Low resistance track assembly and stair climbing wheelchair

Abstract

The utility model relates to a wheelchair technical field provides a low resistance track assembly, including track frame, the track frame includes two opposite setting frame board, the both ends of track frame are equipped with driving pulley and driven pulley respectively, and the both sides around the track of interconnection, driving pulley rotation sleeve connection is in driving axle, and driven pulley rotation sleeve connection is in driven axle, rotation is provided with a plurality of along track transmission direction arrangement's bearing wheel between two frame boards, the rolling of bearing wheel abuts on the inner surface of track located below it, and the diameter of bearing wheel is no more than 15mm. By this, the utility model discloses through setting up close arrangement's bearing wheel, and the load of track bearing is changed into rolling friction from sliding friction, and the drive resistance of track is greatly reduced. Bearing wheel diameter is small, and densely arranged, and the gap is small. When track is pressed on the object such as step, the deformation of track cannot enter the gap, avoids being stuck between two bearing wheels. The utility model provides a kind of climb wheel.

Description

Technical Field

[0001] This utility model belongs to the field of wheelchair technology, and in particular relates to a low-resistance track assembly and a stair-climbing wheelchair. Background Technology

[0002] For example, the stair-climbing wheelchair disclosed in Chinese Patent 2024211970180 uses tracks to move the wheelchair up and down stairs. The tracks are usually mounted on a track frame, with rollers only at the ends and corners, while the rest of the straight sections are supported by support plates.

[0003] When going up and down stairs, the weight of both the wheelchair and the passenger is borne by the tracks. Since the tracks make point contact with the stairs, this creates significant stress concentration, greatly increasing the friction between the tracks and the support plates, thus increasing energy consumption. This necessitates the use of a larger drive motor, increasing manufacturing costs.

[0004] In conclusion, the existing technology obviously has inconveniences and defects in practical use, so it is necessary to improve it. Utility Model Content

[0005] To address the aforementioned shortcomings, this utility model primarily provides a low-resistance track assembly, solving the technical problem of high friction and increased energy consumption during track movement.

[0006] To address the aforementioned problems, this utility model provides a low-resistance track assembly, including a track frame; the track frame includes two opposing frame plates; each end of the track frame is respectively provided with a drive pulley and a driven pulley; the drive pulley is rotatably sleeved on a drive shaft, and the driven pulley is sleeved on a driven shaft; the ends of the drive shaft and the driven shaft are respectively disposed on the frame plates on corresponding sides; a track is wound between the drive pulley and the driven pulley;

[0007] Multiple load-bearing rollers arranged along the conveying direction of the track are rotatably disposed between the two frame plates; the rolling of the load-bearing rollers abuts against the inner surface of the track located below them; the diameter of the load-bearing rollers does not exceed 15mm.

[0008] According to the low-resistance track assembly of this utility model, the difference between the center distance of two adjacent load-bearing wheels and the diameter of the load-bearing wheel does not exceed 1 mm.

[0009] According to the low-resistance track assembly of this utility model, the load-bearing wheel is a bearing, and its inner ring is fixedly sleeved on the load shaft; the two ends of the load shaft are fixed on the frame plate on the corresponding side.

[0010] According to the low-resistance track assembly of this utility model, a plurality of inner protrusions are provided at equal intervals on the inner surface of the track; a notch structure is provided at the center of the inner protrusions, and the notch structures of each inner protrusion together form a limiting wheel groove for accommodating the load-bearing wheel.

[0011] According to the low-resistance track assembly of this utility model, a plurality of outward protrusions are provided at equal intervals on the outer surface of the track.

[0012] According to the low-resistance track assembly of this utility model, the inner and outer protrusions on the inner and outer surfaces of the track are arranged opposite each other.

[0013] According to the low-resistance track assembly of this utility model, the track frame has a bending structure; the concave position of the bending structure is provided with a pressing wheel that presses against the outer surface of the track; the convex position of the bending structure is provided with a redirecting wheel that rolls against the inner surface of the track.

[0014] According to the low-resistance track assembly of this utility model, the driven pulley is connected to a tension adjustment assembly mounted on the outer wall of the frame plate; the tension adjustment assembly includes a support block fixed on the outer wall of the frame plate and an adjustment block slidably mounted on the outer wall of the frame plate; the adjustment block is threaded with an adjustment bolt; the support block has a threaded hole, and the bolt head of the adjustment bolt abuts against the threaded hole.

