by Takashi Yogi
Please use this information with discretion because it may not apply to all people and in all situations. If in doubt, consult your equipment manufacturer. Do not attempt to change equipment yourself because serious injury may result. Always consult with a professional technician or therapist before making any changes in equipment or use.
The first decision to be made is choosing a folding frame or rigid frame. Folding frames are the traditional type with an X brace in the middle that allows the frame to fold sideways. The folding process is simple, but the folded wheelchair is often bulky and heavy, and most users cannot load this type into a car without assistance. Newer versions of the folding frame are somewhat lighter than the old chrome steel models, but the folding frame is usually heavier than a rigid frame. This is because the folding frame requires more parts and usually have heavier footrests. Most folding frames have swing away footrests, which makes transfers easier for users who have difficulty transferring. One disadvantage of the folding frame is that the frame is not as strong as a rigid frame. Since many of the joints in a folding frame must move in order to fold, they are subject to wear and stress. These joints move when the chair is pushed and waste some energy. These joints are also difficult to keep in proper alignment. Therefore a folding frame is less efficient than a rigid frame.
Most rigid frames use welded joints for the body of the wheelchair. Usually only the seat back folds down for transport. The wheels have quick-release axles that allow the wheels to be removed easily for transport. Many paras are able to load a rigid-frame wheelchair into a car without assistance. The user first transfers to the car seat, folds the seat back down, removes the wheels, and finally lifts the chair across into the passenger seat. The wheelchair should be secured with the seatbelt. Most rigid frames are made of lightweight aluminum (10 - 20 pounds), so lifting the frame without wheels is fairly easy. The footrests of a rigid frame are usually a simple bar that goes across the front with a platform for the feet. The footrest bar acts as part of the frame structure. A few rigid frames have flip-up footrests, either individual or a latching bar with two footrests attached. In summary, a rigid frame is designed for efficiency and lightness. It is a good choice for users who want to be active and can transfer easily.
Footrest choices include angle and taper. The angle is measured from the horizontal, viewed from the side. A 70- degree angle is usual, but some users are more comfortable with feet elevated slightly using a 60-degree angle. Sport users will often use 90 or greater angle to get the legs out of the way. Elevating legrests provide variable angle, but are very heavy and are used when the legs need to be raised to aid circulation or when the user has difficulty keeping knees bent. Tapered footrests are tapered vertically viewed from the front, and they bring the feet together at the bottom to provide more turning clearance. Some users with limited flexibility in hip and knee joints may be uncomfortable using tapered footrests
To select the wheels, one needs to pick the type of tire first. See the section on tires. The next choice is spoked wheels or composite. Spoked wheels are usually lighter, but somewhat more fragile and require more maintenance with heavy use. Composite wheels tend to wear out at the bearing mountings. The next choice is the camber of the wheel, which is the angle of the wheel from the vertical as viewed from the front. Zero camber provides the narrowest wheelchair width. Increasing the camber increases the width at the bottom of the wheel and decreases the width at the top. This provides more stability and easier turning. It also can make it easier to push the wheelchair since the handrims are more easily reached. The decrease in top width may require moving the wheels outward to clear the body. The increased width produced by camber is the main disadvantage. The increase in wheelchair width with camber (24" wheels) is as follows: 3 degrees --- 1.3", 6 degrees --- 2.5", 9 degrees --- 3.8", 12 degrees --- 5.1". So most ordinary users select zero or 3 degree camber. Greater camber is reserved for sports.
Handrim choices are size, material, and coating. The overall diameter affects propulsion. Large diameter is good for ease in uphill climbs, while smaller diameter is good for racers who want high speed on the flat. Some users grab the tire and the handrim to get additional leverage to get up ramps. One needs to use gloves to grab the tire because it is dirty and there may be sharp objects caught in the tire. Large diameter tubing can make it easier to grab the handrim. Coated handrims are easier to grab, but can be hard to brake on downhills because the hands get hot, even with gloves. Plastic coatings are easily damaged and then become uncomfortable to use. One solution is a coating called Duracush, which uses a foam rubber layer covered by a tough plastic skin. It provides good grip, durability, and more tolerable performance on downhills.
Wheel locks come in two types, side-mounted and under- seat. The side- mounted type is easy to operate, but one has to be very careful not to get thumbs caught in the wheel lock when pushing. The under-seat type avoids this problem, but is more difficult to use because it requires reaching under the seat. The easy way to set this type is to move the outer part of the lock first and then set the lock with the inner lever.
