Patent Abstract:
An all-terrain wheelchair includes a rigid and easy-to-assemble frame. The frame has a seating area with armrests toward the rear of the frame and an adjustable footrest area toward the front of the frame. Attached to the rear axle of the frame and outside the seating area are found two large rear wheels of a sufficient width to provide flotation over soft surfaces. Attached to the front axle of the frame in front of the footrest area is a single large wheel of a sufficient width to provide flotation over soft surfaces. An ergonomically designed push handle is found at the upper rear of the frame behind the seating area, which allows an assistant to propel the chair forward or pull it backward. The frame in front of the front wheel forms a pull handle, which allows an assistant to pull the chair forward or push it backward. A locking brake mechanism is attached to the rear axle to prevent a rear wheel from travel and render the wheelchair motionless when necessary.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority of the U.S. Provisional Application 61/895,780 filed on Oct. 25, 2013 entitled “All-Terrain Wheelchair,” the contents of which are hereby incorporated by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     The present invention is in the technical field of wheelchairs. More particularly, the present invention is in the technical field of wheelchairs able to travel over a plurality of surfaces, both “on-road” and “off-road.” 
     For the purposes of this application, wheelchairs can be broken down into two categories: motor-propelled and manually propelled. Motor-propelled wheelchairs feature a motor, electric or other, which provides the energy necessary to move the wheelchair around. Manually propelled wheelchairs rely on the user or another to provide the energy necessary to move the wheelchair. The present invention and the wheelchairs discussed in this application are human propelled. 
     Traditional wheelchairs date back to the 6th century C.E. China and have been refined over thousands of years. In general, traditional wheelchairs feature a seat, backrest, two armrests, two footrests, two large rear wheels and two small front caster wheels. In addition, traditional wheelchairs typically feature handles on the top left and top right corners of the seat so that another may push the wheelchair and user. 
     Traditional wheelchairs feature thin rear wheels of a large diameter, often 50 cm-60 cm in diameter. Two thin caster wheels of a much smaller diameter on the front of traditional wheelchairs allow the user or the person pushing the wheelchair to easily turn it as necessary. Taken together, the wheels and design of a traditional wheelchair provide the most-efficient means of travel possible, as long as the user is on solid ground and a relatively smooth surface. 
     Once a traditional wheelchair is taken off a paved surface, its deficiencies become readily apparent. The caster wheels on the front do not track in a straight line when the user moves a traditional wheelchair forward on sand or other soft surfaces. The thin nature of the front and rear wheels of a traditional wheelchair which make it so well-suited for paved surfaces make it poorly suited for unpaved surfaces. 
     Prior art discloses all terrain and beach wheelchairs encompassing a plurality of designs. The majority of wheelchairs in the prior art utilize designs similar to those of traditional wheelchairs, incorporating fatter, knobby tires similar to those on a mountain bike, or incorporate much wider front and rear wheels to provide floatation on softer surfaces, such as sand. All terrain wheelchairs currently on the market suffer from one or more of the following problems: difficult to push/pull; non-ergonomic pushing handles; difficulty of entry due to high tubing and low seat height; PVC frames which flex excessively and are not well constructed; and the likelihood of ejecting the passenger forward during abrupt stops. 
     The goal of the present invention is to remedy the deficiencies found in traditional wheelchairs and to offer an all terrain wheelchair superior to those on the market. The inventor believes the present invention offers a combination of novel features that, taken in combination, demonstrate a drastic improvement over the prior art. 
     The inventor has performed a search of the prior art and believes the present invention is a new and useful invention for which patent protection is warranted. 
     SUMMARY OF THE INVENTION 
     The present invention is an all-terrain wheelchair incorporating large wheels for ease of travel on non-paved surfaces, an easy-to-enter and comfortable seat, with ergonomic pushing and pulling handles in a frame, which is easily disassembled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the present invention, taken from the front right side; 
         FIG. 2  is a perspective view of the present invention, taken from the back left side; 
         FIG. 3  is a side view of the present invention, showing the right side; 
         FIG. 4  is a top view of the present invention; 
         FIG. 5  is a front view of the present invention; 
         FIG. 6  is a rear view of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The preferred embodiment of the present invention calls for a frame constructed of rigid, strong and lightweight materials, such as aluminum, stainless steel, plastic polymers, carbon fiber tubing, any variation thereof, or any other material suitable for the intended purposes of the present invention. The preferred embodiment of the present invention calls for the seat, backrest and footrest to be constructed of a material of sufficient strength to support the user&#39;s body comfortably. The preferred embodiment of the present invention calls for hollow pressurized wheels constructed of a durable material providing shock absorption, such as polyurethane, polyvinyl chloride or another suitable material. 
