Components of a Mobility Scooter

As mobility scooters have developed over the years, features have changed and options have been extended. However, all models of mobility scooter share a common set of components and characteristics. The main shared components of mobility scooters are outlined below:

Base Unit - The base unit is basically the body of the disabled scooter. Generally it consists of a steel, aluminum, or composite frame with a fiberglass or composite floor to support both the feet and the batteries. The base unit also tends to assert the comfort and safety of the rider. When evaluating a mobility scooter, it is important to be positive that the base can accommodate the needs of the user riding it. The floor of the electric scooter should provide enough space to comfortably support the feet at a natural angle, and the overall dimensions should permit the controls to be easily reached, and just as easily manipulated.

Anti-tip wheels should be included as part of the frame to help support and stabilize an electric scooter. On front-wheel drive units, anti-tip wheels are often found just behind the front wheel because they don't generally have enough power for steep inclines. Because most rear-wheel drive mobility scooters are intended to be used over rougher terrain, they are usually equipped with rear anti-tip wheels to support the eletric scooter on hills. Side anti-tip wheels are sometimes offered as options. It is important to note that anti-tip wheels installed laterally may cause the rider difficulties on curb cuts and ramps.

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Drive Train, Brakes and Power System - The drive train is an integral part of an electric scooter's base unit and determines whether the scooter is front-wheel or rear-wheel drive. Front-wheel drive is usually found on smaller mobility scooters, ones designed to be used mostly indoors or outdoors on flat, paved surfaces. The motor of a front-wheel drive mobility scooter is located just over the front wheel of the machine, and drives only that wheel. Because of the motor and wheel configuration, front-wheel drive scooters tend to be "direct-drive" units, removing the need for chains and belts. However, this also means that the front wheel is responsible for pulling the entire weight of the disabled scooter, and the rider. As a result, these types of mobility scooter have a smaller capacity to enable their rider to handle uphill or rougher terrain. This is increased further by the fact that front-wheel drive scooters generally have smaller motors, resulting in their posessing a shorter range, slower speed and less power, and quite importantly, a smaller weight capacity for the rider of the electric scooter. However, these same limitations are responsible for the most redeeming features of the mobility scooters; they are usually smaller and more manoueverable than the rear-wheel drive electric scooters. Similarly they may well be easier in general to take with you on airline flights, in your car or on the bus etc.

Rear-wheel drive mobility scooters are powered by motors that are connected the scooter's rear axle, by any one of a chain, belt, transaxle unit, or some combination of the afore-mentioned. Because the electric scooter is being powered from behind by the rear wheels, the effect is that a rider is pushed with a rear-wheel drive mobility scooter, rather than pulled as is such with the front-wheel models. The combination of the weights of the rider, motor and batteries create a generally superior traction than that of a fron-wheel drive disabled scooter. Obviously the ability to climb hills is decreased slightly with the rear-wheel drive mobility scooters, as the weight ratio is shifted to the back of the machine. Mobility scooters with a front-wheel drive mechanism will enjoy a faster top speed, a longer range between battery charges, and a larger weight capacity for the user. The rear-wheel models will also have a wider wheel base and longer overall length, making them less easy to manouever than their front-wheel drive counterparts, and may be unsuitable for indoor use or transportation.

Neither the mobility scooters horsepower, nor whether it is front or rear wheel drive will automatically determine whether the disabled scooter is powerful enough to meet the requirements of the user. This is usually determined by the torque of the motor. Most electric scooters use permanent magnet motors, some with lower torque than others. Lower torque motors generally provide greater speed on flat, smooth surfaces, while higher torque motors offer more power for climbing hills and negotiating outdoor and off-road terrain. Higher torque motors may make the electric scooter seem slower on flat ground.  When trying out a disabled scooter, it is very important to know how and where it will be used. If you intend to use your electric scooter mainly off road or for going up hills, then it is advisable to look for one with a higher torque motor.

