Structure of wheelchair
Ordinary wheelchair is generally composed of four parts: wheelchair frame, wheel, brake device and seat. The following is a brief description of the functions of the main components of wheelchair.
1. Large wheels bear the main weight. The diameters of wheels are 51, 56, 61 and 66 cm. Pneumatic tires are commonly used except for a few solid tires which are required by the environment.
2. Small wheels are 12, 15, 18 and 20 cm in diameter. Large wheels are easy to cross small obstacles and special carpets. But the large diameter makes the space occupied by the wheelchair larger and the movement inconvenient. Normal wheels are in front of big wheels, but wheelchairs for paraplegics of lower limbs often put small wheels behind big wheels. In operation, it should be noted that the direction of the small wheel is best perpendicular to that of the large wheel, otherwise it is easy to topple.
3. Handwheel rings are unique to wheelchairs. The diameter of handwheel rings is generally 5 cm smaller than that of large wheelchairs. When hemiplegia is driven by one hand, a smaller diameter is added for selection. Handwheel rings are usually driven directly by patients.
4. There are three types of inflatable tyres: solid, inflatable and tubeless. Solid type walks faster on flat ground and is not easy to blast and push, but it vibrates heavily on uneven road and is not easy to pull out when it is stuck in the ditch of the same width as the tire; inflatable inner tube is more difficult to push and puncture, but its vibration is smaller than that of solid inner tube; inflatable inner tube without inner tube will not puncture, and it is also inflatable and comfortable to sit, but it is more difficult to push than solid inner tube.
5. Braking wheels should have brakes on each wheel. Of course, if a hemiplegic can only use one hand, he has to use one hand to brake, but an extension rod can be installed to control the brakes on both sides. There are two kinds of brakes:
(1) Concave brake. This brake is safe and reliable, but more laborious. After adjustment, it can also be braked on the slope. If it can not be braked on the flat ground when it is adjusted to level 1, it will be invalid.
(2) Elbow brake. By using the lever principle and braking after several joints, its mechanical advantage is stronger than that of concave brake, but its failure is faster. In order to increase the braking force of patients, an extension rod is often added to the brake, but the rod is easy to be damaged. If not checked frequently, it will affect the safety.
6. The height, depth and width of the chair seat depend on the patient's body shape, and the material quality also depends on the disease type. Generally, the depth is 41, 43 cm, the width is 40, 46 cm, and the height is 45, 50 cm.
7. Seat cushion is an indispensable element in order to avoid pressure sores. The choice of cushion should also be highly noticed.
8. Foot bracket and leg bracket can be transverse two-sided or two-sided separated brackets, both of which are ideal for swinging to one side and removable. Attention must be paid to the height of the footrest. If the foot bracket is too high, the hip bending angle is too large, and the weight is more added to the ischial tubercle, which is easy to cause pressure sores.
9. Back-to-back can be divided into height, inclinability and non-inclinability. If the patient has a good balance and control of the trunk, a wheelchair with a low back can be chosen to make the patient have a greater range of motion. On the contrary, high-backed wheelchairs should be chosen.
10. Arms or brackets are generally 22.5-25 cm above the seat surface. Some brackets can adjust the height. It can also be mounted on the arm bracket for reading and dining.
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