TURTURIELLO, George, A. (770 Ridge Street, Honesdale, PA, 18431, US)
| What is Claimed: 1. A front- wheel drive wheelchair comprising: a support frame; a seat mounted to the support frame; wherein each side of the wheelchair comprises: a drive wheel rotatably coupled to the support frame; a drive assembly operatively coupled to the drive wheel and pivotably coupled to the support frame at a motor assembly pivot; a rear suspension arm coupled to the support frame at a suspension arm pivot and extending rearwardly from the suspension arm pivot; and a rear wheel rotatably coupled to the suspension arm, the suspension arm operatively coupled to the drive assembly such that (i) motor torque biases the rear wheels down as the drive wheels encounter an obstacle when the wheelchair is propelled forward, and (ii) motor torque biases the rear wheels up as the rear wheels encounter an obstacle when the wheelchair is propelled backward. 2. The wheelchair of claim 1 , further comprising a first spring coupled between the drive assembly and the suspension arm pivot. 3. The wheelchair of claim 2, wherein the operative coupling of the suspension arm and drive assembly includes a second spring coupled between the suspension arm and the drive assembly. 4. The wheelchair of claim 3, wherein the drive assembly extends generally rearwardly from the motor assembly pivot, and includes a motor, a gearbox, a drive assembly mount affixed to the drive assembly and pivotable on the motor assembly pivot, and an elongate bracket that is rigidly coupled to the drive assembly mount and extends rearwardly therefrom. 5. The wheelchair of claim 1 , wherein the seat is coupled to a tilt mechanism thereby allowing the seat to tilt backwards. 6. The wheelchair of claim 5, wherein (i) the wheelchair has a first center of gravity when the tilt mechanism is not activated, (ii) the wheelchair has a second center of gravity when the tilt mechanism is fully activated, and (iii) the second center of gravity is lower than the first center of gravity. 7. The wheelchair of claim 5, wherein a back portion of the seat is positioned at a point equal to or below the height of the motor assembly pivot. 8. The wheelchair of claim 1 , further comprising a pair of batteries, wherein the batteries are positioned longitudinally on the support frame. 9. The wheelchair of claim 1 , wherein the rear wheel is coupled to the suspension arm with a single taper bearing. 10. The wheelchair of claim 1 , wherein the motor assembly pivot is located proximate to a front end of the support frame. 11. The wheelchair of claim 1 , wherein the suspension arm pivot is located below the motor assembly pivot proximate to a rear end of the support frame. 12. A method of ascending an obstacle in a front- wheel drive powered wheelchair, the method comprising the steps of: (a) providing a front- wheel drive powered wheelchair comprising: a support frame; wherein each side of the wheelchair comprises: a drive wheel rotatably coupled to the support frame; a drive assembly operatively coupled to the drive wheel and pivotably coupled to the support frame at a motor assembly pivot; a suspension arm coupled to the support frame at a suspension arm pivot and extending rearwardly from the suspension arm pivot; and a rear wheel rotatably coupled to the rearward extending arm; (b) positioning the wheelchair such that the front of the drive wheels are in contact with or in close proximity to an obstacle; and (c) urging the rear wheels downward as the drive wheels ascend the obstacle. 13. The method of claim 12, wherein the obstacle is a curb. 14. The method of claim 12, wherein step (c) includes applying a moment to the suspension arm. 15. The method of claim 12, further comprising: (d) positioning the wheelchair such that the back of the rear wheels are in contact with or in close proximity to an obstacle; and (e) urging the rear wheels upward as the rear wheels ascend the obstacle. 16. The method of claim 12, wherein the drive assembly pivots counterclockwise about the motor assembly pivot as the drive wheels ascend the obstacle. 17. The method of claim 12, wherein the suspension arm pivots counterclockwise about the suspension arm pivot as the drive wheels ascend the obstacle. 18. The method of claim 12, wherein the wheelchair further comprises (i) a tilt mechanism coupled to the support frame, and (ii) a seat coupled to the tilt mechanism. 19. The method of claim 18, further comprising the step of: (d) tilting the seat backwards such that the center of gravity of the wheelchair moves down from the wheelchair's original center of gravity. 20. A front-wheel drive powered wheelchair comprising: a support frame; a tilt mechanism mounted on the support frame; a seat mounted to the tilt mechanism; and a pair of opposing drive wheels rotatably coupled to the support frame; wherein (i) the wheelchair has a first center of gravity when the tilt mechanism is not activated and a second center of gravity when the tilt mechanism is fully activated, and (ii) the second center of gravity is lower than the first center of gravity. 