# US 8,783,392 B2 · Tracked mobility device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,783,392 B2 - Document ID: US8783392B2 - Status: Granted - Kind: B2 - Application number: 13/765,182 - Filed: 2013-02-12 - Published: 2013-06-20 - Granted: 2014-07-22 - Earliest claimed: 2009-08-04 - Assignees: Freedom One Mobility LLC - Applicants: Travis Underwood - Inventors: Travis Underwood - Web page: https://patentgrep.com/patent/US8783392B2 ## CPC - A61G 5/065: {with three or more wheels mounted on a rotary cross member, e.g. spiders or spoked wheels with small wheels at the end of the spokes} - A61G 5/066: {with endless belts} - A61G 5/125: {for arms} - A61G 5/128: {for feet} - B62D 55/02: with tracks and additional ground wheels {(for multi-purpose tractors B62D49/0635)} - B62D 55/075: Tracked vehicles for ascending or descending stairs, {steep slopes or vertical surfaces}(magnetic or pneumatic ground-engaging parts B62D55/265; chairs or multi-track cycles specially adapted for invalids A61G5/00) - B62D 55/12: Arrangement, location, or adaptation of driving sprockets - A61G 5/042: {Front wheel drive} - A61G 2203/14: Joysticks - A61G: TRANSPORT, PERSONAL CONVEYANCES OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS (appliances for aiding patients or disabled persons to walk A61H3/00); OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES (embalming corpses A01N1/00) - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) ## Abstract A tracked mobility device includes: a) a frame supporting a seat; b) a pair of track drives connected to the frame, with each track drive including a powered center drive wheel, a front roller, a rear roller, and a flexible track, with the center drive wheel having a diameter that is at least 50% greater than the diameter of either the front roller or the rear roller, and c) a rear wheel assembly connected to the frame, with the rear wheel assembly having three wheels sharing a common axle, with the diameter of the center rear wheel being at least 10% larger than the diameter of the two outer rear wheels; d) a source of power to power said center drive wheels; and e) a controller effective for controlling the speed and direction of rotation of each of the track drives. ## Claims ### Claim 1 A tracked mobility device, comprising: a) a frame supporting a seat; b) a pair of track drives connected to said frame, with each track drive comprising a powered center drive wheel, a front roller, a rear roller, and a flexible track; wherein said center drive wheel has a first diameter, said front roller has a second diameter, and said rear roller has a third diameter, wherein said center drive wheel diameter is at least 20% greater than either said front roller diameter or said rear roller diameter; c) a rear wheel assembly connected to said frame and comprising three wheels sharing a common axle, said rear wheel assembly comprising a center wheel having a center wheel diameter, a first outer wheel having a diameter at least 10% smaller than said center wheel diameter, and a second outer wheel having a diameter at least 10% smaller than said center wheel diameter; and d) a controller effective for controlling the speed and direction of rotation of each of the track drives. ### Claim 2 (depends on 1) The tracked mobility device of claim 1 wherein each track drive consists essentially of the powered center drive wheel, the front roller, the rear roller, and the flexible track. ### Claim 3 (depends on 2) The tracked mobility device of claim 2 wherein said center drive wheel diameter is at least 80% greater than either said front roller diameter or said rear roller diameter. ### Claim 4 (depends on 2) The tracked mobility device of claim 2 wherein said center drive wheel has a diameter of between 8 inches and 12 inches, said front roller has a diameter between 4 inches and 8 inches, and said rear roller has a diameter between 4 inches and 8 inches. ### Claim 5 (depends on 4) The tracked mobility device of claim 4 wherein said center drive wheel has a diameter of about 10 inches, said front roller has a diameter of about 5 inches, and said rear roller has a diameter of about 5 inches. ### Claim 6 (depends on 1) The tracked mobility device of claim 1 wherein said inner wheel has a diameter of between 8 inches and 12 inches, said first outer wheel has a diameter of between 6 inches and 10 inches, and said second outer wheel has a diameter of between 6 inches and 