[0015] The frame plate is provided with adjustment holes, and the driven shaft passes through the adjustment holes and is fixed on the adjustment block.

[0016] A stair-climbing wheelchair, capable of both flat-ground and stair-step walking postures, includes a chair frame with a seat and backrest. Two front wheels are mounted on the front end of the chair frame. A tilting pivot is mounted on the chair frame. A swing arm is fixed to each end of the tilting pivot, and a rear wheel is mounted on each swing arm. A tilting electric cylinder is also mounted on the chair frame to drive the tilting pivot in both forward and reverse directions. Two sets of inclined low-resistance track assemblies are mounted on the rear side of the chair frame. A stair-climbing motor is installed between the track frames of the two low-resistance track assemblies to drive the two tracks to rotate synchronously.

[0017] According to the stair-climbing wheelchair of this utility model, one end of the two track frames tilts downward and extends into the space area formed between the two front wheels;

[0018] The chair frame is equipped with a fulcrum shaft, and both track frames are rotatably connected to the fulcrum shaft; the lower end of each track frame can reciprocate around the fulcrum shaft; specifically:

[0019] When the stair-climbing wheelchair switches from a flat-ground walking posture to a stair-walking posture, the lower end of the track frame swings downward.

[0020] When the stair-climbing wheelchair switches from a stair-walking posture to a flat-ground walking posture, the lower end of the track frame swings upward to return to its original position.

[0021] Two downward pressing cams are fixedly sleeved on the tilting shaft; the track frame is provided with a follower wheel for rolling contact with the downward pressing cam on the corresponding side; a return spring is connected between the track frame and the chair frame; the downward pressing cam has a protrusion;

[0022] The stair-climbing wheelchair switches from a flat-ground walking posture to a stair-step walking posture: the tilting pivot rotates, the protrusion of the downward pressing cam contacts the follower wheel, causing the track frame to swing downward around the pivot axis;

[0023] When the stair-climbing wheelchair switches from a stair-walking posture to a flat-ground walking posture: the tilting pivot rotates in the opposite direction, the return spring contracts and pulls the track frame to swing upward around the fulcrum until it returns to its original position.

[0024] In summary, the low-resistance track assembly of this invention, by incorporating closely arranged load-bearing rollers within the track frame, bears the load of the track. It transforms sliding friction into rolling friction, significantly reducing the driving resistance of the track. The coefficient of friction is reduced by more than 80%, allowing the same motor to drive a larger load. The load-bearing rollers have a small diameter and are densely arranged, with minimal gaps between adjacent rollers. When the track presses against sharp protrusions such as steps, the inward deformation of the track cannot enter these gaps, preventing it from getting stuck between the two load-bearing rollers. This invention also provides a stair-climbing wheelchair. Attached Figure Description

[0025] Figure 1 This is a structural schematic diagram of the low-resistance track assembly of this utility model;

[0026] Figure 2 This is a schematic diagram of the internal structure of the low-resistance track assembly of this utility model;

[0027] Figure 3 yes Figure 1 Schematic diagram of the structure of region A in the middle;

[0028] Figure 4 yes Figure 2 Schematic diagram of the structure of region C in the middle;

[0029] Figure 5 yes Figure 2 A schematic diagram of the planar structure along direction B;

[0030] Figure 6 This is a structural schematic diagram of the stair-climbing wheelchair of this utility model;

[0031] Figure 7 yes Figure 6 The main view;

[0032] Figure 8 yes Figure 6 A schematic diagram of the structure in direction A;

[0033] Figure 9 This is a schematic diagram of the drive structure of the stair-climbing wheelchair of this utility model;

[0034] Figure 10 yes Figure 9 Schematic diagram of the structure in direction B;

[0035] Figure 11 This is a structural schematic diagram of the climbing preparation posture of this utility model;

[0036] Figure 12 This is a structural schematic diagram of the initial stage of climbing stairs according to this utility model;

[0037] Figure 13 This is a schematic diagram of the structure of this utility model for walking along stair steps;

[0038] Figure 14 This is a structural schematic diagram of the reset stage of this utility model;