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Brakes – Almost all rear-wheel drive mobility scooters use an electronic or electro-mechanical dynamic, regenerative braking system. This works with the motor by slowing and then stopping the electric scooter when the user releases the controls. When the mobility scooter is stationary, the brakes are engaged which prevents it from moving. When the brakes are applied, the batteries are recharged with the excess power from the motor. As the brakes are only engaged when the disabled scooter is powered, most electric scooters have a clutch on the motor or a lever which manually disengages the brakes.  This puts the mobility scooter in freewheel mode and allows it to be pushed in case of emergency or so it can be moved for storage.

Some models of electric scooter also use disc brakes or disc brakes combined with the braking system explained above. Front-wheel drive disabled scooters are not usually equipped with electronic or electro-mechanical brakes. In this case, a manual parking brake is applied by lever to a rear wheel. Manual parking brakes may also be offered on other electric scooters either as standard or additional extras to provide supplementary braking on hills and inclines.

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Batteries - Most mobility scooters use 12 or 24-volt motors and electrical systems which have one or two 12-volt batteries to power the disabled scooters drive train and controls. Front-wheel drive electric scooters usually have twelve-volt systems and usually require one 12-volt battery, although two six-volt batteries are sometimes used. Some disabled scooter manufacturers offer additional batteries for 12-volt systems which extend the range of mobility scooter, although this does not increase the speed or power. Rear-wheel drive electric scooters generally have two twelve-volt batteries which power 24-volt systems.

Mobility scooter batteries are "deep cycle" batteries, which are intended for electric wheelchairs and mobility scooters.  These generally last for between 12 and 18 months, depending on how they are used, and how often they are charged. Deep cycle batteries such as mobility scooter and powerchair batteries are designed to provide a steady supply of power and need to be discharged and recharged regularly. Automotive and marine batteries are starter batteries, which are designed to provide short bursts of power, and so should never be used for a mobility scooter.

There are three basic types of batteries used with mobility scooters: lead acid (or wet cell) batteries, sealed lead-acid batteries, and gel cell batteries. Lead acid batteries are the least expensive of the three types, but need the most maintenance. As well as being charged regularly, the electrolyte and water levels must be regularly checked, and water added often to maintain the correct levels. As these batteries are not sealed, there is danger of spillage and explosion if the batteries are not handled properly. Despite these potential dangers, lead-acid batteries provide up to six months longer battery life, and up to ten percent greater running time than other mobility scooter battery types.

Sealed lead acid batteries are maintenance-free versions of lead acid batteries. Because they are sealed in cases, they don’t require maintenance, and so the danger of spillage is greatly reduced or eliminated. The cases have air vents to prevent gas build-up that can lead to an explosion.

Gel cell batteries are the most commonly used disabled scooter battery. They are sealed in cases and require no maintenance other than regular charging. Gel cell batteries are the safest of the electric scooter battery types, with no danger of spillage and limited risk of explosion. However, gel cell batteries are more expensive, and might have a somewhat shorter life than other mobility scooter battery types.

The type and size of mobility scooter battery used should be as per the manufacturer’s recommendation. It is also very important that the battery is compatible with the battery charger. Lead acid and gel cell batteries require different types of charger. However dual chargers which charge both types of batteries are also available.

The battery charger is included with the mobility scooter and can either be an on-board internal charger built into the disabled scooter, or an external charger that is totally separate. On-board battery chargers allow the user to recharge the batteries without having to disconnect the battery pack. The disabled scooter battery pack can then be charged overnight whilst the mobility scooter is stored, in a garage for example.  The downside to having the charger on board the electric scooter is that if the charger fails, the whole mobility scooter will need to taken in for repair. Also, the disabled scooter will need to be stored near a mains electricity outlet so it can be charged.