21. The wheelchair of claim 20, wherein each side of the wheelchair comprises : a drive assembly operatively coupled to a drive wheel, and pivotably coupled to the support frame at a motor assembly pivot; a suspension arm pivotably coupled to the support frame at a suspension arm pivot and extending rearward from the suspension arm pivot; and a rear wheel rotatably coupled to the suspension arm; wherein (i) motor torque biases the rear wheels down as the drive wheels encounter an obstacle, and (ii) motor torque biases the rear wheels up as the rear wheels encounter an obstacle. 22. The wheelchair of claim 21, wherein a back portion of the seat is positioned at a point equal to or below the height of the motor assembly pivot. 23. The wheelchair of claim 21 , further comprising a first spring coupled between the drive assembly and the suspension arm pivot. 24. The wheelchair of claim 21 , wherein the suspension arm is operatively coupled to the drive assembly by a second spring coupled between the suspension arm and the drive assembly. 25. The wheelchair of claim 21 , further comprising a pair of batteries, wherein the batteries are positioned longitudinally on the support frame. 26. The wheelchair of claim 21 , wherein the rear wheel is coupled to the suspension arm with a single taper bearing. 27. A powered wheelchair comprising: a support frame; a seat mounted to the support frame; wherein each side of the wheelchair comprises: a drive wheel rotatably coupled proximate to an end of the support frame; a drive assembly operatively coupled to the drive wheel and pivotably coupled to the support frame at a motor assembly pivot; a suspension arm coupled to the support frame at a suspension arm pivot and extending from the suspension arm pivot; and a support wheel rotatably coupled to the suspension arm, the suspension arm operatively coupled to the drive assembly such that (i) motor torque biases the support wheels down as the drive wheels encounter an obstacle when the wheelchair is propelled in a first direction, and (ii) motor torque biases the support wheels up as the support wheels encounter an obstacle when the wheelchair is propelled in a second direction, opposite to the first direction. 28. The powered wheelchair of claim 27, wherein the drive wheels are coupled proximate to a front end of the support frame, thereby making the wheelchair a front wheel drive wheelchair. 29. The powered wheelchair of claim 27, wherein the drive wheels are coupled proximate to a back end of the support frame, thereby making the wheelchair a rear wheel drive wheelchair. 30. The powered wheelchair of claim 27, wherein the seat can be oriented such that a user can face either the first direction or the second direction. |
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to United States Provisional Application No. 61/108,695 filed October 27, 2008, the content of which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present technology relates to powered wheelchairs, and more specifically to wheelchair configurations that are capable of assisting in curb-climbing.
BACKGROUND
[0003] Wheelchairs are an important means of transportation for a significant portion of society. Whether manual or powered, wheelchairs provide an important degree of independence for those they assist. However, this degree of independence can be limited if the wheelchair is required to traverse obstacles such as, for example curbs that are commonly present at sidewalks, driveways, and other paved surface interfaces. Accordingly, power wheelchairs have been the subject of increasing development efforts to provide handicapped and disabled persons with independent mobility to assist them in leading even more normal and active lives.
[0004] Powered wheelchairs typically have 4 or 6 wheels and may be configured to assist in curb climbing. For example, some mid-wheel drive wheelchairs, such as those employing an Active-Track™ suspension, available on some powered wheelchairs from Pride Mobility Products Corporation, have pivoting front caster arms that raise or are upwardly biased by motor torque to enhance the capability of the wheelchair to climb curbs. United States Patent Number 6,129,165, which is assigned to the owner of the present invention, discloses biasing of the front wheels by motor torque for curb climbing in mid- wheel drive wheelchairs.
[0005] Front and/or rear wheel drive powered wheelchairs, although not as commercially popular as mid-wheel drive chairs, also are commercially available. There are certain drawbacks, however, to the current curb climbing technology when it is applied to front and/or wheel drive powered wheelchairs. Accordingly, an improved system for assisting front and/or rear wheel drive powered wheelchairs in curb climbing capabilities is needed. [0006] Furthermore, suppliers of wheelchairs are constantly searching for a means to cut costs. Accordingly, a curb climbing system that is capable of being implemented in a front wheel drive wheelchair and/or a rear wheel drive wheelchair is needed.
