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• Active user wheelchairs are manufactured to be efficient to self-propel, therefore the options available on active user wheelchairs are usually aimed at either being lightweight, or enabling an efficient configuration for self-propelling.
• Reducing the weight of the chair can be achieved either by reducing the amount of material used or by using a lighter material. For example, many active user chairs have a rigid, non-folding design.  Because a folding mechanism uses a lot of additional frame material, rigid chairs will tend to be lighter.  Another example is the use of aluminium, titanium or carbon fibre to construct the frame of the wheelchair, rather than steel.  Minimising the presence or weight of any accessories such as push handles, tool kits and back packs also reduces the weight of the chair as a whole.
• There are many ways in which an active user wheelchair can be configured to make it efficient, or easier to self-propel. As described above, being lightweight will help with increasing the efficiency of an active user wheelchair, but there are many other considerations:
  • Seat size. Having a seat width that is too wide means that excessive shoulder movement is required when self-propelling.  A narrow seat width means the wheels are as close as possible, allowing the shoulders to move  in their strongest, most efficient position.
  • Centre of gravity. Many active user wheelchairs have forward-backward adjustment of the rear wheel position, or can be built with a specific position.  It is essential for most active user wheelchairs to have more weight distribution over the rear wheels, than the front casters.  The rear wheels are larger, have a larger tyre and therefore roll with less resistance.  By moving the position of the rear wheels forward on the frame of the wheelchair, the wheelchair becomes more efficient to roll and to self-propel.  This forward position of the rear wheels has the added benefit of improving the position of the shoulders.  They can move with greater strength and efficiency.
  • Seat height. Many active user chairs can be adjusted or configured with specific front and rear seat heights.  The rear seat height determines the height of the shoulders above the rear wheels.  If the rear seat height is too great, the user is required to straighten their elbows more to reach the rear wheels, reducing the strength and efficiency of the arm and shoulder when self-propelling.
  • Backrest height. Excessive height of the backrest restricts movement of the back and shoulders when self-propelling.  However, backrest height is important in creating a stable sitting position.  Therefore if the backrest is not high enough, self-propelling efficiency is likely to be compromised.
  • Standard brakes are positioned to be easy to operate and close to the tyre.  During forceful self-propelling, the thumb of the user can contact the brake, resulting in injury.  Many active user wheelchairs are therefore fitted with brakes that fold away from the tyre when not in use.
  • The wheels transfer energy from the user into movement of the wheelchair, therefore they are important in maintaining efficiency of the wheelchair.  A well-built, lightweight but strong wheel will transfer a greater proportion of energy than a poorly made, heavy wheel.  Being the widest part of a wheelchair, they need to be able to deal with knocks.  A strong wheel will be able to deal with those knocks, when they are attached to the wheelchair and when they're not. 
  • The major decision when it comes to tyres is between pneumatic and solid tyres.  Pneumatic (air-filled) tyres tend to be lighter than solid tyres.  They also have significantly less rolling resistance, making self-propelling much less difficult.  The downside with pneumatic tyres is there possibility of puncturing.  This likelihood can be reduced with thicker tyre tread, good maintenance, liquid infills inside the tube and avoiding certain places where puncture might be likely.  Learning to replace a tube or having someone else that can do this can be a very useful skill.

