelled by the rider in an efficient way using the large muscles of the upper body in a full range of motion. This object can be accomplished by having the rider use a circular motion for propulsion with power being generated during the entire cycle.  
           [0023]    It is another object of this invention to provide a propulsion method as described above that includes a means to change the gear ratio between the handles and the drive wheels to permit selection of optimum leverages for a particular situation.  
           [0024]    It is another object to have a propulsion system that freewheels or coasts when the rider does not need to propel the vehicle.  
           [0025]    It is another object to have right and left brakes that can be applied independently. The stopping forces should be transmitted to the frame rather than against the rider&#39;s arms.  
           [0026]    It is another object of this invention to provide a performance enhancing seat that is comfortable and lets the rider make efficient use of their upper body power.  
           [0027]    It is another object of this invention to produce a stable vehicle by having a low sitting position.  
           [0028]    It is another object to this invention to have a very maneuverable vehicle. Because it is stable and can pivot on one wheel, the Land Rower can safely have a short turning radius. This object is accomplished by having the rider change direction by using different power to the two drive wheels or by differential braking.  
           [0029]    It is another object of this invention to have the vehicle be adjustable for different sized riders.  
           [0030]    It is another object of this invention to have a vehicle that can be easily disassembled for transport.  
           [0031]    It is another object of this invention to use existing technology so the Land Rower can be manufactured easily.  
           [0032]    Some of the advantages of the present invention include: an efficient propulsion design; a multi-speed transmission; downhill coasting; comfortable, performance enhancing seat; stability and maneuverability; improved brakes; and an adjustable frame.  
           [0033]    These, and other objects and advantages of the present invention, will become more apparent from a consideration of the detailed description of the preferred embodiments, when read in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0035]    [0035]FIG. 1 shows the preferred embodiment from a top view;  
         [0036]    [0036]FIG. 2 shows the preferred embodiment from a side view only showing one wheel and illustrates the motion of the pivoting back support and the motion of the crank handle;  
         [0037]    [0037]FIG. 3 a  shows a view of the crank handle and two optional slide bars;  
         [0038]    [0038]FIG. 3 b  shows the crank handle from a reverse direction of FIG. 3 a;    
         [0039]    [0039]FIG. 4 shows a view of a rider in the preferred embodiment and illustrates the pivoting back support;  
         [0040]    [0040]FIG. 5 shows the preferred embodiment from a side view only showing one wheel and is taken from cutout  2  of FIG. 1;  
         [0041]    [0041]FIG. 6 shows the preferred embodiment from a top view and also illustrates the safety shield between the rider and the wheel spokes;  
         [0042]    [0042]FIG. 7 shows the motions of the crank handle, the handle hub, and the ratcheting hub;  
         [0043]    [0043]FIG. 8 shows an alternate embodiment the crank handle;  
         [0044]    [0044]FIG. 9 shows an alternate embodiment for the brakes;  
         [0045]    FIGS.  10 - 13  show an alternate embodiment for the brakes;  
         [0046]    [0046]FIG. 14 shows an alternate embodiment for the gears; and  
         [0047]    [0047]FIG. 15 shows an alternate embodiment adapted for physically challenged riders. 
     
    
     DETAILED DESCRIPTION  
       [0048]    Chassis  
         [0049]    Referring now to FIG. 1, a preferred embodiment of the Land Rower  50  is illustrated in which a frame  52  is constructed of rectangular aluminum tubing and ¼ aluminum bar stock. Although, aluminum is used, a variety of materials can be substituted, including, but not limited to, steel tubing, graphite material, carbon fiber, etc.  
         [0050]    The frame  52  has two joists  54  running down the middle to support the hammock seat  56 . In this model, the joists  54  are 16″ apart on the inside. The joists  54  are also made from rectangular aluminum tubing. The footrest  58  is mounted between the joists  54  with foot activated brakes  60 , a leg support  62  and a pivoting back support  64 . These three supports are each attached to sliding attachments  66  which slide along the tubing. The location of the supports is adjusted by taking out the locking pins  68  in the tops of the sliding attachments  66 , sliding the attachments  66 , and reinserting the locking pins  68 .  