SUMMARY
[0007] Wheelchair configurations and corresponding methods of use are provided that have a combination of stability, curb climbing, and/or seat tilting capabilities.
[0008] In one embodiment, a wheelchair according to the present invention may include a support frame, and a seat mounted to the support frame either directly or indirectly. Each side of includes a drive wheel, a drive assembly, a suspension arm and a support wheel. The drive wheel may be rotatably coupled proximate to an end of the support frame. The drive assembly may be coupled to the drive wheel and pivotably coupled to the support frame at a motor assembly pivot. The suspension arm may be coupled to the support frame at a suspension arm pivot and may extend from the suspension arm pivot. The support wheel may be rotatably coupled to the suspension arm. The suspension arm may be operatively coupled to the drive assembly such that motor torque may bias the support wheels down as the drive wheels encounter an obstacle when the wheelchair is propelled in a first direction, and motor torque may bias the support wheels up as the support wheels encounter an obstacle when the wheelchair is propelled in a second direction, opposite to the first direction.
[0009] In another embodiment, a wheelchair according to the present invention may include a front- wheel drive wheelchair having a support frame, and a seat mounted to the support frame either directly or indirectly. Each side of the wheelchair includes a drive wheel, a drive assembly, a rear suspension arm, and a rear wheel. The drive wheel may be rotatably coupled to the support frame. The drive assembly may operatively be coupled to the drive wheel and may be pivotably coupled to the support frame at a motor assembly pivot. The rear suspension arm may be coupled to the support frame at a suspension arm pivot and may extend rearwardly from the suspension arm pivot. The rear wheel may be rotatably coupled to the suspension arm. The suspension arm may be operatively coupled to the motor assembly such that motor torque may bias the rear wheels down as the drive wheels encounter an obstacle when the wheelchair is propelled forward, and the motor torque may bias the rear wheels up as the rear wheels encounter an obstacle when the wheelchair is propelled backward.
[0010] The present invention also encompasses a method of ascending an obstacle in a front-wheel drive powered wheelchair. In one embodiment of the method, a front- wheel drive wheelchair is provided. The front-wheel drive wheelchair may include a support frame and each side of the wheelchair may include a drive wheel, a drive assembly, a suspension arm and a rear wheel. The drive assembly may operatively be coupled to the drive wheel and pivotably coupled to the support frame at a motor assembly pivot. The suspension arm may be coupled to the support frame at a suspension arm pivot and may extend rearwardly from the suspension arm pivot. The rear wheel may be coupled to the rearward extending arm. The front wheel drive wheelchair may be positioned such that the front of the drive wheels are in contact with or in close proximity to an obstacle. Once the wheelchair is in position, the rear wheels may be urged downward as the drive wheels ascend the obstacle.
[0011] In another embodiment a front- wheel drive powered wheelchair may include a support frame, a tilt mechanism, a seat, and a pair of opposing drive wheels. The tilt mechanism may be mounted on the support frame and the seat may be mounted to the tilt mechanism. The drive wheels may be rotatably coupled to the support frame. The wheelchair has a first center of gravity when the tilt mechanism is not activated and a second center of gravity when the tilt mechanism is fully activated. Preferably the second center of gravity is lower than the first center of gravity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an isometric view depicting an example embodiment of a front- wheel drive powered wheelchair.
[0013] FIG. 2 is an expanded side view depicting a curb climbing mechanism of the wheelchair shown in FIG. 1.
[0014] FIG. 3A is a side view depicting the wheelchair shown in FIG. 1 as it propels forward over an obstacle
[0015] FIG. 3B is a side view depicting the wheelchair shown in FIG. 1 as it propels backward over an obstacle
[0016] FIG. 4A is a side view depicting the center of gravity of the wheelchair shown in FIG. 1 when the tilt mechanism is not activated. [0017] FIG. 4B is a side view depicting the center of gravity of the wheelchair shown in FIG. 1 when the tilt mechanism is fully activated.
[0018] FIG. 5A is an expanded view depicting a rear wheel coupled to a suspension arm with a taper bearing.
[0019] FIG. 5B is a cut away view of the taper bearing shown in FIG. 5A.
[0020] FIG. 6 is a schematic depicting two batteries positioned longitudinally on a support frame.