[0039] In the diagram: 1-Chair frame, 11-Controller, 12-Seat plate, 13-Backrest, 14-Return spring; 2-Front wheel, 3-Rear wheel, 31-Swing arm; 4-Crawler frame, 41-Reinforcing shaft, 42-Pivot shaft, 43-Pressing pulley, 44-Stair climbing motor, 45-Crawler drive shaft, 46-Follower wheel, 47-Redirecting wheel, 48-Frame plate, 481-Adjusting hole; 49-Drive pulley, 491-Driven shaft, 492-Driven pulley; 5-Tilting cylinder, 51-Drive rod, 52-Tilting shaft, 53-Pressing cam; 6-Crawler, 61-Inner protrusion, 62-Outer protrusion, 63-Bearing wheel, 631-Load shaft; 64-Limit wheel groove; 7-Support block, 71-Adjusting block, 72-Adjusting bolt; 100-Flat ground, 200-Step. Detailed Implementation

[0040] See Figure 1 This utility model provides a low-resistance track assembly, including a track frame 4; combined with Figure 2 The track frame 4 includes two opposing frame plates 48; each end of the track frame 4 is provided with a drive pulley 49 and a driven pulley 492; the drive pulley 49 is rotatably sleeved on the drive shaft, and the driven pulley 492 is rotatably sleeved on the driven shaft 491; the ends of the drive shaft and the driven shaft 491 are respectively arranged on the frame plates 48 on the corresponding sides; a track 6 is wound between the drive pulley 49 and the driven pulley 492.

[0041] See Figure 4 A plurality of load-bearing rollers 63 are rotatably arranged between the two frame plates 48 along the conveying direction of the track 6; the rolling of the load-bearing rollers 63 abuts against the inner surface of the track 6 located below them; the diameter of the load-bearing rollers 63 does not exceed 15mm.

[0042] The load-bearing rollers 63 should not come into contact with each other, minimizing the distance between them to achieve a close arrangement. This prevents the track from being squeezed in and improves load-bearing capacity. Furthermore, the minimum gap between two adjacent load-bearing rollers 63 should not exceed 1 mm; that is, the difference between the center distance and the diameter of two adjacent load-bearing rollers 63 should not exceed 1 mm. More preferably, the minimum gap between two adjacent load-bearing rollers 63 can be 0.5 mm.

[0043] Optionally, the load-bearing roller 63 is a bearing, and its inner ring is fixedly sleeved on the load shaft 631; both ends of the load shaft 631 are fixed on the corresponding side of the frame plate 48. The bearing is preferably made of metal, which is small in size and has high load-bearing strength. It does not deform when bearing load, and can further reduce the minimum gap between two adjacent load-bearing rollers 63, such as reducing the gap to within 2mm.

[0044] Combination Figure 5 This invention features closely spaced load-bearing wheels 63 within the track frame 4 to support the load of the track 6. This transforms sliding friction into rolling friction, significantly reducing the driving resistance of the track 6. Experiments conducted by the inventors have shown that the power consumption of driving the track 6 is reduced by more than one-third, allowing the same motor to drive a larger load. The load-bearing wheels 63 have a small diameter and are densely arranged, with minimal gaps between adjacent wheels. When the track 6 presses against a sharp protrusion such as a step 200, the inward deformation of the track 6 makes it less likely to enter the gap, preventing it from getting stuck between the two load-bearing wheels 63. Based on actual usage scenarios and the load design requirements of wheelchairs, this invention also features a thicker track 6, further reducing inward deformation and making it even less likely to get stuck between adjacent load-bearing wheels 63.

[0045] As one embodiment, the inner surface of the track 6 is provided with a plurality of inner protrusions 61 at equal intervals; the center of each inner protrusion 61 is provided with a notch structure, and the notch structures of each inner protrusion 61 together form a limiting wheel groove 64 for accommodating the load-bearing wheel 63.

[0046] While the load-bearing roller 63 is rolling, its two sides are limited by the inner protrusion strip 61, which plays a role in real-time correction of the track 6.

[0047] Optionally, the outer circumference of the driving pulley 49 and the driven pulley 492 is provided with wheel grooves that engage with the inner protrusion 61 to prevent slippage of the track 6 during transmission. Preferably, the driving pulley 49 and the driven pulley 492 of this invention are both synchronous pulleys.

[0048] Furthermore, multiple external protrusions 62 are evenly spaced on the outer surface of the track 6; a groove is formed between two adjacent external protrusions 62 to increase the grip of the step 200 when walking. Even better, the inner protrusions 61 and the outer protrusions 62 on the inner and outer surfaces of the track 6 are arranged opposite each other; this improves the strength and load-bearing capacity of the track 6.