Caster wheel size is selected by balancing the ability to turn versus the ability to get over bumps. Three-inch wheels are fine for basketball players who need to turn quickly on smooth floors, but they are terrible for outdoor use. The larger the wheel, the easier it is to get over a bump. But large wheels take more room to turn, are heavier, and can interfere with feet and footrests. One solution is a new lightweight front suspension fork that absorbs the shock of a bump and allows the wheel to ride over the bump. This produces a smooth ride without having to use pneumatic tires.
The front-back balance of the wheelchair is very important. If the rear wheels are too far forward on the frame, the chair and user will tend to tip over backwards. If the wheels are too far backward, much of the weight will be on the front casters, making the chair hard to push and producing a bumpy ride. Excess weight forward can also cause the chair to tip over when it hits a bad bump and can make it difficult to steer across side slopes. Many users are able to get over obstacles such as doorsills by pushing hard just at the bump. This raises the front casters slightly to get over the bump easily. More experienced users can raise the casters off the ground in a "wheelie". These techniques should be tried only with trained supervision because of the danger of tipping backwards. These techniques are useful, and can only be done if the wheelchair is balanced properly. Most lightweight wheelchairs have adjustments for wheel position. The adjustments needs to be done carefully to maintain safety as well as efficiency. Special adapters are available for amputees who require the wheels further back than usual. Anti-tip wheels are available, but are avoided by most active users because they get in the way.
Power wheelchairs come in various drive types: rear-wheel drive, front-wheel drive, and mid-wheel drive. Rear- wheel drive is the traditional type that is readily available. Front-wheel drives are becoming more common and provide tighter turning than rear-wheel drives. Mid-wheel drives are the latest entry and provide the tightest turning of all. Most front- wheel drives have a slightly lower top speed than rear-wheel drives because of the tendency of front-wheel drives to turn too readily at high speeds. Mid-wheel drives have a tendency to rock when stopping and starting. Mid- wheel drives have caster wheels in the rear and an extra set of anti-tip wheels in front. The extra front wheels may limit the use of mid-wheel drives on uneven ground.
Motor drive systems use either gears or belts to couple the motor to the wheel. Some use both gears and belts. Belt drives can be very quiet, but generally require more maintenance. Modern gear drives are fairly quiet and low-maintenance, but do wear out and get noisier in the process.
Power wheelchair frames vary in ruggedness. The low- priced models have light frames that are suitable for primarily indoor use. They quickly break down if used much on streets. Frames crack, front forks bend, and motors wear out rapidly when these are pushed beyond their design limits. The latest high-priced models are a great improvement over the old models in ruggedness and reliability. Frames are designed for the weight load instead of being manual wheelchair frames with motors and batteries tacked on. Some have spring suspension, which improves the ride tremendously and allows travel over uneven ground.
See the section on tire selection for information on selecting tires for power wheelchairs.
Power wheelchairs are available with power tilt or recline or both. The tilt feature tilts the entire seat assembly and footrests together, usually up to 45 degrees. The recline feature tilts the seat back backward usually to nearly flat and raises the legrests up to horizontal separately. Both of these features are used to provide independent pressure relief for a user. This is important for the prevention of pressure sores.
Wheelchair batteries are different from car batteries because they are used in a different way. A car battery's main function is to start the engine. At other times, it is loafing along, constantly being charged by the alternator. A wheelchair battery is usually charged once a day and must supply large amounts of electricity while it is running. So wheelchair batteries must be a special type called deep-cycle. This means that the battery can be almost completely discharged without damage to the battery. If a car battery is used for a wheelchair, it will soon fail.
Wheelchair batteries will last longer if they are kept as close to full charge as practical. They are unlike the small nickel- cadmium batteries that need to be run down occasionally to preserve their full capacity. Most users need to charge the batteries every night to keep a full charge. Modern battery chargers are automatic so there is no problem of overcharging. If a wheelchair is used only occasionally, the battery needs to be charged at least once a month, and should be charged whenever it is used during a day.
The life of wheelchair batteries depends on how heavily they are used. Most last about a year. Compare this with the life of most car batteries, which last about 4-5 years. The difference is due to the deep cycling of the wheelchair batteries. Some users who travel mostly indoors can use a battery for 2 years. Anything beyond 2 years of life is rare. The best way to tell whether a battery is getting old is to notice if the wheelchair is getting weak at end of trips that were no problem when the battery was new.
