Power Wheelchair Measurement Method

Power Wheelchair Measurement Method

The door width of general front door is about 90 cm wide, and the bedroom or kitchen door is about 80 cm wide. Usually the smallest door will be the bathroom door, at only 70-75 cm wide. In order to avoid the problem of not being able to turn, pay attention to the wheelchair width when choosing a power wheelchair.

Overall Width

After the assembled wheelchair is ready for use, measure the distance between the left and right outermost points horizontally.

Overall Height

After the assembled wheelchair is ready for use, measure the vertical distance between the highest point and the floor.

Folded Length

Without using tools, remove all components with just your hands and completely fold or disassemble the wheelchair. Measure the distance from the most front of the chair to the furthest back of the chair.

Folded Width

Without using tools, remove all components with just your hands and completely fold or disassemble the wheelchair. Measure the distance from widest points of the wheelchair from left to right.

Folded Height

Without using tools, remove all components with just your hands, completely fold or disassemble the wheelchair and fold the backrest towards the seat as much as possible. Without the removed parts, measure the height from the floor to the highest point.

Total Mass (Without Battery)

After the wheelchair is equipped with standard equipment, the total weight of the whole wheelchair without batteries.

Mass of the Heaviest Part

Without using tools, after disassembling all the parts of the wheelchair, measure the weight of the heaviest single piece.

Ground Clearance

After removing the detachable wheelchair components such as the anti-tippers and footrests, measure the lowest distance between the main frame and the ground. The distance between the front caster and the ground is usually the lowest.

Minimum Turning Radius, defines the smallest radius for a user to turn around on a wheelchair 360°. Before buying a wheelchair, it is important to check if the wheelchair can be navigated through all the confined places in one’s living environment, such as the elevator. The mid-wheel drive electric wheelchair offers the smallest turning radius, followed by the front-wheel drive and rear-wheel drive.

Minimum Turning Radius

This is the radius of the smallest area in which the wheelchair (WITH an RLG dummy) can be turned for 360° in one constant forward drive with maximum steering effect.

If the wheelchair is equipped with adjustable footrests or anti-tipper, these parts are configured into their most compact position.

A turning radius measured with an RLG dummy takes into consideration not only the wheelchair, but it also covers the feet of the human body, which gives a more realistic and exact measurement to help you evaluate your decision.

Minimum Turning Radius without RLG

This is the radius of the smallest area in which the wheelchair (WITHOUT an RLG) can be turned for 360° in one constant forward drive with maximum steering effect.

If the wheelchair is equipped with adjustable footrests or anti-tipper, these parts are configured into their most compact position.

Minimum Turning Radius, defines the smallest radius for a user to turn around on a wheelchair 360°. Before buying a wheelchair, it is important to check if the wheelchair can be navigated through all the confine places in one’s living environment, such as the elevator in apartments. All else equal, the mid-wheel drive electric wheelchair offers the smallest turning radius, followed by the front-wheel drive and rear-wheel drive.

Minimum Turning Radius

This is the radius of the smallest area in which the wheelchair (WITH an RLG dummy) can be turned for 360° in one constant forward drive with maximum steering effect.

If the wheelchair is equipped with adjustable footrests or anti-tipper, these parts are configured into their most compact position.

A turning radius measured with an RLG dummy takes into consideration not only the wheelchair, but it also covers the feet of the human body, which gives a more realistic and exact measurement to help you evaluate your decision.

Minimum Turning Radius without RLG

This is the radius of the smallest area in which the wheelchair (WITHOUT an RLG) can be turned for 360° in one constant forward drive with maximum steering effect.

If the wheelchair is equipped with adjustable footrests or anti-tipper, these parts are configured into their most compact position.

Reversing Width

When moving through a narrow passage, the wheelchair user must wheel forward, backwards and forwards again to make a 3-point turn to turn 180°. Measure the minimum distance it takes to make a 3 point turn without touching the walls.

Wheelbase

In the forward direction, the distance between the driving wheels and turning wheels at the ground contact point adjacent to the wheels’ axels. For mid-wheel drive chassis, this measurement will include the distances between the front and middle wheel, and the middle and rear wheels.

Front, Middle, and Rear Wheel Track

The Wheel Track is the distance between the floor contact points (measured from the center part line of the tire.) of the left wheels and right wheels.

Seat Plane Angle

Take the horizontal cushion surface as the reference at 0° and measure the angles of the of the seat (back and front).