[0049] As one implementation, the track frame 4 has a bending structure, and a pressure roller 43 for pressing the track 6 is provided in the concave position of the bending structure; this allows the track to smoothly complete the bending transition. At the same time, the pressure roller 43 tensions the track.

[0050] The outwardly protruding part of the bent structure is provided with a reversing wheel 47; the track rolls in cooperation with the reversing wheel 47, realizing rolling reversal at the bent part and reducing the power consumption of driving track 6.

[0051] See Figure 3 In one embodiment, the driven pulley 492 of this utility model is connected to a tension adjustment assembly mounted on the outer wall of the frame plate 48; the tension adjustment assembly includes a support block 7 fixed on the outer wall of the frame plate 48 and an adjustment block 71 slidably mounted on the outer wall of the frame plate 48; the adjustment block 71 is threadedly fitted with an adjustment bolt 72; the support block 7 has a threaded hole, and the bolt head of the adjustment bolt 72 abuts against the threaded hole;

[0052] The frame plate 48 is provided with an adjustment hole 481, and the driven shaft 491 passes through the adjustment hole 481 and is fixed on the adjustment block 71; turning the adjustment bolt 72 can make the adjustment block 71 slide along the outer wall of the frame plate 48, thereby adjusting the tension of the track 6.

[0053] See Figures 6-10 This utility model also provides a stair-climbing wheelchair, including a chair frame 1, on which a seat 12 and a backrest 13 are provided; two front wheels 2 are installed at the front end of the chair frame 1; a tilting shaft 52 is provided on the chair frame 1; a swing arm 31 is fixedly connected to each end of the tilting shaft 52, and a rear wheel 3 is installed on the swing arm 31; a tilting electric cylinder 5 for driving the tilting shaft 52 to rotate in the forward and reverse directions is also installed on the chair frame 1.

[0054] Two sets of the aforementioned low-resistance track assemblies are installed on the side and rear of the chair frame 1; a stair-climbing motor 44 for driving the two tracks 6 to rotate synchronously is also installed between the track frames 4 of the two low-resistance track assemblies.

[0055] Optionally, as one embodiment, the stair-climbing motor 44 is driven by a track drive shaft 45, and the two ends of the track drive shaft 45 are respectively driven by a drive pulley 49 on the corresponding side.

[0056] Furthermore, a reinforcing shaft 41 is connected between the two track frames 4 to enhance the overall rigidity and load-bearing capacity of the two track frames 4.

[0057] As one embodiment, the downward-sloping ends of the two track frames 4 extend into the space area formed between the two front wheels 2;

[0058] Combination Figure 7 Because there is no distance between the lower end of the track frame 4 and the front wheel 2 in the direction of travel, when the front wheel 2 hits an obstacle, it lifts up, and the lower end of the track frame 4 lifts up accordingly; after passing through, the front wheel 2 lowers to contact the ground, and the lower end of the track frame 4 lowers down accordingly, thus avoiding the phenomenon of being stuck by the obstacle.

[0059] This utility model of a stair-climbing wheelchair has both flat ground walking posture and stair walking posture;

[0060] Combination Figure 11 In the flat ground walking posture, both the front wheel 2 and the rear wheel 3 are in contact with the flat ground 100, jointly supporting the stair-climbing wheelchair to walk on the flat ground 100; in this walking posture, the track 6 is out of contact with the flat ground 100.

[0061] See Figure 13 In the stair-walking posture, track 6 contacts the stair steps, driving the stair-climbing wheelchair to walk along the stair steps; in this walking posture, both front wheel 2 and rear wheel 3 are out of contact with the stair steps.

[0062] Combination Figure 9 The tilting pivot 52 rotates, which can drive the two swing arms 31 to swing, thereby completing the posture switching of the stair-climbing wheelchair to tilt backward or return to its original position.

[0063] See Figure 8 In one embodiment, the chair frame 1 is provided with a fulcrum shaft 42, and both track frames 4 are rotatably connected to the fulcrum shaft 42; the lower end of the track frame 4 can reciprocate around the fulcrum shaft 42; specifically:

[0064] Combination Figure 11 and Figure 12 When the stair-climbing wheelchair switches from a flat-ground walking posture to a step-walking posture, the lower end of the track frame 4 swings downward, reducing the distance between the track 6 and the flat ground 100. Then, when the stair-climbing wheelchair tilts, the track can smoothly contact the flat ground 100.