[0021] FIG. 7 is an expanded view depicting the curb climbing mechanism shown in FIG. 2 implemented in a rear wheel drive wheelchair.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0022] A preferred structure for a mechanism to facilitate curb climbing is described herein. A preferred structure for a tilt mechanism capable of being used with the curb climbing mechanism is also described herein. An embodiment of a front wheel drive powered wheelchair that employs these technologies is also described. The present invention is not limited to the disclosed configuration of a front wheel drive powered wheelchair, but rather encompasses use of the technology disclosed in any powered wheelchair according to the language of the claims.
[0023] Referring now to the drawings, wherein like reference numerals identify like elements, FIG. 1 depicts a powered wheelchair 10. Powered wheelchair 10 is a front wheel drive powered wheelchair. Here, "front wheel drive" means that the main drive wheels are nominally in the front of the wheelchair. Though not shown in the figures, the term "front wheel drive" as used herein encompasses rigid front anti-tip wheels (that is, wheels supported on an arm that is affixed, without the capability to rotate or pivot, to the frame; either raised or on ground-contacting casters), and front anti-tip wheels supported on an arm that pivots on the frame so long as the arm is not biased by motor torque, such as via a mechanical connection (such as a direct connection or connection through a linkage), even though the front anti-tip wheels may be located nominally in front of the drive wheels. The term "front wheel drive" does not encompass front anti-tip wheels that are biased by motor torque by mechanical linkage between the motor and front anti-tip wheels. The present invention is not limited to front wheel drive wheelchairs unless specifically recited in the claim, and this definition is merely for clarity of description of the preferred embodiment. [0024] Wheelchair 10 is designed to enhance a user's ability to live a more normal life. In that regard, wheelchair 10 is configured to traverse obstacles in both a forward direction and a rearward direction. Therefore, whether wheelchair 10 is going backwards or forwards, it may be capable of overcoming obstacles that traditional wheelchairs might find more difficult.
[0025] As shown in FIG. 1, wheelchair 10 includes a support frame 14, a set of drive wheels 18, a set of drive assemblies 22, a set of rear wheel assemblies 26, and a seat 30.
[0026] Support frame 14 is generally a box-like structure that is formed of welded and/or bolted square and round tubing and formed plates. Support frame 14 is generally rigid, even though the present invention encompasses frames having joints for enhancing the suspension or for any other reason. As shown in FIG. 1, seat 30 is mounted on top of support frame 14. It should be understood, however that seat 30 may either be directly or indirectly mounted to support frame 14.
[0027] As shown in FIG.1 , drive wheels 18 are each rotatably coupled to support frame 14 proximate to the front of support frame 14, and each drive assembly 22 is operatively coupled to one of the drive wheels 18 for propelling wheelchair 10 forwards or backwards. Each drive assembly 22 includes a motor 38 and a gearbox 39. Motors 38 preferably extend longitudinally to the wheelchair 10 (that is, in a direction parallel with straight ahead travel), and gearbox 39 is a right angle gearbox having an output shaft that is transverse to the longitudinal axis.
[0028] As shown in FIG. 1, rear wheel assemblies 26 each include a rear wheel 42 coupled to a suspension arm 46. Each rear wheel 42 preferably is coupled to its respective suspension arm 46 with a single taper bearing 50, thereby allowing rear wheels 42 to swivel about a vertical axis. The low height associated with a single taper bearing is an advantage for when using a tiltable chair in some circumstances. As shown, suspension arms 46 are coupled to support frame 14 and extend rearward to wheelchair 10. Therefore, rear wheels 42 may provide support for wheelchair 10.
[0029] As explained above, wheelchair 10 is capable of traversing obstacles such as curbs. Accordingly, wheelchair 10 has curb climbing capabilities, the mechanism for which is generally referred to as rear arm assemblies 54. While only the arm assembly 54 for the right side of wheelchair 10 will be described, it can be assumed that the arm assembly 54 for the left side of wheelchair 10 is its mirror image. In that regard, FIG. 2 is an enhanced view depicting the arm assembly 54 for the right side of wheelchair 10. As shown, arm assembly 54 incorporates the structure and functions of both the drive assembly 22, and the rear wheel assembly 26. As indicated by arrow F, arm assembly 54 is being implemented in front-wheel drive wheelchair. Accordingly, arrow F shows the forward direction for the front-wheel drive wheelchair.
[0030] As shown in FIG. 2, drive assembly 22 further includes a drive assembly mount 58 pivotable on a motor assembly pivot 60, and an elongate bracket 64 that is rigidly coupled to the drive assembly mount 58 and extends rearwardly therefrom. As shown, motor assembly pivot 60 is coupled to support frame 14 proximate to the front of support frame 14. Accordingly, drive assembly 22 is capable of pivoting about motor assembly pivot 60.