         [0051]    The chassis is stiffened in this model by a brace  55  which runs across the Land Rower in front of the drive wheels  
         [0052]    In front of the rider is a pivoting front wheel  74 . The front wheel  74  can pivot and be raised or lowered. The wheel assembly consists of a fork component  76  and a wheel  74 . The bottom of the fork component has a plurality of holes  78  on each side so the wheel can be raised or lowered. Raising and lowering the wheel  74  lowers and raises the front of the Land Rower along with the rider&#39;s sitting position. The wheel  74  pivots as the rider turns. The two drive wheels  72  and the pivoting front wheel  74  give the Land Rower three points of contact with the ground and thus making it inherently stable. However, the design of the Land Rower could be easily accommodated to reverse the position of the two drive wheels and the front wheel to put the drive wheels in front and the third wheel behind the rider. In addition, the Land Rower could also be adapted to use a type of ski as the third wheel and chains or tracks for the drive wheels in snow and ice conditions. Moreover, the drive wheels and third wheel could also include shock absorbers or chain tensioners.  
         [0053]    Hammock Seat and Backrest  
         [0054]    Now referring to FIG. 4, the pivoting backrest  64  is very advantageous because it allows the rider to rock back and forth; the action is similar to rowing. The design and pivoting action of the backrest  64  gives the rider continuous, seamless support and minimizes back fatigue. The backrest perimeter frame is made from tubing with cloth  90  stretched horizontally above and below the pivoting support rod  88 . The pivoting support rod  88  is attached to the backrest  64  and goes through two bearings mounted on the sliding devices  66  (shown in FIG. 1) on the right and left joists. The location of the backrest&#39;s top cloth  90  leaves about a ½″ gap above the rod  88 . The hammock  56  runs through this gap and over the pivoting rod  88 . The backrest  64  is able to pivot because the rod  88  can rotate in the bearings inside the sliding devices  66 . The rider&#39;s back gets full support because the hammock passes through the seat.  
         [0055]    Now referring to FIG. 5, the hammock  56  is made of a breathable, washable material and passes through the pivoting backrest  64 . The hammock  56  is attached to a front attachment  80  and to a back attachment  82 . The height of the rider above the ground can be adjusted by adjusting the front and back attachments  80 ,  82 . The preferred embodiment is implemented with the hammock looped around a ½″ tube  84  between the joists in the front and a 1″ tube  86  in the back. The back tube  86  projects about 2″ from the joist on the right side and has a folding crank for turning the tube to adjust the seat height. A hole on the left side is for the locking pin. To adjust the seat height, the rider holds the crank, the locking pin is removed, the crank used to rotate the tube, and the locking pin put back.  
         [0056]    This hand crank feature lets the physically challenged rider slide from their wheelchair across a flat surface and then loosen the hammock for stability. When the ride is over, they can crank the hammock flat again and slide back into their wheelchair.  
         [0057]    Now referring to FIG. 6, optional wheel guard  160  protects the rider from the spokes of the drive wheels. The wheel guard  160  is preferably composed of any durable, lightweight material that will protect the rider and the spokes of wheel.  
         [0058]    Brakes  
         [0059]    The brakes can be used to slow the Land Rower&#39;s speed, as well as, for steering the Land Rower. Now referring to FIG. 1, bicycle caliper brakes  92  are setup to squeeze the rims of the drive wheel  72  in order to slow down the Land Rower. The rider could also steer the Land Rower by independently activating the right and left brakes. The very low center of gravity and resulting stability lets the rider safely turn with surprising speed. The brakes can be activated by a variety of embodiments. One embodiment would have foot activated brakes as part of the footrest is depicted in FIG. 1. In this embodiment, the rider would activate the brakes by pressing down on either the right or the left foot brake  60 . The depressed foot brake  60  would then operate the caliper brakes  92  to retard the movement of the drive wheels  72 . The brake pedals on FIG. 1 can be raised or lowered also.  
