Wheelchair structure function

Large wheels

Carry the main weight. There are 51, 56, 61, and 66 cm wheel diameters. Most of them are pneumatic tires, except for a few that use solid tires because of environmental requirements.

Small wheels

There are 12, 15, 18, 20cm in diameter. Small wheels with large diameters are easy to cross over small obstacles and special carpets. However, too large a diameter makes the entire wheelchair take up more space and makes it inconvenient to move around. The normal small wheel is in front of the big wheel, but in wheelchairs for paraplegics, the small wheel is often placed after the big wheel. It should be noted that the direction of the small wheel is best perpendicular to the large wheel, otherwise it is easy to tip over.

Handwheel ring

The diameter of the handwheel is generally 5 cm smaller than that of the large wheel, and when the hemiplegic is driven with one hand, a smaller diameter is added for selection. The handwheel ring is generally driven by the patient directly, if the function is not good, in order to drive easily, there can be changes in the following ways: (1) Add rubber on the surface of the handwheel ring to increase the abrasive force. (2) increase the push handle (knob) along the handwheel ring around. Push the handle has the following kinds: ① horizontal push handle. Used in C5 spinal injury. Therefore, when the biceps muscle is sound, hand on the push handle, by flexing the elbow force can push the car forward. If there is no horizontal push handle, it is impossible to push. ② Vertical push handle. It is used for rheumatoid arthritis when the shoulder hand joint movement is limited. Therefore, the horizontal push handle cannot be used. ③ Thicker push handle. Used for patients with severely restricted finger movements that make it difficult to make a fist, and also for patients with osteoarthritis, heart disease or elderly patients. (Hand crank wheelchair driven by hand crank Bing instead of hand rim)

Tires

There are three types: solid, with inflatable inner tube and tubeless inflatable type. The solid type is faster and less prone to bursting on flat ground and easy to push, but vibrates greatly on uneven roads and is not easy to pull out when stuck in a groove the same width as the tire; the one with an inflatable inner tube is harder to push and easier to puncture, but vibrates less than the solid one; the tubeless inflatable type does not puncture because there is no inner tube and the interior is also inflated and comfortable to sit on, but is harder to push than the solid one.

Brakes

Large wheels should have brakes on each wheel. Of course, if a person with hemiplegia can only use one hand, he can only use a one-handed brake, but he can also install an extension pole to operate the brakes on both sides. There are two types of brakes: (1) notch brake. This brake is safe and reliable, but it takes more effort. After adjustment, it can be braked on the slope, but if it is adjusted to level 1, it cannot be braked on flat ground. (2) Elbow joint brake. Using the principle of leverage, through several joints and then braking, its mechanical advantage is stronger than notch type brake, but failure is faster. In order to increase the braking force of the patient, often add extension rods to the brake, but this rod is easy to damage, such as infrequent inspection will affect safety.
Chair seat

Its height, depth and width depend on the patient's body type, and the texture of its material also depends on the type of disease. The general depth is 41, 43cm, width 40, 46cm, height 45, 50cm.

Seat cushion

In order to avoid pressure sores, a high degree of attention should be paid to the cushion, and if possible, try to use an egg basket (eggcrate) type or Roto cushion, which consists of a large piece of plastic with a large number of papillary plastic hollow columns of about 5cm in diameter, each column is soft and easy to move. This allows the pressure points to be constantly changed, avoiding pressure sores caused by frequent pressure on the same area. If the above cushion is not available, a laminated foam should be used, the thickness of which should be 10 cm, with the upper layer being 0.5 cm thick high-density polyarethane foam and the lower layer being medium-density plastic of the same nature, with the high-density being supportive and the medium-density being soft and comfortable. In the sitting position, the sciatic node is under great pressure, often exceeding the normal capillary end pressure by a factor of 1 to 16, making it easy for ischemia to form pressure sores. In order to avoid excessive pressure here, a piece is often dug out of the mat at the corresponding place to allow the sciatic tuberosity to be hollowed out. When digging, the front should be 2.5 cm in front of the sciatic tuberosity, and the side should be 2.5 cm lateral to that tuberosity, with a depth of about 7.5 cm. After digging, the mat is concave, with the notch at the back.

Foot rests and leg rests

The leg rest can be either across both sides or separated on both sides, both of which are ideal to use the one that can swing to one side and can be removed. Attention must be paid to the height of the foot rest. If the foot rest is too high, the hip flexion angle will be too large and more weight will be added to the sciatic tuberosity, which will easily cause pressure sores there.

Backrest

The backrest can be tall or short, and can be tilted or not. If the patient has good balance and control of the trunk, a wheelchair with a low backrest can be used so that the patient has greater mobility. Conversely, a high backrest wheelchair should be used.
Armrests or arm rests

Generally 22.5~25cm above the seat surface, some armrests can be adjusted in height. You can also set up a lap board on the arm rest for reading and eating.

Skirt guard plate (net)

According to different users, skirt guard board, skirt guard net can be used to prevent the user's skirt or hem from getting caught in the wheel.