[0031] As shown in FIG. 2, suspension arm 46 is pivotable on a suspension arm pivot 68. As shown, suspension arm pivot 68 is coupled to support frame 14 proximate to the rear of support frame 14 and is lower than motor assembly pivot 60. Suspension arm 46 preferably extends rearward and upward from suspension arm pivot 68.
[0032] Arm assembly 54 also includes a first spring 72 and a second spring 76. Springs 72 and 76 may be any structure capable of absorbing shock. As shown, first spring 72 is coupled between bracket 64 of drive assembly 22 and suspension arm pivot 68, and second spring 76 is coupled between bracket 64 of drive assembly 22 and suspension arm 46. As shown, first spring 72 generally extends downward and at a slight angle from bracket 64, and second spring 76 generally extends downward and at a greater angle from bracket 64.
[0033] FIGs. 3 A and 3B depict wheelchair 10 traversing an obstacle 80 when wheelchair 10 is propelled in the forward direction (FIG. 3A) and in the rearward direction (FIG. 3B). Obstacle 80 may be any obstacle such as curbs that are commonly present at sidewalks, driveways, and other paved surface interfaces.
[0034] As shown in FIG. 3 A, arm assembly 54 can aid wheelchair 10 in traversing obstacle 80 as wheelchair 10 is propelled (that is, moved by motor 38) forward. As shown, when drive wheel 18 is accelerated clockwise and contacts obstacle 80, torque from motor 38 pivots drive assembly 22 counterclockwise about motor assembly pivot 60. As a result, a downward force is translated to suspension arm 46 through second spring 76, and suspension arm 46 is urged to rotate counterclockwise about suspension arm pivot 68. As suspension arm 46, and therefore rear wheel 42, are urged down, weight is taken off of drive wheel 18, and wheelchair 10 can traverse obstacle 80. [0035] As shown in FIG. 3B, arm assembly 54 can aid wheelchair 10 in traversing obstacle 80 as wheelchair 10 is propelled backward. As shown, when drive wheel 18 is accelerated counterclockwise, and when rear wheel 42 contacts obstacle 80, torque from motor 38 pivots drive assembly 22 clockwise about motor assembly pivot 60. As a result, suspension arm 46 is pulled up and rotated clockwise about suspension arm pivot 68. As suspension arm 46, and therefore rear wheel 42 are lifted up, wheelchair 10 is aided in traversing obstacle 80.
[0036] As shown in FIGs. 4A and 4B, wheelchair 10 may also include a tilt mechanism 90 that enables seat 30 to tilt backwards. As shown, tilt mechanism 90 mat be coupled to support frame 14, and seat 30 may be coupled to tilt mechanism 90. Tilt mechanism may include a support member 94 that is capable of pivoting about the support frame 14. Preferably, support member pivots about a point 98 that is located about 1/3 the distance from the back of the support frame 14. As shown in FIG. 4A, wheelchair 10 has a first center of gravity CG that is located at a first height from a support surface. As shown in FIG. 4B, seat 30 may be tilted backwards, that is, support member 94 may pivot about point 98 to thereby move seat 30 through an arc into a fully activated position. When tilt mechanism 90 is fully activated, wheelchair 10 has a second center of gravity CG that is further back and lower than the original first center of gravity. Accordingly, the second center of gravity CG is located a second height from the support surface which is lower than the first center of gravity CG shown in FIG. 4A.
[0037] Preferably, arm assembly 54 is designed to allow tilt mechanism 90 to lower wheelchair 10's center of gravity as much as possible. As shown, when tilt mechanism 90 is fully activated, a back portion of seat 30 is capable of extending into a recess 100 defined by suspension arm 46 and second spring 76. Thus, a back portion of seat 30 may be at a height that is either equal to or below the height of motor assembly pivot 60. Because the center of gravity CG of wheelchair 10 is lower than traditional wheelchairs, standard vehicles may be used to transport wheelchair 10 and its user.
[0038] As shown in FIGs. 5A and 5B, rear wheel 42 is coupled to suspension arm 46 with taper bearing 50. By using taper bearing 50, the overall height of rear wheel assembly 26 may be reduced. As shown in FIG. 5B, taper bearing 50 includes an outer ring 104 and an inner ring 108. As shown, inner ring 108 includes a plurality of rollers 112 and is mounted in outer ring 104.