Sitting in a wheelchair for a long time will cause pressure to concentrate on the hips after a long time. When you ‘Tilt-in-Space’ over 30°, the pressure originally concentrated on the hips will be fully transferred to the back. By ‘Tilting-in-Space’ at a small angle, you can increase the stability of the users sitting position and avoid sliding.

Sitting in a wheelchair for a long time will cause pressure to concentrate on the hips after a long time. When you ‘Tilt-in-Space” over 30 degree, the pressure originally concentrated on the hips will be fully transferred to the back. By “Tilting-in-Space” at a small angle, you can increase the stability of the users sitting position and avoid slipping.

Tilt Angle

Use the horizontal surface of the seat cushion as the reference 0°, measure the angle between the stationary position and the most extreme tilt of the “Tilt-in-Space” seat.

If the seat depth is shorter than user’s thigh length, the user is more likely to lean forward on the chair; if it is too deep, the legs will be blocked by the front edge of the seat, making it hard for the user to sit up straight, causing posterior pelvic tilt and other issues. Generally speaking, an appropriate wheelchair seat depth should be 2-3 cm shorter than the user’s thigh length.

Effective Seat Depth

The effective seat depth is measured from the intersection of the leg reference plane and the seat reference plane to the intersection of the backrest reference plane and seat reference plane. The reference planes are defined by ISO 7176-7.

The word “effective” specifically refers to the measurement method that is based on the ” RLG dummy”.

Compared to “Nominal Seat Depth”, Effective Seat Depth can more accurately simulate the degree of best fit between the human body and the wheelchair.

Nominal Seat Depth

The seat depth is measured from the front end of the seat cushion to the bottom edge of the back cushion (including the gap between the seat and the back cushion).

Compared to “Effective Seat Depth”, Nominal Seat Depth is easy to measure and is mostly used during the ordering process among suppliers.

If the seat depth is shorter than user’s thigh length, the user is more likely to lean forward on the chair; If it is too deep, the legs will be blocked by the front edge of the seat, making it hard for the user to sit up straight, causing posterior pelvic tilt and other issues. General speaking, an appropriate wheelchair seat depth should be 2-3 cm shorter than the user’s length of thigh.

Effective Seat Depth

The effective seat depth is measured from the intersection of the leg reference plane and the seat reference plane to the intersection of the backrest ref plane and seat ref. plane. The reference planes are defined by ISO 7176-7.

The word “effective” specifically refers to the measurement method that is based on the ” RLG dummy”.

Compared to “Nominal Seat Depth”, Effective Seat Depth can more accurately simulate the degree of fitness between the human body and the wheelchair.

Nominal Seat Depth

The seat depth is measured from the front end of the seat cushion to the bottom edge of the back cushion (including the gap between the seat and the back cushion).

Compared to “Effective Seat Depth”, Nominal Seat Depth is easy to measure and is mostly used in ordering process among suppliers.

Effective Seat Width

The word “effective” specifically refers to the measurement method that is based on the “RLG dummy”, which takes into consideration of the density of the human body.

The effective seat width is the distance between the two side guards on a standard line, which is defined at 100 mm from the seat cushion surface and 120 mm from the back cushion surface.

If the wheelchair is not equipped with side guards, measure the distance between the armrests instead. (The standard line of a child’s wheelchair is defined at 60 mm from the seat plane and 72 mm from the back cushion).

Nominal Seat Width

The width of the seat cushion is measured 120 mm in front of the backrest. For some manual wheelchair models, it can be determined by the distance between the armrests.

Compared to “Effective Seat Width”, Nominal Seat Width is easy to measure and is mostly used during the ordering processes among suppliers.

The measurement of Karma’s sling seat and captain seat is the widest distance between the seats.

Effective Seat Width

The word “effective” specifically refers to the measurement method that is based on the “RLG dummy”, which takes into consideration of the thickness of the human body.

The effective seat width is the distance between the two side guards on a standard line, which is defined at100 mm from the seat cushion surface and 120 mm from the back cushion surface.

If the wheelchair is not equipped with side guards, we will measure the distance between the armrests instead. (The standard line of a children ’s wheelchair is defined at 60 mm from the seat plane and 72 mm from the back cushion)

Nominal Seat Width

The width of the seat cushion is measured 120 mm in front of the backrest. For some manual wheelchair models, it can be determined by the distance between the armrests.