• Drive Type
  • There are three main drive wheel configurations available on powerchairs. Drive wheels are those which are attached to the motors.  The motors control the movement of the powerchair, as well as steering and braking.  Powerchair motors have brakes integrated into them, meaning that when the drive is not engaged in movement, the brakes will be activated. 
  • Rear wheel drive. This is the most common configuration.  A rear wheel drive has four wheels in contact with the ground, with the drive wheels at the back.  Rear wheel drives have the largest turning circle out of three described here when compared against comparable chairs.  They have good traction when ascending slopes because of the additional weight of the user that transfers to the rear wheels when travelling uphill.  The compromise is on descents, where reduced weight over the rear wheels produces less traction and less braking capacity.
  • Mid wheel drive. Most mid wheel drive powerchairs have six wheels in contact with the ground. The front two and rear two are casters and the middle two are larger drive wheels.  The main benefit with mid wheel drive powerchairs is their turning circle which is significantly smaller than a comparable rear wheel or front wheel drive.  Because the drive wheels are located beneath the user and in the centre of the wheelchair, it can turn within its own length.  This is often very useful in small environments such as bathrooms and kitchens where large turning circles and three-point turns create difficulty.
  • Another benefit of mid wheel drive powerchairs is the weight distribution over the drive wheels. The drive wheels will tend to bear most of the weight irrespective of whether the chair is being driven uphill, downhill or on the flat.  This means the drive wheels are likely to have good traction in all scenarios, maintaining control and braking capacity.  However, there needs to be sufficient up/down movement of the front and rear casters, relative to the drive wheels.  This movement enables the drive wheels to maintain contact with the ground.  If there is insufficient movement, the possibility of the drive wheels losing contact with the ground is increased.
  • Front wheel drive. This is the least common configuration.  Like a rear wheel drive, a front wheel drive tends to have four wheels in contact with the ground.  The motors are connected to the larger front wheels.  The turning circle of a front wheel drive is slightly less than a comparable rear wheel drive but will tend to be larger than a mid-wheel drive.  Front wheel drives have good traction going downhill but are likely to have reduced traction when travelling up hill. 

• Controls
  • Most powerchairs are controlled with a joystick. This enables the user to control the powerchair in all directions, combining forward or reverse with left or right to create smooth turning.  When the joystick is returned to centre, the chair stops and the brakes are applied automatically.  Speed is controlled by the amount of movement of the joystick in each direction - the further the joystick is moved, the faster the powerchair will go.  This is called proportional control.  Most joysticks are fitted to the armrest of the wheelchair, allowing the user to control it with their hand or fingers.
  • Joysticks can also be fitted to other parts of the wheelchair, enabling control with other parts of the body. Examples could be the chin, lips, head or foot.  Different sizes or joysticks, and the force required to operate them, are available to tailor the joystick to the part of the body being used.
  • For those who find it difficult or impossible to control a proportional control, switched control is also possible. Switched control allows many different combinations of switches or buttons to be used to enable driving.  At a basic level, one switch can control forward movement only with no access to other directions.  Switches can be added to this to enable control of left, right and reverse.  Most powerchairs will have the option of latched or non-latched switch control.  Latched control allows a button to be pressed once and the chair to continue moving in the direction chosen until another button is pressed.  Non-latched control requires a button to be held down to achieve movement in that direction.  Non-latched control is significantly safer and the most common option. 
  • Switches can also be used to operate a scanner control. A scanner is simply a display screen with a direction indicator.  The indicator will highlight or light up each direction, one at a time, in a predictable rotation, enabling the user to select a direction by pressing a single switch.  Used in non-latched mode, when they release the switch, the indicator will start scanning again, giving the user the opportunity to chose a different direction or continue on the same path.

• Leg rests
  • The most common leg rests fitted to powerchairs are swing away. Each leg rest is fitted to the wheelchair on a hinge mechanism.  When unlocked, the hinge enables the leg rest to rotate out to the side, allowing a clear space in front of the wheelchair for transfers or to enable the user to get very close to something in front of them.  A footrest will normally be attached to the end of each leg rests, allowing individual adjustment of the position of each foot.  However a single footplate, spanning the entire width between the leg rests can also be fitted to some powerchairs. 
  • Centre mount footrests can be fitted to mid wheel and front wheel drive powerchairs. A centre mount footrest is fitted to the front, centre of the seat.  It normally enables the user to sit with their knees bent more than with swing away leg rests.  This position reduces the length of the chair as a whole, allowing it to negotiate smaller spaces.  Centre mount legrests can not normally be fitted to rear wheel drive powerchairs because the space between the front casters is not wide enough to fit the footrest. 
  • For below knee amputees, stump supports can be fitted to the legrests as well. This provides a supportive surface for the stump to rest with their knee straight. 

