Calculating torque on a wheelchair

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In summary: However, when considering the rolling motion of the wheels, you will need to take into account the rolling resistance, which is typically around 0.01-0.03 times the weight of the system. This will affect the torque needed to move the wheelchair uphill. Additionally, it is important to consider the efficiency of the gear reducer in order to accurately determine the torque required.In summary, when designing a gear reducer for a manual wheelchair, it is important to calculate the torque needed to push the system uphill, taking into account the rolling resistance and the efficiency of the gear reducer. This will ensure that the gears are able to effectively reduce the force needed to climb steep hills.
  • #1
Hovda
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Hi!

I would like to apologize in advance, for my english.

I am working on a gear reducer for a manual wheelchair, and are trying to figure out what kind of design I think would work. But as I am calculating there are a few (simple) things I could need some help with.

As a test I've chosen a "wheelchair + person - system" with a total mass of 110 kg (95 for the person and 15 for chair and wheels). I am simply trying to calculate the torque needed to push this system 30 degrees uphill, and this is where I have a couple of questions:

When calculating the tourqe, is it enough just to use Tourque = RadiusOfWheel * MassOfSystem * gravity * sin(30) ? In my case this gives me T = 0.6m * 110 kg * 9.81 m/s^2 * sin(30) = 323,73 Nm. Devided by two wheels the torque would be 161,865 Nm.

I'm wondering if this is the correct way to do it? As these are wheels, do I have to take the rolling into account when calculating the tourque? All the books I have are in English, and believe it or not, it is not always easy to find the correct (relevant) information as English is not my fist language :) .

I need the tourque to be able to design gears that would do the job.

I know these questions might seem simple, but I would really appreciate if someone could give me some pointers here.

And if everything is completely off, let me know!Thank you!Mats
 
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  • #2
Hovda said:
Hi!

I would like to apologize in advance, for my english.

I am working on a gear reducer for a manual wheelchair, and are trying to figure out what kind of design I think would work. But as I am calculating there are a few (simple) things I could need some help with.

As a test I've chosen a "wheelchair + person - system" with a total mass of 110 kg (95 for the person and 15 for chair and wheels). I am simply trying to calculate the torque needed to push this system 30 degrees uphill, and this is where I have a couple of questions:

When calculating the tourqe, is it enough just to use Tourque = RadiusOfWheel * MassOfSystem * gravity * sin(30) ? In my case this gives me T = 0.6m * 110 kg * 9.81 m/s^2 * sin(30) = 323,73 Nm. Devided by two wheels the torque would be 161,865 Nm.

I'm wondering if this is the correct way to do it? As these are wheels, do I have to take the rolling into account when calculating the tourque? All the books I have are in English, and believe it or not, it is not always easy to find the correct (relevant) information as English is not my fist language :) .

I need the tourque to be able to design gears that would do the job.

I know these questions might seem simple, but I would really appreciate if someone could give me some pointers here.

And if everything is completely off, let me know!Thank you!Mats
I must say it's rather ambitious for a person to try to climb a 30-degree slope in a wheelchair without any assist.

Most of the grades I have seen specified for wheelchair access are limited to about 1:12, or say 5 degrees maximum.

Even the famously steep streets in San Francisco max out at about 17.5 degrees.

http://www.datapointed.net/2009/11/the-steeps-of-san-francisco/
 
  • #3
SteamKing said:
I must say it's rather ambitious for a person to try to climb a 30-degree slope in a wheelchair without any assist.

Most of the grades I have seen specified for wheelchair access are limited to about 1:12, or say 5 degrees maximum.

Even the famously steep streets in San Francisco max out at about 17.5 degrees.

http://www.datapointed.net/2009/11/the-steeps-of-san-francisco/
Hi!

Yes, I know 30 degrees is alot, but the number of degrees is not the point itself. It was simply a "random" number i put in. Allthough the point of the gear i am designing, is just that it should be able to reduce the "force" needed to climb so much that one could get up steep hills. But anyways, again, the degrees is not the point here :)

But thank you for pointing it out :)

Mats
 
  • #4
Hovda said:
Hi!

Yes, I know 30 degrees is alot, but the number of degrees is not the point itself. It was simply a "random" number i put in. Allthough the point of the gear i am designing, is just that it should be able to reduce the "force" needed to climb so much that one could get up steep hills. But anyways, again, the degrees is not the point here :)

But thank you for pointing it out :)

Mats
Whew! It's a good thing you didn't pull out a number like 90 degrees, or even more.

Good design should account for what is feasible versus what is not.
 
  • #5
Your torque calculation is correct.
 

Related to Calculating torque on a wheelchair

What is torque and why is it important to calculate on a wheelchair?

Torque is a measure of the force that causes an object to rotate around an axis. In the case of a wheelchair, torque is important because it determines how easily the wheelchair can be moved and how stable it is. Calculating torque allows us to understand the performance of the wheelchair and make adjustments to improve its function.

How do you calculate torque on a wheelchair?

To calculate torque on a wheelchair, you need to know the force applied to the wheel and the distance from the center of the wheel to the point where the force is applied. The formula for torque is torque = force x distance. This will give you the torque in units of Newton-meters (Nm).

What factors affect the torque on a wheelchair?

The torque on a wheelchair can be affected by several factors, including the diameter of the wheels, the type of terrain the wheelchair is being used on, the weight of the user, and the angle at which the force is being applied. These factors can impact the ease of movement and stability of the wheelchair.

How can you increase torque on a wheelchair?

There are a few ways to increase the torque on a wheelchair. One way is to increase the diameter of the wheels, which will increase the distance from the center of the wheel to the point where the force is applied. Another way is to decrease the weight of the wheelchair or the user. Additionally, choosing wheels with better traction or using gears can also increase torque.

Why is it important to consider torque when designing a wheelchair?

Considering torque when designing a wheelchair is important because it affects the overall performance and usability of the wheelchair. A wheelchair with too little torque may be difficult to maneuver, while a wheelchair with too much torque may be unstable. By understanding and calculating torque, designers can create wheelchairs that are safe, efficient, and comfortable for users.

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