         [0060]    Another embodiment uses a Shimano Nexxus hub with coaster brakes as depicted in FIG. 8. In this embodiment, the rider would just start to rotate the crank handles  111  in reverse to stop the drive wheels  72 . In this embodiment, the crank handle  111  is more streamlined than crank handle depicted in FIG. 1 since it does not include the template for gear shifting.  
         [0061]    Another alternative is to have the brakes mounted on handles above the drive wheels as depicted in FIG. 9. In this embodiment, another handle  146  extends just beyond the path of the rider&#39;s hand as it revolves the crank handle. The rider would activate the brakes by squeezing the brake handle  142  with their hands. The brake handle  142  would then active the caliper brakes  92  to retard the movement of the drive wheel  72 .  
         [0062]    Another emodiment for the brakes is depicted in FIGS.  10 - 13 . In this embodiment, the rider rests their feet on the foot rest bar  170  as depicted in FIG. 10. When the rider wants to brake, they push their feet forward to push on the brake pedals  172 . The brake pedals  172  are attached to a brake bar  174 . The brake bar  174  can be raised or lowered on the brake bar support  176  in the relation to the foot rest bar  170  to accommodate different sized people. The foot rest bar  170  is attached to frame  52  by a strap  178  that is attached by bolts  180 . The brake pedal  174  would also be attached to a brake cable  182  that activates the caliper brakes (not shown).  
         [0063]    Now referring to FIG. 11, the rider&#39;s foot  184  rests on the foot rest bar  170  and when needed, pushes on brake pedal  172  mounted on the brake bar  174 .  
         [0064]    [0064]FIG. 12 shows the top view of how the foot rest bar  170 , the brake pedals  172 , the brake bar  174  and the brake bar supports  176  are attached to frame  52 .  
         [0065]    [0065]FIG. 13 shows the back view of how the foot rest bar  170 , the brake pedals  172 , the brake bar  174  and the brake bar supports  176  are attached to frame  52 .  
         [0066]    Drive Mechanism  
         [0067]    The drive mechanism can be implemented in a variety of embodiments. One embodiment utilizes a template method to change gear ratios between the crank handle, and the drive wheel hub. The concept behind the template is for the handle to be farther from the axle of the handle hub when leverage is needed (starting and uphill) and closer to the axle when speed is required (level and downhill).  
         [0068]    Now referring to FIG. 3 a , the handle  96  and its base  98  form a ‘T’; the base  98  slides inside a long flat rectangular tube  112 . A template  100  guides the handle  96  at preset sites  128  in the long tube to give the riders different leverages or speeds. The rider would change leverages by pulling the rod  138  outward, which is spring activated, until it slips out of the holes  128  in the base and the holes  120  in the template  100 , then slide the handle  96  up or down, until it catches the appropriate hole  120  in the template  100  and the appropriate hole  128  in the base. The template  100  and the handle base  98  are held into place by attaching block  115  with four nuts  122  and bolts  118  through base holes  126  and block holes  114 . The template  100  is restricted in movement by attaching pin  116  through pin hole  125  in the template  100  and through pin hole  124  in the base.  
         [0069]    Although, template  100  has five preset holes  120  and is used for advanced riders, another template  110  with three preset holes  120  may be used for beginners. The base  112  as configured, will accommodate both templates  100  and  110 .  
         [0070]    The base  112  is attached to an axle  134  and a chain sprocket  136 . A chain (not shown) transfers the rotational movement from the chain sprocket  136  to ratcheting hub screwed onto the drive wheel (both ratcheting hub and drive wheel not shown in FIG. 3A or  3 B).  
         [0071]    [0071]FIG. 3B shows the back of base  112 , along with the other sides of the axle  134  and the sprocket  136 .  
         [0072]    The preferred embodiment is implemented as the base  112  being composed of a flat square tube approximately 3″ wide and ½″ outside thickness and 20″ long. The base  112  has holes  128  every ¾″ on the side away from the rider. The ‘T’ handle subassembly  98  is implemented with a spring loaded rod and sleeve of aluminum bar stock ⅛″ thick 1½″ wide and 6″ long. The handle  96  is composed of a hollow ½″ inside diameter handle (not shown), that attaches to the 6″ bar stock  98  to make a ‘T’. A slightly larger sleeve (shown as outside of handle  96 ) fits over the ½″ inside diameter tube. The sleeve allows rotation of the rider&#39;s hand as the rider rotates the crank handle. A spring-loaded rod  138  with a loop at one end fits inside the hollow tube. The loop projects outside the handle, toward the rider.  