     Referring now to the front perspective view of the present invention as shown in  FIG. 1 , there is shown the push handle  100 , rear downtubes  102 , rear axle  104 , longitudinal support bars  106 , front torsional support crossbrace  108 , front axle  110  and front pull assembly  112 . There is also shown the seat  200 , backrest  202 , armrest support tubes  204 , armrest  206  and footrest  208 . There is also shown the rear wheels  300 , front wheel  302  and wheel retention bolts  304 . 
     Referring now to the rear perspective view of the present invention as shown in  FIG. 2 , there is shown the push handle  100 , rear downtubes  102 , rear axle  104 , longitudinal support bars  106 , front torsional support crossbrace  108 , front axle  110  and front pull assembly  112 . There is also shown the seat  200 , backrest  202 , armrest support tubes  204 , armrest  206  and footrest  208 . There is also shown the rear wheels  300 , front wheel  302  and wheel retention bolts  304 . There is also shown the brake foot  400 , brake foot sheath  402 , brake spring  404 , brake catch lever  406  and brake catch channel  408 . 
     Referring now to the side view of the present invention as shown in  FIG. 3 , there is shown the push handle  100 , rear downtubes  102 , rear axle  104 , longitudinal support bars  106 , front torsional support crossbrace  108 , front axle  110  and front pull assembly  112 . There is also shown the seat  200 , backrest  202 , armrest support tubes  204 , armrest  206  and footrest  208 . There is also shown the rear wheels  300 , front wheel  302  and wheel retention bolts  304 . 
     Referring now to the top view of the present invention as shown in  FIG. 4 , there is shown the push handle  100 , longitudinal support bars  106 , front torsional support crossbrace  108 , front axle  110  and front pull assembly  112 . There is also shown the seat  200 , armrest support tubes  204 , armrest  206  and footrest  208 . There is also shown the rear wheels  300  and front wheel  302 . There is also shown the brake foot  400 , brake foot sheath  402 , brake spring  404  and brake catch lever  406 . 
     Referring now to the front view of the present invention as shown in  FIG. 5 , there is shown the push handle  100 , rear downtubes  102 , longitudinal support bars  106 , front axle  110  and front pull assembly  112 . There is also shown the seat  200 , backrest  202 , armrest support tubes  204 , and armrest  206 . There is also shown the rear wheels  300  and front wheel  302 . 
     Referring now to the rear view of the present invention as shown in  FIG. 6 , there is shown the push handle  100 , rear downtubes  102 , rear axle  104  and longitudinal support bars  106 . There is also shown backrest  202 , armrest support tubes  204 , armrest  206  and footrest  208 . There is also shown the rear wheels  300  and front wheel  302 . There is also shown the brake foot  400 , brake foot sheath  402 , brake spring  404 , brake catch lever  406  and brake catch channel  408 . 
     Referring to the construction of the frame  100 - 112  as shown in all FIGS., the frame  100 - 112  is comprised of a plurality of mated tubes. The preferred embodiment utilizes thumbscrews to join the various parts of the frame assembly  100 - 112  so that the user may easily disassemble and reassemble as required. Alternative embodiments of the present invention may utilize nuts and bolts, posts/pins and clips or any other method that would securely the tubing of the frame assembly  100 - 112 . The push handle  100  meets the rear downtubes  102  and continues down to the rear axle  104 . The longitudinal support bars  106  meet in the center of the rear axle  104  and continue forward past the seat  200 , footrest  208 , front torsional support crossbrace  108 , and front axle  110  to the front pull assembly  112 . 
     One goal of the present invention is to allow the user to easily assemble and disassemble the wheelchair. Many users of the present invention will continue to use traditional wheelchairs for travel on paved surfaces, but desire a portable wheelchair when the user wishes to travel on non-paved surfaces, such as the beach. The preferred embodiment calls for the frame assembly  100 - 112  to be constructed of a plurality of tubing, which may be easily joined utilizing thumbscrews, or other suitable attachment mechanism. The preferred embodiment of the present invention calls for separate tubing and attachment points in the following general areas: on the armrest support tubes  204  behind the armrests  206 ; on the longitudinal support bars  106  roughly midway between the front edge of the seat  200  and the rear edge of the footrest  208 ; on the rear downtubes  102  and below the bottom edge of the backrest  202 . Alternative embodiments of the present invention may utilize a different configuration of attachment points. The attachment points of the preferred embodiment of the present invention are placed in such a manner as to allow the user to stack the various portions of the present invention on each other when disassembled, allowing for storage in the most-compact manner possible. 
