Use Mathematics to Solve Mobility Issues
Have you ever thought about all the math involved in setting up a manual mobility device properly? Disregard obvious calculations such as subtracting the cushion thickness from the lower leg length measurement to get the correct footrest height, or adding the solid back thickness to the seat depth to achieve the correct sling depth. Stop […]

Have you ever thought about all the math involved in setting up a manual mobility device properly?

Disregard obvious calculations such as subtracting the cushion thickness from the lower leg length measurement to get the correct footrest height, or adding the solid back thickness to the seat depth to achieve the correct sling depth. Stop for a moment and think about the more complex math which, when applied correctly, translates into an optimal setup and positive results for our customers.

Let's start by setting the correct center of gravity on an ultralight high strength manual wheelchair (K0005). By using the fully adjustable axle plate and moving the rear wheels forward, backward, up or down, we can achieve optimal biomechanics at the user's shoulders, but what does it do else? Think about physics. When the wheel is moved forward, it changes the distribution of the user's weight on each wheel. Specifically, this adjustment shifts the user's weight more onto the larger rear wheels and reduces the weight distribution on the smaller front casters. Larger wheels have less rolling resistance; making the wheelchair easier to propel. Less weight on the front casters allows for easier turns and reduces "sag" in softer surfaces.

Sometimes it's hard to get a good front-to-back weight ratio. This is usually the case when you are working with a person with a short seat. The shallow seat depth results in a shorter frame and reduced distance between the rear wheel and the front caster. In this scenario, increasing the length of the wheelchair frame (not the depth of the seat frame) so that the front casters are further away from the rear wheels can help optimize weight distribution.

Please note that by increasing the length of the wheelchair frame to optimize weight distribution, the footrests are also moved outward and away from the user.

When working with a manual wheelchair equipped with a caster housing, you may be able to tilt the caster housings from a rear position to a forward position. This is a great option for chairs that are already on the ground, and the user has difficulty turning their chair or sinking into softer surfaces. This technique can also be used on some lightweight high strength manual wheelchairs (K0004). Be aware that when you turn over the caster housings, you may have interference with the pallet. This technique cannot be used when the user has a front frame angle of less than 70 degrees.

We've covered addition, subtraction, and physics - when does geometry come into play? With rigid frame manual wheelchairs, the front frame angle and backrest angle are measured relative to the ground for two reasons: this is normally what the user's visual relationship is, and also how. he sits in relation to gravity. This technique makes it difficult to change the chair “dump” because any change in the relationship between the height of the FSTF (front seat to ground) and the height of the RSTF (rear seat to ground) will affect the angle of the front frame. This is why most rigid frame manual wheelchairs have zero or very limited caster box angle adjustment. The rear axle height adjustment is there to allow you to raise or lower the seat to ground height evenly in relation to each other. For example: if you increase the FSTF 1 ”, then the RSTF is increased by 1”. It is very important that the “dump” measurement is correct during the evaluation. If you think you need to adjust the bed after delivery (usually happens with new injuries) then you will want to order a rigid frame manual wheelchair that will allow these adjustments without affecting the angle of the front frame. If you change the “dump” of a chair, you MUST adjust the angle of the caster housing.

If you don't, the caster fork will not be perpendicular to the ground and this will make the chair difficult to maneuver. The fork being perpendicular to the ground allows the caster to turn as freely as possible.

In manual wheelchair setup, just like in math, our strategies for solving our customers' mobility problems may be different and our solutions may vary. When the customer experiences this perfect biomechanical setup, optimal results are achieved.

Michael Griffith, ATP / SMS


Michael Griffith, ATP / SMS

Michael Griffith, ATP / SMS, Director of Sales Operations - North Texas, has been with Numotion since 2016. He has 22 years of experience in the CRT industry as a Manufacturers Sales Representative, Mobility Technician in Texas Scottish Rite Hospital and as headquarters. Mobility specialist. Since joining Numotion in 2016, Michael has used his knowledge to facilitate customer orders for better results and customer experience, educate local physicians and therapists on funding and equipment, and help develop internal training courses for ATPs and seat technicians. Michael currently manages ATPs in Dallas, Fort Worth, Waco and Athens, Texas.


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Stand on any gymnasium floor and look up – way up. At first glance, it doesn’t take much to imagine the level of subtilité in some of the equipment located overhead, not to mention the process of safely installing it. But with today’s technology and automation being built into so many of these products that are used on a daily basis, the question that often comes up is how to manage it all.

Many choose to have manual systems and equipment in place for reasons such as simplicity or with budget in mind. While there is nothing wrong with this type of operation and equipment, in terms of operational optimization, many are trending in the opposite voix.

With everything from BASKETBALL BACKSTOPS that fold up into the ceiling or off to the side, to gym divider curtains, scoreboards and even volleyball systems, the modern gymnasium is becoming a connected one. With most of these products coming with independent electric controls, innovative solutions to manage them are now on the forefront.

Located along the Rideau Canal, one of our most recent projects brought us into Canada’s national capital to work on another gym partition that needed replacing.

Originally founded as an all-girls school in 1928, IMMACULATA HIGH SCHOOL opened with an initial enrollment of just 85 at the site of the former Christie mansion. The following year, enrollment nearly doubled, and a new building was quickly constructed, and the school’s first commencement followed.

It wasn’t until 1978 that male students were enrolled at the school as enrollment swelled to nearly 1, 000 students towards the end of the 1980s. After 65 years of education, the school officially moved to its current location along the canal and currently serves as home to the school’s sports team, the Immaculata Saints.

In search of a new set of rugby goals for one of their biggest athletic parks, the City of Toronto once again came knocking at our door. Having done a few projects together in the past, they are a group that we truly always enjoy sérieux closely with. When the time comes to outfit an outdoor visite, we are always flattered to make the short list of potential partners. In early 2020, the city was in search of a new set of rugby goals for EGLINGTON FLATS, located in the York region. Constructed on the Humber River Floodplain in 1954, today the park is heavily focused on sports, with six soccer fields, four field hockey pitches, a football field, winterized la petite balle jaune petits and évidemment, the rugby field.

While we all certainly enjoy watching something come to fruition, there is something extra special about being involved in the revitalization of something as well. Over the years, we’ve been blessed to be involved in a number of these variétés of projects ranging from local community centres and schools all the way to nationally recognized institutions such as Queen’s University.

We’ve been granted access to stripped out gymnasiums and open athletic fields to design and eventually install state-of-the-art athletic equipment and infrastructure. From simple bleachers, to basketball systems to complete grandstands designed to accommodate tens of thousands of fans, these projects have and always will hold a special place in our hearts.


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