New batteries require about 5 cycles of use and recharging before they reach their full capacity. So don't push a new battery for a few days. Freiler Wheelchair has a special computer battery tester that cycles new batteries for several hours to check them and ensure close to full capacity of the battery when installed. The same tester is used to test the old batteries to make sure that they were really bad.
There are two types of batteries for wheelchairs: wet and gel. Wet batteries require adding distilled water about every two months. Wet batteries can be damaged permanently if the water level falls below the level of the battery plates. Adding water is often quite difficult, even for someone with training and no disability. The batteries are heavy and difficult to reach. So adding water is usually impossible for wheelchair users. We will be glad to do it for our clients, even though MediCare will not pay for this service. If you do it yourself, follow these precautions:
1. Use only distilled water. Tap water has minerals that will damage the battery.
2. Don't overfill the battery. If the outside of the battery is wet, the battery has been overfilled. Fill only to about 1/8" below the ring in the hole. Use a flashlight to see the level clearly. Overfilling the battery will result in leakage of battery acid, which will quickly ruin battery connections. The water level will rise as the battery is charged, so a weak battery with low water level should be filled less than normal.
3. Be careful not to short-circuit the battery terminal with any metal. The sparks can ignite the gas in the battery and cause an explosion. Don't smoke. Be careful not to get battery acid on skin and in your eyes -- use gloves and eye protection.
4. Wipe up any spills and replace the caps tightly.
Gel batteries avoid many of the problems of wet batteries. They never need water. They eliminate corrosion problems. They are much easier to take on an airplane trip because airlines require wet batteries to be removed from the wheelchair and placed in a sealed container. The main disadvantage of gel batteries is that they have about 10 to 20% less capacity than comparable wet batteries. This is usually important only for users who travel long distances. They cost more and MediCare will not reimburse us for the full price, but this is not the user's problem. If you want to switch battery types, make sure that the battery charger is suitable for the type of battery. Many old chargers will not charge a gel battery properly. Most new chargers have a switch to select either type of battery.
Many chargers will not charge a completely dead battery. Some have a button that will allow manually starting the charge cycle. In other cases, a different charger must be used. Charging a battery that has been dead for several months is very difficult and requires several days of charging. The battery may be permanently damaged. So it is best to keep batteries charged, even if they are not being used.
Whenever you plug in the charger, always check that the battery is charging, as indicated by a meter or light. The charger plug is subject to a lot of stress, so be sure that the cord and plug are in good condition.
There is no perfect tire for every purpose and every person. A user must decide what is important and select the tire that has the least undesirable qualities. The factors to consider are:
4. Comfort of ride
The first decision is air or no air. Air tires are light, have excellent ride and traction, and good durability. But many users will sacrifice all these to avoid the bugaboo of flat tires. So they resort to using airless tires. Airless tires come in several forms: solid, inserts, and foam-filled. Inserts are foam rubber tubes that are inserted into pneumatic tires to make them airless. Some tires are too bulky for inserts, and these are filled with foam. Using airless tires on a power wheelchair makes sense for most users, because the extra weight is not a problem. Airless tires are stiffer that pneumatics so the ride is more uncomfortable with airless tires, especially for smaller sizes. Many new power wheelchairs have springs on the rear wheels, so ride is acceptable with airless tires. A reasonable compromise is to use airless tires on the rear of a power chair and pneumatic tires on the front. The pneumatic front tires make it much more comfortable when traveling over rough streets and sidewalks. If needed, one can usually limp along on a flat front wheel by leaning. Another way to get smoother ride is to use suspension forks in front. These are available for some power wheelchairs and a new lightweight version is available for manual wheelchairs.
There have been attempts to solve the problem of flat tires, but none have been very successful. One is to use a thorn- resistant tube. These have thicker rubber on the outside, and will resist small punctures. These should be used for power wheelchairs when available. They are much heavier than regular tubes so they may not be suitable for manual wheelchair users. Another attempted solution is to insert a tough plastic strip between the tube and tire to block punctures. The problem with this is that the strip tends to shift and the hard edge can cut into the tire and cause flats. Another solution is to put a sealer inside the tube to seal punctures. The main problem with this is that the sealer tends to clog the valve and cause leakage. If sealer is used, one must be very careful to check for valve leakage whenever air is added. Sealers only work for small punctures. Another way to use sealer is to carry a can of pressurized tire sealer to use in case of flats. This usually works for small leaks. Make sure that the damaged tube is replaced as soon as possible because this is only a temporary fix.