[0039] As shown in FIG. 6, wheelchair 10 includes batteries 116 supported on frame 14. As shown, batteries 116 are oriented longitudinally to the support frame 14. By orienting the batteries longitudinally, larger drive wheels 18, and larger motors 38 may be used.
[0040] As shown in FIG. 7, features of the invention may be utilized in a wheelchair that is configured to be a rear wheel drive powered wheelchair. Accordingly, arm assembly 54 and support frame 14 may be flipped around so that wheelchair 10 may be a rear wheel drive powered wheelchair. Here, "rear wheel drive" means that the main drive wheels are nominally in the rear of the wheelchair. Though not shown in the figures, the term "rear wheel drive" as used herein encompasses rigid rear anti-tip wheels (that is, wheels supported on an arm that is affixed, without the capability to rotate or pivot, to the frame; either raised or on ground-contacting casters), and rear anti-tip wheels supported on an arm that pivots on the frame so long as the arm is not biased by motor torque, such as via a mechanical connection (such as a direct connection or connection through a linkage), even though the front anti-tip wheels may be located nominally in back of the drive wheels.
[0041] As shown in FIG. 7, a rear wheel drive powered wheelchair includes a support frame 114, a set of drive wheels 118, a set of drive assemblies 122 (each of which includes a motor 138 and a gearbox 139), and a set of front wheel assemblies 126 (each of which includes a front wheel 142 and a suspension arm 146). As shown, support frame 114, drive wheels 118, drive assemblies 122 and front wheel assemblies 126, are identical to support frame 14, drive wheels 18, drive assemblies 22 and rear wheel assemblies 26 of wheelchair 10, except they are reversed. Accordingly wheelchairs that employ these structures may be front wheel drive wheelchairs or rear wheel drive wheelchairs, which allows a user to customize their wheelchair and still benefit from the invention.
[0042] As shown in FIG. 7, an arm assembly 154 which is substantially similar to arm assembly 54, incorporates the structure and functions of both the drive assemblies 122, and the front wheel assemblies 126. As indicated by arrow F, arm assembly 154 is being implemented in a rear-wheel drive wheelchair. Accordingly, arrow F shows the forward direction for the rear- wheel drive wheelchair.
[0043] As shown in FIG. 7, drive assembly 122 includes a motor a drive assembly mount 158 pivotable on a motor assembly pivot 160, and an elongate bracket 164 that is rigidly coupled to the drive assembly mount 158 and extends forward therefrom. As shown, motor assembly pivot 160 is coupled to support frame 114 proximate to the back of support frame 114. Accordingly, drive assembly 122 is capable of pivoting about motor assembly pivot 160. [0044] As shown in FIG. 7, suspension arm 146 is pivotable on a suspension arm pivot 168. As shown, suspension arm pivot 168 is coupled to support frame 14 proximate to the front of support frame 114 and is lower than motor assembly pivot 160. Suspension arm 146 preferably extends forward and upward from suspension arm pivot 168.
[0045] Arm assembly 154 also includes a first spring 172 and a second spring 176. Springs 172 and 176 may be any structure capable of absorbing shock. As shown, first spring 172 is coupled between bracket 164 of drive assembly 122 and suspension arm pivot 168, and second spring 176 is coupled between bracket 164 of drive assembly 122 and suspension arm 146. As shown, first spring 172 generally extends downward and at a slight angle from bracket 164, and second spring 176 generally extends downward and at a greater angle from bracket 164.
[0046] In operation, when the wheelchair is propelled (or otherwise moved) forwards, drive wheels 118 are accelerated clockwise, and when front wheels 142 contact an obstacle, motor assembly 122 will rotate counterclockwise to thereby lift the front wheel assembly 126 to allow the wheelchair to traverse the obstacle. When the wheelchair is propelled (or otherwise moved) backwards, drive wheels 118 are accelerated counterclockwise, and when drive wheels 118 contact an obstacle, motor assembly 122 will rotate clockwise, to thereby urge front wheel assembly 126 down to allow the wheelchair to traverse the obstacle.
[0047] The description of wheelchair 10 and its respective subsystems is for illustration purposes, and the present invention is not intended to the particular descriptions provided herein, nor is the designation of parts into particular subsystems intended to limit the scope of the invention except for the particular structure that is explicitly recited in the claim.