     To disassemble the frame assembly  100 - 112 , the user removes the attachment mechanisms from the various attachment points and slides the corresponding portions of the frame  100 - 112  away from their mates. To reassemble the frame assembly  100 - 112 , the user reverses the process. 
     Referring in more detail to the seat  200 , backrest  202  and footrest  208  as shown in all Figs., the seat  200 , backrest  202  and footrest  208  are all constructed in such a manner as to be easily removable from, and attached to, the frame assembly  100 - 112  of the wheelchair. The preferred embodiment of the present invention calls for the seat  200 , backrest  202  and footrest  208  to be constructed so that the user may slide them onto the appropriate portions of the frame assembly  100 - 112 . Alternative embodiments of the present invention allow for other attachment mechanisms, such as hook and loop, rivets, or any other mechanism that would securely hold each part in place on the frame assembly  100 - 112 , while allowing quick disassembly and reassembly. 
     Referring in more detail to the rear wheels  300  and their attachment to the frame assembly  100 - 112  as shown in the FIGS., the rear wheels  300  are designed to slide over the terminals of the rear axle  104  and remain securely in place as long as the wheel retention bolts  304  are fastened to the terminals of the rear axle  104 . Removing the wheel retention bolts  304  allows the user to slide the rear wheels  300  off either terminal of the rear axle  104 . To reattach the rear wheels  300 , the user slides the rear wheels  300  onto the terminals of the rear axle  104  and screws the wheel retention bolts  304  in place. Alternative embodiments of the present invention may use different securement mechanisms, such as retention clips, to retain the rear wheels  300  than the wheel retention bolts  304  referenced in the drawings. 
     The preferred embodiment of the present invention features a brake mechanism as shown in  FIGS. 2, 4 and 6 . The brake mechanism features a brake foot  400 , brake foot sheath  402 , brake spring  404  and brake catch lever  406 , which is further enclosed in a brake catch channel  408 . The brake foot  400  is designed to slide horizontally within the brake foot sheath  402 . At the internal end of the brake foot  400 , there is found a brake catch lever  406 , which hooks into a catch in the brake catch channel  408 , when it is desirable to have the brake disengaged and the wheelchair move freely. A brake spring  404  runs between the brake catch lever  406  and its outer attachment point on one of the armrest support tubes  204 . When the user wishes to engage the brake, he slides the brake catch lever  406  upwards and away from the catch in the brake catch channel  408 , at which point, the brake spring  404  pulls the brake catch lever  406 , and consequently the brake foot  400 , outward toward the rear wheel  300 , locking the brake foot  400  against a bolt within the rear wheel  300  or into a channel within the rear wheel  300 . 
     To use the wheelchair, the user is placed onto the seat  200 , where he may rest comfortably with his back on the backrest  202  and his arms on the armrests  206 . If desired, the user may push forward on the rear wheels  300  to propel the wheelchair forward. The larger rear wheels  300  and front wheel  302  found on the present invention allow him to travel over both hard and soft surfaces with ease. 
     The present invention is designed in such a way that another may push or pull the user over hard and soft surfaces with ease. The push handle  100  is ergonomically designed to provide the most optimal transfer of energy from the assistant to the wheelchair so that the assistant may push it for long distances without tiring. Furthermore, the front pull assembly  112  allows an assistant to lift the front of the wheelchair and easily pull the user if so desired. The overall design of the frame  100 - 112  and placement of the seat  200  and backrest  202  in relation to the rear axle  104  and rear wheels  300  keeps the users weight centered over the rear wheels  300  so the assistant may pull the chair without his arms quickly tiring. 
     The present invention is designed to fit users of a variety of heights. The front torsional support crossbrace  108  features clamps on the ends where it attaches to the longitudinal support bars  106 . The front torsional support crossbrace  108  comprises two pieces of tubing, one within the other. To adjust the position of the front torsional support crossbrace  108  on the longitudinal support bars  106 , and consequently the placement of the footrest  208 , the user loosens the clamps on the front torsional support crossbrace  108  and moves it about the longitudinal support bars  106  to the position most comfortable to him. Furthermore, the front torsional support crossbrace  108  may feature padding where it meets the footrest  208  for comfort. 
     While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.

Technology Classification (CPC): 0