Some electric scooters have an external charger which, depending on the model of disabled scooter, means the batteries can be charged away from the scooter. This is a common feature on lightweight scooters.   As the small lightweight mobility scooters are designed to be dismantled so they can be easily transported and for storage, the battery pack is often removable.  The battery pack can then be recharged away from the mobility scooter.  This means that the rest of the electric scooter can be left in the car for example, and the battery can be charged in the home, or a hotel room.  This avoids having to take the whole disabled scooter out of the car or garage all the time just to recharge it. 

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Wheels and Tyres - The size of a mobility scooters wheels and tyres have a direct affect on its stability and its ability to overcome obstacles. Electric scooters normally have six, eight, or ten-inch wheels, although other sizes are sometimes used. Some electric scooters use the same size wheels for both the front and rear, while others have smaller wheels at the front and larger ones at the rear. Smaller wheels are generally used on front-wheel drive electric scooters which are mainly intended for indoor use. Where and how the disabled scooter is going to be used should, to some extent, determine the size of the wheels and tyres. The larger the wheels are, the more stable the mobility scooter will be. If the disabled scooter is going to be used primarily indoors, then small wheels will be most appropriate.  If the electric scooter is going to be used mainly outside, and on rough terrain, larger wheels and tyres will be more appropriate.  The larger and wider the mobility scooters tyres are, the greater the grip and ability to climb obstacles such as curbs and outdoor terrain will be. Outdoor tyres can make the disabled scooter less easy to drive in confined indoor spaces.

There are several types of tyres are available for mobility scooters. Manufacturers offer a specific type of tyre as standard and sometimes have other types of tyre available as extra-cost options. Pneumatic tyres have air-filled tubes and are similar to those found on cars. Like on a car, the mobility scooters air pressure needs to be checked regularly, and the tyres may need to be replaced if punctured, similar to a car tyre. Mobility scooter dealers can add a special compound before inflating the electric scooters tyres which reduces the risk of the tyres going flat and is known as puncture-proofing. Disabled scooters with pneumatic tyres provide good shock absorption and an improved ride quality when the tyres are properly inflated. Foam filled tyres are similar to pneumatic tyres, but include foam inserts rather than air-filled tubes. These tyres do not deflate and need less maintenance. They can be more expensive to buy than pneumatic tyres and may not offer the same level of comfort. The least expensive mobility scooter tyre type is solid rubber. These tyres require the least maintenance, but provide a lesser amount of shock absorption and are mainly used on indoor mobility scooters.

Other considerations include the tyre colour and the depth of tread. Most mobility scooter tyres are available in black or grey rubber. Black tyres are generally less expensive and have a longer life than grey tires. However, grey disabled scooter tyres are treated to prevent marking and scuffing of floors and walls which is common with black tyres. Tyres are also available with different treads.  The deeper the tread, the greater the mobility scooters grip on surfaces such as mud, gravel, and grass. However the treads attract dirt and debris when used indoors.  Electric scooter tyres with low or no tread don’t suffer from this problem, but should only be used indoors or on smooth paved surfaces.

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Seating - Mobility scooter seats are usually a chair-style seat similar to those on boats. The basic seat is hard plastic or fiberglass, but most models of disabled scooter have a padded-seat. The seat is usually fitted with either vinyl or fabric upholstery. Vinyl upholstery is less expensive, but it is more slippery, and so might not be the best choice for those with posture or balance difficulties. Some higher-specification disabled scooters have a bigger, more comfortable seat, which is also adjustable for height and reach, similar to a car seat.

Until recently, mobility scooters were not available with custom seating or positioning options. More and more electric scooter manufacturers are now offering ergonomically designed seats, lumbar supports, and separate cushions, so that seating options are similar to those of powerchairs. Some disabled scooter manufacturers offer custom-design seat options.

Seats are usually mounted on a post in the centre or rear of the disabled scooter base, and most swivel up to 360 degrees with stops at every 90 degrees to aid getting on and off.  The seat is controlled using a manual lever beneath the seat. Most electric scooters are equipped with a folding seat back and/or a removable seat post for transport or storage. In addition some mobility scooter seats also allow forward and rear adjustment so that the user can find their most comfortable driving position.