[0065] Combined Figure 14 When the stair-climbing wheelchair switches from a stair-walking posture to a flat-ground walking posture, the lower end of the track frame 4 swings upward to reset.

[0066] In this embodiment, the track frame 4 can rotate around the pivot axis 42. When walking on flat ground, the lower end of the track frame 4 is retracted, which has a large distance relative to the ground, enabling it to better avoid protruding structures or objects on the road surface and improve the wheelchair's adaptability to road conditions.

[0067] Furthermore, when the stair-climbing wheelchair is in a flat-ground walking posture, the distance between the lower end of the track frame 4 and the lowest point of the front wheel 2 is not less than 3.5cm, preferably 5-10cm. Those skilled in the art can make adaptive settings according to the specifications of the front wheel 2 or the usage scenario of the wheelchair. This ensures that when the track frame 4 is retracted, its lower end is higher than the ground, making it less susceptible to collisions with protruding structures or objects.

[0068] In one embodiment, two downward pressing cams 53 are fixedly sleeved on the tilting shaft 52; the track frame 4 is provided with a follower wheel 46 for rolling contact with the downward pressing cam 53 on the corresponding side; a return spring 14 is connected between the track frame 4 and the chair frame 1; the downward pressing cam 53 has a protrusion.

[0069] When the stair-climbing wheelchair switches from a flat-ground walking posture to a stair-walking posture: the tilting shaft 52 rotates, the protrusion of the downward pressing cam 53 contacts the follower wheel 46, causing the track frame 4 to swing downward around the fulcrum shaft 42.

[0070] When the stair-climbing wheelchair switches from a stair-walking posture to a flat-ground walking posture: the tilting pivot 52 rotates in the opposite direction, the return spring 14 contracts and pulls the track frame 4 to swing upward around the pivot axis 42 until it returns to its original position;

[0071] Furthermore, the downward pressing cam 53 is recessed to form an arc-shaped limiting part for engaging with the outer circumference of the follower wheel 46; when the stair-climbing wheelchair switches to a flat-ground walking posture, the follower wheel 46 is fully engaged with the limiting part to complete the posture reset.

[0072] Even better, the protrusion and the limiting part have an arc-shaped transition structure, making the posture switching process of the stair-climbing wheelchair smooth and reliable.

[0073] In one embodiment, a drive rod 51 is fixed on the tilting shaft 52; the cylinder body of the tilting electric cylinder 5 is rotatably connected to the drive rod 51, and the telescopic part of the tilting electric cylinder 5 is rotatably connected to the chair frame 1.

[0074] When switching postures using the stair-climbing wheelchair, the tilting electric cylinder 5 extends, and while the swing arm 31 rotates and tilts, the lower end of the track frame 4 swings downwards. This results in high posture switching efficiency. Furthermore, there is no need for a separate mechanism to drive the track frame 4 to swing; the tilting electric cylinder 5 alone can simultaneously complete the swinging of the track frame 4 and the swing arm 31, simplifying the overall structure and reducing manufacturing costs.

[0075] As one embodiment, both the front wheel 2 and the rear wheel 3 of this utility model can be used as drive wheels, and those skilled in the art can make adaptive settings according to specific product performance requirements.

[0076] In summary, this invention provides a low-resistance track assembly that bears the track load by arranging closely spaced load-bearing wheels within the track frame. This transforms sliding friction into rolling friction, significantly reducing the track's driving resistance. The coefficient of friction is reduced by over 80%, allowing the same motor to drive a larger load. The load-bearing wheels have a small diameter and are densely arranged, with minimal gaps between adjacent wheels. When the track presses against sharp protrusions such as steps, the inward deformation of the track cannot enter these gaps, preventing it from getting stuck between the load-bearing wheels. This invention also provides a stair-climbing wheelchair.

[0077] Of course, there may be other embodiments of this utility model. Without departing from the spirit and essence of this utility model, those skilled in the art can make various corresponding changes and modifications based on this utility model, but these corresponding changes and modifications should all fall within the protection scope of the appended claims of this utility model.