         [0073]    The template  100  is 1½″ wide, ⅛″ thick and 12″ long with a plurality of holes  120  to vary the leverage of the handle. The clip  116  holds the inserted template  100  in place.  
         [0074]    Referring to FIG. 7 now, the preferred embodiment of the Land Rower uses bicycle components for the drive wheels  72 . The hand crank  112  is attached to a short axle  134 . The base  112  is attached to an axle  134  and a chain sprocket  136 . As stated earlier, the chain  138  transfers the rotational movement from the chain sprocket  136  to the ratcheting sprocket  140  screwed onto the drive wheel  72 .  
         [0075]    This embodiment is similar to a bicycle except the hand crank takes the place of the pedals on a bicycle. The preferred embodiment has an  18  tooth sprocket  136  driving an  18  tooth hub  140 . If the rider wants a higher top speed, they can substitute a  24  tooth sprocket and a longer chain. Low speed, but more torque, can be obtained with a  12  tooth sprocket and a shorter chain.  
         [0076]    Most bicycles have the chain and hub on the right side. This format works for the drive wheel for the Land Rower&#39;s left side, but not the right wheel. However, one solution is to screw the ratcheting hub assembly to the right wheel backwards. A keyway is then used to prevent the hub from unscrewing. Another solution is to reverse the thread on the right-hand wheel and hub to keep the hub from unscrewing.  
         [0077]    Another alternative embodiment utilizes bicycle hubs like those available from Shimano (SG-7R40 and SG-7C21). They have seven speeds and come with and without brakes. The speeds are selected by a cable, which can be built into another handle  142  as shown in FIG. 8.  
         [0078]    Yet another alternative embodiment utilizes wheelchair hubs similar to those used in U.S. Pat. Nos. 3,563,568 and 4,727,965. The designs embodied in those patents discuss ratcheting hubs for wheelchairs but clearly indicate standard wheelchairs with outside pushrims and the usual high sitting position. However, the wheelchair hubs encompassed in those designs could be adapted to have the pushrims, or another type of crank handle similar to that of the preferred embodiment, on the inside of the drive wheel.  
         [0079]    Operation of the Land Rower  
         [0080]    Now referring to FIG. 1 again, the rider sits down on the hammock  56 , grabs the handles  96  and rotates them to the top. They then put their thumbs in the loops  138  of the spring-loaded rods and pull out. This action pulls the other ends of the rods out of the matching holes in the template (shown in detail in FIG. 3A). The rider then slides the handles  96  as far away from the axle  134  as possible and releases the loops  138 . The other end of the spring-loaded rod drops through the matching holes in the template and tube assembly and locks into place (shown in detail in FIG. 3A). The Land Rower is now in first gear. The rider propels the Land Rover forward by rotating the handles forward.  
         [0081]    As speed increases, the rider can change to second gear. With the handles  96  at the top, they put their thumbs in the loops  138 , pull out, and then pull the handles  96  slightly toward the axle. They then release the loops  138  and continue to slide the handles  96  toward the axle  134 . The rod end will be pressed against the template by the spring until it comes to the next hole (shown in detail in FIG. 3A). It will then drop into the hole and lock into place. This process is repeated as the terrain and speed varies. The drop and lock ability makes shifting very easy. In addition, if the hubs allow coasting, there is no reverse gear and the rider goes backwards by rotating the wheels by hand.  
         [0082]    To change the ratios or number of gears, the rider changes templates in the right and left assemblies (shown as template  100  and  110  in FIG. 3A). They pull out the locking pins, pull out the old templates, insert the new templates, and insert the pins to lock them into place. The beginner&#39;s template has three easy gears while an advanced rider&#39;s has five harder ones. The templates can be changed out in about 10 seconds a side.  