A powered seat is another option on some mobility scooters. This system is usually controlled from the control panel on the tiller, and uses battery power to swivel and elevate the seat.  An elevating seat allows the user greater access to cupboards and other items higher up. A powered seat will add to the cost of the disabled scooter but may be worthwhile, depending on needs of the user. Using the powered seat will drain the battery more quickly so the range of the mobility scooter will be reduced and the battery will need to be charged more often.

Some models of mobility scooters have armrests only as an optional extra depending on the model. Others have fixed armrests as standard with flip-up armrests available as an extra. Armrests are usually constructed of metal with padded upholstery, although some armrests feature a rigid plastic base with padded, upholstered inserts. The armrests attach to the underside of the mobility scooter seat, and are fixed on by bolts.  The armrests are adjustable for width so that the user can find their most comfortable seating position.

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Tiller - The tiller assembly houses the mobility scooter handle bars, and contains the controls to drive forward and reverse as well as the horn, light controls where fitted and the battery gauge. Most electric scooters have a tiller specific to that model of disabled scooter, while other manufacturers have different optional tillers. Depending on the model, the controls can include thumb levers, finger levers, loop handles and even joysticks.  Thumb levers are often used as they allow the user to keep both hands on the handle bars. Pressing the lever with the right thumb makes the disabled scooter go forward, and using the left thumb control makes it reverse. The actual lever itself is pivoted in the middle like a see-saw, so that when the forward lever is pressed, the reverse lever can’t be pressed and vice versa. Pressing the lever harder will increase the speed of the mobility scooter in both forward and reverse.  Users will need to have relatively good hand control in order to operate the disabled scooter safely. Finger control levers are also very common and similar to thumb levers, but are operated similar to a bicycle brake, in that the lever is pulled with the fingers, rather than pushed with the thumbs.  This can be a better option for users with limited dexterity such as those with arthritis.

A Delta handle bar can be found on some mobility scooters. This combines a large handle bar and the see-saw like control mechanism. This allows the mobility scooter to be controlled by either pressing with the thumb, or pulling with the hand.  The electric scooter can be driven forwards by the pulling the right hand lever with the hand, which is the same as pressing the left hand lever with the thumb. Some mobility scooter manufacturers may also be able to adapt controls for an extra cost.

The tiller is usually an upright post attached to the front wheel of the mobility scooter. Flexible tillers are also popular, and can be adjusted for both height and position. This allows the user to place the tiller in the most comfortable position while driving the electric scooter, and also allows the tiller to be moved when getting on and off the disabled scooter. The control box with the key lock, battery level indicator and speed controller is usually found on the tiller handlebars.

As the joystick controls the speed and direction, mobility scooters equipped with joysticks generally do not have a tiller. The joystick is usually attached to an armrest or to an armrest, and can be fitted on the right or left hand side.

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Other Features and Accessories - As well as the standard features that you'd expect to find on any mobility scooter (those outlined above), manufacturers offer a variety of additional standard features and optional accessories. Most mobility scooters utilise a key locking system similar to a car for turning on and off the power, thus conserving the battery life and also preventing the mobility scooter's operation by anyone unathorised to use it. Battery life indicators are also very common, and help especially if the mobility scooter is not charged and used every day. Speed controllers are also normally included in all mobility scooters, but may not be available on some of the older models

A wide range of accessories also are offered on most mobility scooters, such as tail lights, horns, crutch and cane holders, front and rear baskets, oxygen carriers, canopies, trailers, headlights, and others. Some manufacturers even offer sidecars to allow an additional passenger on a mobility scooter. As when purchasing a car, options and additional features increase the base cost of any disabled scooter, but all accessories should be weighed up against how much they can actual act as an aid to mobility for the user. At the same time it's important to note that the addition of some options may decrease the battery life, manouevarabiliy and/or travel range of the mobility scooter. At the same time, it should be kept in mind that some options may decrease battery life, maneuverability, and/or travel range.