Claims

1. A low-resistance track assembly, characterized in that, The system includes a track frame; the track frame includes two opposing frame plates; each end of the track frame is provided with a drive pulley and a driven pulley; the drive pulley is rotatably sleeved on a drive shaft, and the driven pulley is rotatably sleeved on a driven shaft; the ends of the drive shaft and the driven shaft are respectively provided on the frame plates on their respective sides; a track is wound between the drive pulley and the driven pulley. Multiple load-bearing rollers arranged along the conveying direction of the track are rotatably disposed between the two frame plates; the rolling of the load-bearing rollers abuts against the inner surface of the track located below them; the diameter of the load-bearing rollers does not exceed 15mm.

2. The low-resistance track assembly as described in claim 1, characterized in that, The difference between the center distance of two adjacent load-bearing wheels and the diameter of the load-bearing wheel shall not exceed 1 mm.

3. The low-resistance track assembly as described in claim 1, characterized in that, The load-bearing wheel is a bearing, and its inner ring is fixedly sleeved on the load shaft; the two ends of the load shaft are fixed on the frame plate on the corresponding side.

4. The low-resistance track assembly as described in claim 1, characterized in that, The inner surface of the track is provided with a plurality of inner protrusions at equal intervals; the center of each inner protrusion is provided with a notch structure, and the notch structures of each inner protrusion together form a limiting wheel groove for accommodating the load-bearing wheel.

5. The low-resistance track assembly as described in claim 4, characterized in that, The outer surface of the track is provided with multiple protruding strips at equal intervals.

6. The low-resistance track assembly as described in claim 5, characterized in that, The inner and outer protrusions on the inner and outer surfaces of the track are arranged opposite each other.

7. The low-resistance track assembly as described in claim 1, characterized in that, The track frame has a bent structure; the concave part of the bent structure is provided with a pressing wheel that presses against the outer surface of the track; the convex part of the bent structure is provided with a redirecting wheel that rolls against the inner surface of the track.

8. The low-resistance track assembly as described in claim 1, characterized in that, The driven pulley is connected to a tension adjustment assembly mounted on the outer wall of the frame plate; the tension adjustment assembly includes a support block fixed on the outer wall of the frame plate and an adjustment block slidably mounted on the outer wall of the frame plate; the adjustment block is threaded with an adjustment bolt; the support block has a threaded hole, and the bolt head of the adjustment bolt abuts in the threaded hole. The frame plate is provided with adjustment holes, and the driven shaft passes through the adjustment holes and is fixed on the adjustment block.

9. A stair-climbing wheelchair, having a flat-ground walking posture and a stair-step walking posture; comprising a chair frame, wherein a seat and a backrest are provided on the chair frame; two front wheels are installed at the front end of the chair frame; a tilting pivot is provided on the chair frame; a swing arm is fixedly connected to each end of the tilting pivot, and a rear wheel is installed on the swing arm; the chair frame is also equipped with a tilting electric cylinder for driving the tilting pivot to rotate in the forward and reverse directions; characterized in that, The chair frame is equipped with two sets of inclined low-resistance track assemblies as described in any one of claims 1 to 8; a stair-climbing motor for driving the two tracks to rotate synchronously is also installed between the track frames of the two low-resistance track assemblies.

10. The stair-climbing wheelchair as described in claim 9, characterized in that, The two track frames extend downwards at one end into the space between the two front wheels; The chair frame is equipped with a fulcrum shaft, and both track frames are rotatably connected to the fulcrum shaft; the lower end of each track frame can reciprocate around the fulcrum shaft; specifically: When the stair-climbing wheelchair switches from a flat-ground walking posture to a stair-walking posture, the lower end of the track frame swings downward. When the stair-climbing wheelchair switches from a stair-walking posture to a flat-ground walking posture, the lower end of the track frame swings upward to return to its original position. Two downward pressing cams are fixedly sleeved on the tilting shaft; the track frame is provided with a follower wheel for rolling contact with the downward pressing cam on the corresponding side; a return spring is connected between the track frame and the chair frame; the downward pressing cam has a protrusion; The stair-climbing wheelchair switches from a flat-ground walking posture to a stair-step walking posture: the tilting pivot rotates, the protrusion of the downward pressing cam contacts the follower wheel, causing the track frame to swing downward around the pivot axis; When the stair-climbing wheelchair switches from a stair-walking posture to a flat-ground walking posture: the tilting pivot rotates in the opposite direction, the return spring contracts and pulls the track frame to swing upward around the fulcrum until it returns to its original position.

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