• Armrests
  • Most powerchairs are fitted with armrests. They enable the user to rest their arms on a supportive surface, taking away the muscular effort required to maintain the position of their arms.  This also prevents the weight of the arm pulling the upper body of the user forward or sideways.  Most armrests are height adjustable, allowing multiple heights to be achieved. 
  • There are two main types of armrest - single post and flip back. Single post armrests are attached to the side of the seat frame and need to be removed if the user is transferring sideways to or from the wheelchair.  Flip back armrests can be moved without removing them.

• Headrests
  • Headrests allow the head to be supported, especially when using tilt in space or recline. In both positions, the user's head is likely to fall backward with gravity, therefore it is important to support it in a comfortable position.
  • Headrests also provide some safety when travelling in a vehicle whilst seated in the wheelchair, in a similar way the headrest of a standard car seat would do. It is important to note that a wheelchair headrest is not tested to the same criteria as a car seat headrest would.
  • Some users require additional head support to maintain an upright head position, or to maintain their head in a comfortable position. Additional supports and shaping can be added to tailor the support offered by the headrest.

• Powered seat movements.
  • Electric actuators (using the same principles as those used to control the shovel on earth moving equipment) can be fitted to many powered wheelchairs. The actuators are powered and controlled through the main control system of the wheelchair and enable the user to move specified parts of the seat frame.  The commonly fitted actuators are described below.
  • Tilt in space. Tilt in space tips the seating of the wheelchair backwards (imagine tipping a dining chair onto its back legs) and allows gravity to ‘push’ the upper body of the user against the backrest of the wheelchair.  This enables the user to maintain a sitting position, but with reduced muscular effort.  Tilt in space also helps with pressure relief by re-distributing weight bearing from the cushion to the backrest.  For users using a hoist to transfer to their wheelchair, tilt in space can make this transfer easier, allowing the angle of the seating to match that of the user in their hoisted position.  For other users, tilt in space enables them to adjust their own position, using gravity to assist them slide back over the cushion.
  • Recline is an adjustment of the seat to back angle only, in the same way a backrest can be reclined on a car seat.  Recline needs to be used with caution because it can often cause the user to slide forward over the cushion.  However it can be useful for some users to manage pain by enabling them to shift their position.  For other users, it can make hoisted transfers easier, by giving carers more space to insert or remove the sling.  When combined with tilt in space, recline can assist with pressure relief, allowing more weight to be re-distributed from the cushion to the backrest.
  • A riser, as the name suggests, simply raises the seating unit of the wheelchair directly upwards.  For some users, this enables them to complete standing transfers by giving them a higher surface to stand from.  For others, it enables them to reach objects that would normally be too high.
  • Both centre mount and swing away leg rests (described above) can have actuators fitted to control their movement.  A centre mount leg rest often has movement in two planes; elevation which moves the footplate forward, straightening the knees, and a direct up and down movement that changes the distance between the seat surface and the footplate.  Sometimes, these movements can be combined.
  • Swing away leg rests can also have elevation. Some are fitted with an additional feature that extends the length of them slightly whilst they elevate, referred to as articulation.  This prevents the knees of the user being lifted off the cushion during elevation. 
  • Elevating leg rests are often fitted to control swelling of the legs, however simply elevating the legs achieves very little improvement - the legs continue to remain the lowest part of the body for fluid to accumulate. Combined with tilt in space and recline however, the legs can be raised high enough to encourage a reduction in swelling.  This can be an uncomfortable position, therefore many users will opt to transfer to their bed, where they can comfortably raise their legs whilst lying down. 

Dear John

I hope that you are well.

I had a call from my client today saying how impressed that he was with you yesterday. He found it really helpful so thanks for that.  He wants to recommend you to a friend of his.

Thanks once again

JC - Anglia Case Management