The gray rubber used for most wheelchair tires wears rapidly. Users who travel a lot on streets might be able to use black rubber tires, which last much longer because the carbon added to the tire makes it much tougher. Unfortunately, black tires are available only in a few sizes, probably because the tire manufacturers sell more tires if they wear out quickly. Black tires may produce slight marks on white floors.
1. Keep tires inflated at the proper pressure. The pressure is always stamped on the tire. Use a hand pump or a small electric pump with a gauge. Do not use a gas station air hose. Wheelchair tires have very small volume and it is very easy to explode a tire. Keeping the tires inflated will increase tire life, decrease rolling resistance, and keep the wheel locks effective.
2. Replace worn tires promptly. Don't wait until the black cords of the tire show. Tires are much less prone to flats if they have adequate tread. Wheel locks will work better with good tires.
3. Check your tires regularly. Sometimes a puncture will cause a slow leak that is not obvious. If you do find a small nail in the tire, leave it in place to seal the leak and get the flat fixed.
Proper wheelchair seating is more than just comfort. Lack of proper seating can lead to poor posture and pressure sores (decubitus ulcers). Selecting the best seat depends on the needs of the user. The best for an active para will probably not suit a quad. The factors to consider are support, pressure relief, weight, and maintenance.
Support in a cushion provides a stable base, which is essential for proper posture. This has to be balanced with pressure relief, which ensures that no part of the body receives excessive pressure. If pressure at a point is high enough to cut off blood flow, the tissue will deteriorate and an ulcer will form. Decubitus ulcers are extremely serious and very difficult to heal, often requiring months of hospitalization. So ulcers need to be prevented, and proper seating is the first defense. Another way to prevent ulcers is periodic relief of pressure by shifting the body. If the user can shift in the seat independently, this should be done frequently. If this is not possible the user needs to be provided with the best seat possible and may need other means of pressure relief such as transfers out of the chair or a power tilt or recline seat. Users need to have their skin checked regularly to spot ulcers. Any signs of problems, such as red skin or abraded skin should lead to corrections, such as more frequent pressure relief or better seating.
The traditional sling seat and back has numerous problems. The sag of the seat tends to rotate the hips inward, and the top of the pelvis tends to slump backwards. There is nothing to prevent sliding forward in the seat, so the user is slumped in the seat with back curved, head leaning forward, and neck bent upward. This seating is not suitable for long-term use. Its only advantages are low cost and the ability to fold easily.
Foam seat cushions have improved lately so that they can provide adequate seating for users with moderate needs. The foam can be contoured to provide a stable posture base. The density of the foam can designed to provide moderate pressure relief. The use of multiple densities of foam can provide both pressure relief and stability. Light weight, moderate cost, and easy maintenance are advantages of foam.
Air cushions can provide excellent pressure relief and are usually prescribed for users who are prone to ulcers. The disadvantages of air cushions are poor support and maintenance problems. The cushions tend to be squishy, especially the thick ones. They can get punctures, and the inflation must be maintained to ensure that they don't bottom out.
Gel cushions can provide more stable support than air cushions and still provide good pressure relief. Disadvantage are that they are heavy and can leak. The gel needs to be mixed periodically to keep hard spots from forming. Gel cushions need to be fitted carefully to ensure that all areas have an adequate thickness of gel.
A new type of cushion uses honeycomb cells of plastic to form a seat that provides good support and pressure relief. It is also light, provides good ventilation of the skin, and is machine washable.
A proper seat cushion requires a proper seat platform. Using a good cushion on a sagging sling seat defeats its purpose. If a flat seat surface is not available, a rigid cushion insert can be used to avoid a sag.
A proper back is part of a good seating system. A rigid back with contoured cushion is best. If this is not possible, at least some support can be added to the lumbar or sacral areas to allow a more upright posture.
1. Keep wheelchair in good condition; don't wait until it falls apart. See section on maintenance .
2. On power wheelchairs, always turn power off before transferring, when using a wheelchair lift, or when on a cliff. One user bumped into the joystick while on a van lift and fell backwards off the lift. Fortunately, he survived to learn the lesson. It's a good practice to turn off power whenever you are not driving the wheelchair. This saves a bit on battery juice and decreases the danger of you or someone else accidentally bumping the joystick. On manual wheelchairs, always set wheel locks before transferring.
3. Don't pull backward on doors or other objects when sitting in a manual wheelchair. A door may suddenly release and you may tip over backwards.
