The structure of a manual wheelchair

Posted by aijj on December 11th, 2020

Compared with electric wheelchairs, manual wheelchairs are not only more affordable, but also suitable for people who take care of themselves and have more mobility. What are the structural components of a manual wheelchair? Manual wheelchairs generally consist of seven parts: push hand, wheelchair frame, wheels, brake device, anti-falling device, seat back and foot pedal, let's look at the detailed introduction next.

Manual wheelchair structure

Manual wheelchairs generally consist of seven parts: push hand, wheelchair frame, wheels, brake device, anti-fallback device, seat back and foot pedal.

1. Big wheels

Carry the main weight. The diameter of the wheel is 51, 56, 61, 66 cm. Except for a few use environment requirements and solid tires, pneumatic tires are mostly used.

2. Small wheels

There are several kinds of diameters of 12, 15, 18, and 20cm. Small wheels with large diameters are easy to overcome small obstacles and special carpets. However, the large diameter makes the entire wheelchair occupies a larger space, making it inconvenient to move. The normal small wheel is before the big wheel, but in wheelchairs used by lower limb paraplegics, the small wheel is often placed behind the big wheel. It should be noted in operation that the direction of the small wheel should be perpendicular to the big wheel, otherwise it may fall over.

3. Hand wheel

Unique to wheelchairs, the diameter is generally 5cm smaller than the large rim. When hemiplegia is driven with one hand, add a smaller diameter for selection. The hand wheel is generally pushed directly by the patient. If the function is not good, it can be modified in the following ways for easy driving:

(1) Add rubber on the surface of the hand wheel rim to increase the grinding force.

(2) Increase the push knob (knob) along the circumference of the hand wheel.

There are the following types of push handles:

① Push the handle horizontally. Used for C5 spinal injury. Therefore, the biceps muscles are healthy, and the hand is placed on the push handle, and the cart can move forward by flexing the elbow. If there is no horizontal push handle, it cannot be pushed.

②Vertical push handle. For rheumatoid arthritis when the movement of the shoulder and hand joints is limited. Therefore, the horizontal push handle cannot be used.

③Bold push handle. It is used for patients with severely restricted finger movement and difficult to make a fist, and also for osteoarthritis, heart disease or elderly patients.

4. Tires

There are three types: solid, inflatable inner tube and tubeless inflatable. The solid type walks faster on flat ground and is not easy to blast and is easy to push, but it vibrates greatly on uneven roads and is not easy to pull out when stuck in a groove the same width as the tire; with a pneumatic inner tube, it is more difficult to push and easy to puncture, but Vibration is smaller than that of a solid one; the inflatable tubeless type will not puncture because of the tubeless tube, and the interior is also inflated and comfortable to sit up, but it is more difficult to push than the solid one.

5. Brakes

The big wheels should have brakes for each wheel. Of course, when hemiplegics can only use one hand, they have to use one-hand brakes, but extension rods can also be installed to control the brakes on both sides.

There are two types of brakes:

(1) Notch brake. This brake is safe and reliable, but more laborious. After adjustment, it can also be braked on slopes. If it is adjusted to level 1 and cannot be braked on flat ground, it is invalid.

(2) Toggle brake. Using the principle of lever, brake through several joints, its mechanical advantage is stronger than notch brake, but it fails faster. In order to increase the braking force of patients, extension rods are often added to the brakes, but this rod is easy to damage, if not checked frequently, it will affect safety.

6. Seat

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

7. Seat cushion

To avoid pressure sores, pay attention to the cushions. It is possible to use eggcrate or Roto cushions as much as possible. This cushion consists of a large plastic with a large number of nipple-shaped plastic hollow columns with a diameter of about 5cm. All are soft and easy to move. After the patient sits on, the pressure surface becomes a large number of pressure points, and the patient moves slightly, the pressure point changes with the movement of the nipple, so that the pressure point can be continuously changed to avoid frequent pressure on the same The site causes pressure sores. If there is no such cushion, a layered foam plastic should be used, the thickness of which should be 10cm, the upper layer is 0, 5cm thick high-density polyurethane foam, and the lower layer is medium-density plastic with the same properties. High-density ones are strong, and medium-density ones are soft and comfortable. In the sitting position, the ischial tuberosity bears great pressure, often exceeding the normal capillary end pressure by 1 to 16 times, which is prone to ischemia to form pressure sores. In order to avoid excessive pressure here, often dig out a piece of mat on the corresponding place to make the ischial tuberosity overhead. When digging, the front should be 2 and 5 cm before the ischial tuberosity, and the side should be 2, 5 cm outside the tuberosity. The depth is about 7,5cm. After digging, the cushion is in a concave shape, and the gap is behind. If the above cushion is used to add an incision, it can be quite effective to prevent pressure sores.

8. Foot rest and leg rest

The leg supports can be of the type that spans both sides, or the two sides are separated. Both of these supports are ideal for swinging to one side and detachable. You must pay attention to the height of the foot rest. If the footrest is too high, the angle of hip flexion is too large, and the weight will be added to the ischial tuberosity, which is easy to cause pressure sores.

9. Backrest

The backrest is high and low, and can be tilted or not. If the patient has better balance and control of the torso, a low-back wheelchair can be used to enable the patient to have greater mobility. Conversely, choose a high-back wheelchair.

10. Armrest or arm rest

Generally 22,5~25cm higher than the seat surface, some arm rests can be adjusted in height. A lapboard can also be placed on the arm rest for reading and dining.