10 inches. ### Claim 7 (depends on 1) The tracked mobility device of claim 1 wherein said inner wheel has a diameter of about 10 inches, said first outer wheel has a diameter of about 8 inches, and said second outer wheel has a diameter of about 8 inches. ### Claim 8 (depends on 1) The tracked mobility device of claim 1, wherein said center drive wheel comprises a plurality of outwardly extending ridges defining grooves therebetween, and wherein said track comprises a plurality of inwardly extending ridges defining grooves therebetween, and wherein said outwardly extending ridges and said inwardly extending ridges are sized and spaced such that said inwardly extending ridges fit in the grooves formed by said outwardly extending ridges to allow the center drive wheel ridges to mate with the track ridges as the center drive wheel pulls the track. ### Claim 9 A tracked mobility device, comprising: a) a frame supporting a seat; b) a pair of track drives connected to said frame, with each track drive comprising a powered drive wheel, a first roller, a second roller, and a flexible track; wherein said drive wheel has a first diameter, said first roller has a second diameter, and said second roller has a third diameter, wherein said drive wheel diameter is at least 20% greater than either said first roller diameter or said second roller diameter; c) a rear wheel assembly connected to said frame and comprising three wheels sharing a common axle, with said three wheels comprising a center wheel having a center wheel diameter, a first outer wheel having a diameter at least 10% smaller than said center wheel diameter, and a second outer wheel having a diameter at least 10% smaller than said center wheel diameter; and d) a controller effective for controlling the speed and direction of rotation of each of the track drives. ### Claim 10 (depends on 1) The tracked mobility device of claim 1, wherein a bottom portion of each of said track drives forms a shallow “V” shape that contacts a flat, level ground surface only at an area that is less than the diameter of the center wheel or roller. ### Claim 11 (depends on 9) The tracked mobility device of claim 9 wherein each track drive consists essentially of the powered drive wheel, the front roller, the rear roller, and the flexible track. ### Claim 12 (depends on 11) The tracked mobility device of claim 11 wherein said powered drive wheel has a diameter that is at least 80% greater than either said first roller diameter or said second roller diameter. ### Claim 13 (depends on 11) The tracked mobility device of claim 11 wherein said powered drive wheel has a diameter of between 8 inches and 12 inches, said first roller has a diameter between 4 inches and 8 inches, and said second roller has a diameter between 4 inches and 8 inches. ### Claim 14 (depends on 13) The tracked mobility device of claim 13 wherein said powered drive wheel has a diameter of about 10 inches, said first roller has a diameter of about 5 inches, and said second roller has a diameter of about 5 inches. ### Claim 15 (depends on 9) The tracked mobility device of claim 9 wherein said center wheel has a diameter of between 8 inches and 12 inches, said first outer wheel has a diameter of between 6 inches and 10 inches, and said second outer wheel has a diameter of between 6 inches and 10 inches. ### Claim 16 (depends on 9) The tracked mobility device of claim 9 wherein said center wheel has a diameter of about 10 inches, said first outer wheel has a diameter of about 8 inches, and said second outer wheel has a diameter of about 8 inches. ### Claim 17 (depends on 9) The tracked mobility device of claim 9, wherein said powered drive wheel comprises a plurality of outwardly extending ridges defining grooves therebetween, and wherein said track comprises a plurality of inwardly extending ridges defining grooves therebetween, and wherein said outwardly extending ridges and said inwardly extending ridges are sized and spaced such that said inwardly extending ridges fit in the grooves formed by said outwardly extending ridges to allow the center drive wheel ridges to mate with the track ridges as the drive wheel pulls the track. ### Claim 18 (depends on 9) The tracked mobility device of claim 9, wherein the bottom portion of each of said track drives forms a shallow “V” shape that contacts a flat, level ground surface only at an area that is less than the diameter of the center wheel or roller.