4. Don't put heavy loads on the back of a manual wheelchair. It may make the wheelchair tip over backwards.
5. Don't remove the anti-tip wheels on a power wheelchair. If you encounter an obstacle, the torque of the motor may tip you backwards.
6. Don't let children play with your wheelchair. They should be instructed to never touch your wheelchair controls. Don't let them ride on battery cases or on the footrests; these will break if they do.
7. Use a flag if you ride the streets. Use headlights and flashing taillights if you ride the streets at night. Pick bright colors for wheelchairs.
8. Don't go up or down steep slopes. You may lose control and tip over.
9. Have the programming of your power wheelchair set so that it does not go faster than you can handle, especially in reverse.
10. Beware of caster flutter, which is the rapid side to side motion of the caster. This usually happens at high speed, such as when going downhill. It can throw you forward out of the chair. If your casters flutter, get them fixed.
11. Avoid riding in the rain. Wheelchairs are generally not waterproof, especially the electronics. If the electronics gets wet, the wheelchair may behave erratically. Wheels lose traction when wet, especially with urethane tires.
12. Beware of the effects of radio/TV stations and cell phones on power wheelchairs, especially older models. Turn wheelchair power off before using a cell phone. If anything weird happens while driving, turn off the power immediately.
13. Read the operating manual for your wheelchair and observe all the precautions.
A useful general policy for safety is to prevent accidents before they can happen. Instead of just being more careful, think of ways to prevent problems even if you happen to make a mistake. Instead of being careful not to bump the joystick, turn the power off. Don't use high-speed mode indoors, where a mistake might send you into a wall at full speed. Plan ahead of time for emergencies, such as brake failure on a power chair, a power chair moving by itself, or a manual chair tipping backwards.
These are items that wheelchair users need to check periodically. Any problems should be repaired by a qualified service technician.
See section on care of tires.
See section on batteries.
Front casters wheels and forks
Check that the caster wheels spin freely. If not, the problem may be due to hair and other debris caught in the bearing. The wheel usually must be removed to clean the bearing. Check for noises coming from the bearing; a good bearing should be silent. Caster bearings take a beating because they are so close to the ground and pick up dirt and water. The caster stem bearing that supports the fork pivot should turn easily, but should not be so loose that the caster wheel flutters from side to side at high speed. Check that the stem bearing barrel is perpendicular to the floor. If not, the caster will have difficulty turning. Check that the stem caps are in place; they keep water and dirt out. Check that the forks are not bent.
Glide test for manual wheelchairs
Find a smooth level floor such as in a supermarket. Push the chair and let it glide. It should go a long way in a straight line. If not, bearings may be bad or the wheels and casters may be out of alignment. Listen for noisy bearings. If the rear wheels are cambered with a connecting axle, the axle needs to be adjusted so that the wheels are parallel. Otherwise the wheels will have excessive friction.
Wheel locks and electric brakes
Check manual wheel locks for slippage with tires inflated to the correct pressure. The locks should operate easily. If not, the pivots may need lubrication. The pivots need to be tight enough that the wheel lock stays in place when released. If not, the wheel lock will drag against the tire, resulting in wear and wasted effort. Electric brakes for power wheelchairs need to be checked to ensure that they stop the wheelchair without veering and that they hold on a slope.
Check that the footrests are not bent and are at the proper height. Check that the latches hold securely.
Check that the seat cushion is not bottoming out. The air level in inflatable cushions needs to be checked frequently. Gel cushions need to be massaged periodically to keep the gel from settling into hard lumps. Check cushion covers, especially on air cushions since air cushions will not work without a proper cover. Check sling seats and backs for tears and sags.
Check that rear wheels on manual chairs spin freely without wobble. Check for loose and broken spokes. Check quick release axle pins. They should release easily. The axle pins should be adjusted so that they are slightly loose when in place to ensure that the locking mechanism is fully engaged. Always check that the wheel is locked firmly in place after mounting a wheel.
Electrical problems on power wheelchairs
If you have electrical problems, note which side it affects. If the lights on the joystick box are flashing, note carefully the pattern; they signify an error code, usually by the number of lights or the number of blinks.
Listen for unusual noises coming from the motor or gearbox. Check drive belts for slippage and wear. Check for jerking motion of the chair; this indicates serious problems.
Check that the joystick returns freely to neutral without binding. Check that the seal on the joystick is intact; it keeps dirt and water out. Check that all switches and controls are tightly in place. Check that the joystick clamp holds the joystick firmly in place.
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