         [0083]    If the Land Rower had the Shimano, or similar, multi-speed hubs implemented, the rider would just change gears by clicking the gear selection knob  194  as shown in FIG. 14. Moving the gear selection knob  194  would then change gears on either the wheel hub (not shown) or the handle hub (also not shown). The gear selection knob is attached to another handle  192  that just above the rider&#39;s hand path so that it is easy to change gears as the rider completes a rotation of the crank handle  111 .  
         [0084]    Options for Physically Challenged Riders  
         [0085]    The preferred embodiment for physically challenged riders would omit the footrest brakes and have brake locks  152  as shown in FIG. 15. The brake locks  152  would lock the drive wheels  72  while the rider gets into the Land Rower. In addition, the gears and brakes could be implemented similarly to the handles and brakes of FIG. 8. However, the Shimano Nexxus hub is preferred for the brakes since the rider only need to reverse direction on the crank handle to brake.  
         [0086]    Advantages  
         [0087]    In sum, the Land Rower is intuitive to ride. The action of cranking the handles is like rowing. Its low center of gravity makes it inherently stable at any speed, including at rest. The design, propulsion method and pivoting backrest make it comfortable and fin to ride. The main skill for the rider to master is going around corners. The rider can brake the inside wheel and/or crank the outside wheel. This skill is easier and safer to learn than rollerblading or riding a bike.  
         [0088]    Accordingly, the reader will see that the Land Rower is carefully and simply designed to give physically challenged people an alternative to current racing wheelchairs, as well as provide able-bodied people a unique, upper-body workout. It is a viable complement to running, biking or rollerblading. The Land Rower, as described, has at least seven important features.  
         [0089]    The Land Rower has an efficient propulsion design. The rider uses a circular motion that produces power during the entire movement. The motion uses muscles in the arms, back, shoulders and abdomen, and is a very efficient use of the rider&#39;s efforts.  
         [0090]    In addition, the drive mechanism has a plurality of leverage positions or speeds. In the template transmission version, the handles, set at right angles to the drive wheels, are positioned far from the axle when starting or going uphill. As speed increases and the need for leverage decreases, the rider shifts the handles closer to the axle. The mechanism can be easily modified to change the number of speeds and their leverage relationships. The drawings show a five-speed arrangement for an advanced rider. The geared transmission version uses existing drive hubs such as the Shimano 7-speed.  
         [0091]    Furthermore, the drive mechanism has a coast or freewheel feature. Like a bicycle&#39;s pedals, the handles do not move when the rider is coasting.  
         [0092]    Moreover, the seat incorporates a hammock, and adjustable location s for the pivoting back support, and leg and foot rests. The hammock is attached at the front and back of the chassis. The hammock gives a comfortable, lightweight, shock absorbing, ventilated seat. It passes through the pivoting back support, resting on top of the support&#39;s pivoting axle. The back support pivots with the rider&#39;s movement. The action is similar to rowing. The hammock gives seamless, constant support for the back to minimize back strain and fatigue.  
         [0093]    Additionally, because the handles are on the inside, the rider can sit much lower. Wheelchairs typically have seat heights ranging from 12″ to 15″; the Land Rower rider is about 5″ above the ground. The rider&#39;s height can be adjusted by varying the length of the hammock. The drive mechanism lets the rider pivot the vehicle with one wheel stationary.  
         [0094]    Like most bicycles, the Land Rower uses caliper brakes that squeeze the metal wheel rims. The brake levers can be mounted for either foot or hand activation. Hand controls are for riders with limited or no power in their legs. The right and left brakes can be applied independently for turning corners.  
         [0095]    Lastly, the locations of the back, leg and foot supports can be adjusted for the riders. The third, pivoting wheel can be moved up and down to suit the rider and the racing conditions.  
         [0096]    Although the description above has specific information, it should not be interpreted as limiting the scope of this invention but simply providing illustrations of some of the present aspects of this invention. For example, a snow going version would have wider drive wheels, or belts, and a pivoting ski in the front. The version for wheel-chair athletes can be shortened to accommodate folded legs. The scope of this invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.