Compared to “Effective Seat Width”, Nominal Seat Width is easy to measure and is mostly used in the ordering processes among suppliers.

The measurement of Karma’s sling seat and captain seat is the widest distance between the seats.

When the seat height is too high, it is more difficult for the user to move to the wheelchair by themselves. If the seat height is low it is easier for the user to move but make sure that the distance between the seat surface and the footrests can still accomodate the calf length. The seat height also affects the accessibility of the environment, such as eating at a table and driving etc.

When the seat height is too high, it is more difficult for the user move to the wheelchair by themselves. If the seat height is low it is easier for the user to move but make sure that the distance between the seat surface and the footrests can still accomodate the calf length. Seat height also affects the accessibility of the environment, such as eating at a table, driving by yourself, etc.

Seat Surface Height at Front Edge (with Cushion Foam)

The vertical height of the front edge of the seat surface to the floor, which is the first point of contact between the occupant and the wheelchair.

Function-wise, if the seat to back angle is less than 90°, the stability of the pelvis increases and the user has more control. When the angle is greater than 90°, the occupant can release any pressure on the hips and abdomen. Physically, the adjustment of the seat to back angle can be adapted to users with hip contractures or limited angles to stabilize their sitting posture.

Functional-wise, if the seat to back angle is less than 90°, the stability of the pelvis increases and the user has more control. When the angle is greater than 90°, the occupant can release any pressure on the hips and abdomen. Physically, the adjustment of the seat to back angle can be adapted to users with hip contractures or limited angles to stabilize their sitting posture.

Seat to Back Angle

Using the seat cushion as the reference point of 0°, measure the angle of the back cushion reference plane, that is, the angle between the seat cushion and the back cushion.

Backrest Angle

Using the vertical line of the horizontal plane as the reference point at 0°, measure the angle between the reference point and the back pad.

Backrest Height (with Cushion Foam)

From the surface of the seat cushion, measure the distance to the highest point of the back cushion.

Headrest Height Above Seat (with Cushion Foam)

From the surface of the seat cushion, measure the distance to the midpoint of the head.

Nominal Headrest Height Above Seat (with Cushion Foam)

From the surface of the seat cushion, measure the distance to the top of the headrest.

Everyone has different calf lengths. If the distance from the foot support to the seat is shorter than the user’s calf length, it will raise the user’s knees, increase the angle of the thighs, and therefore concentrate more pressure on the hip-bone area. If the distance from the foot support to seat is longer than the user’s needs, it will cause the user to slide forward and forece them to user their feet for support. This can increase the risk of posterior pelvic tilt or scoliosis in the long term.

Everyone has different calf lengths. If the foot support to seat setting is shorter than the user’s calf length, it will raise the user’s knees, increase the angle of the thigh, and therefore concentrate more pressure on the hip-bone area. If the foot support to seat setting is longer than the user’s needs, it will cause the user to slide forward and use their feet for support. This can increase the risk of posterior pelvic tilt or scoliosis in the long term.

Calf Length
( Footrest to Seat Distance )

The foot support to seat distance is measured from the seat reference plane to footplate. The reference planes are defined by ISO 7176-7.

Leg to Seat Surface Angle

The angle from the seat cushion to the footrests. Calculated from the reference plane of the seat cushion at 0°, and downward is the angle of the calf.

When an occupant rides in a wheelchair, their hands naturally hang down, and the elbows are placed on the armrests. When the elbow is placed on the armrest and the user is in the “shrug” posture, it means that the height of the armrest is too high. If the elbows cannot fit on the armrest pads or they hang in the air, it means that the position of the armrests are too low, which will reduce the support of the shoulders and increase the risk of joint deterioration or dislocation of the user.

When an occupant rides in a wheelchair and their hands naturally hang down, the elbow is placed on the armrest. When the elbow is placed on the armrest and the user is in the “shrug” posture, it means that the height of the armrest is too high. If the elbow cannot fit the armrest pad or theyhang in the air, it means that the position of the armrest is too low, which will reduce the support of the shoulders and increase the risk of joint deterioration or dislocation of user.

Armrest Height

The armrest to seat distance is Measure the vertical distance between the armrest and the surface of the seat cushion., which is defined at 100 mm from the seat cushion surface and 120 mm from the back cushion surface.

Front Location of Armrest Structure

Measure the distance from the backrest to the forefront of the armrest at 680mm high from the ground.