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  • Need Help Building Dog Wheelchair

    Discussion in 'The main mechanical design forum' started by toto, May 5, 2014.

    1. toto

      toto New Member

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      Hello! So about a month ago, my dog had surgery for a slipped disk, and since had regained feeling in his legs and tries to walk, but isnt strong enough to walk more than a few steps without falling over. Also the nerves that affect coordination and balance need more time to heal too. But he's an active 5 year old dog, and he needs to move! I made him a sling and some dog boots so I can hold his back end up on walks, but I think he would have more freedom with a wheelchair. It would just serve as a (hopefully) temporary tool to aid his rehabilitation. Something that will hold him up while he walks, but let him use his back legs too.
      Ive done a bit of research, and found some wheelchairs I like, and started building one out of aluminum. My biggest problem is weight. I tried the one I have out on him, and the balance is all off, which places too much weight on his shoulders. I think this relates to tire placement. Right now the bars holding him up are directly over the tires, but I want to move the tires further to the front, to maybe counter balance it a bit more. Are there any formulas or things like that I could use to get an idea of how exactly to do that? How far by what weight, etc?
      Second question: I want to put in some springs so that he actually can bend his legs and squatt a bit to pee and poop. Also that he is more or less forced to walk because with the springs, if he doesnt use his back legs, the wheelchair sags down a bit. But I want to make this adjustable as well, so that when he's tired, I can tighten something to create stiffness so that he doesnt need to put so much effort into walking.
      So this is what I have so far. I want to weld in a seat, and then pad it. Also, I think I will make the back wheels wider apart and remove the bar over the butt. If anyone has any suggestions or advice, that would be really appreciated. Thanks.

      [​IMG]
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    3. JamesOgg

      JamesOgg New Member

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      An interesting post.
      Did you bounce the idea off the do-it-yourself wheelchair of your vet? The wheelchair would put forces or torques on the spine, possibly including the location of the surgery, depending on the design. These may exceed those of natural walking.
      If the center of support in the rear was directly over the wheels, there shouldn't be a reaction force at the dog's shoulders due to the dog's weight. The load on his shoulders should be due entirely to (generally) secondary factors, such as misalignments or rolling resistance. This doesn't match the situation described, so more information is needed. Could you send a side view with the dog?
       
    4. JPfalt

      JPfalt Member

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      A few years ago my dog had surgery to repair knee joints in his hind legs and wasn't allowed to jump up or down or to go up stairs.

      I made a carrying handle which amounted to a rod and handle that went from the back hip to the shoulder. I used soft deerskin to make a sling that passed under the chest and belly of the dog and attached the sling to the rod using holes punched through the edges of the leather that looped over pins on the top of the bar. The dog became a suitcase when it was time to come up on the sofa or go up and down stairs. the sling was comfortable for the dog and provided full support over the length of his body.

      Mechanically, you want to use a sling under the dog that hangs from the frame which then goes from front shoulder to hind legs. You want the rear wheels to be just slightly ahead of the hips, so that the load on the front legs is slightly less than when the dog is in a normal stance. The sling suspends on the frame so that no torque is carried by the dog's spine.

      I would also suggest that you make the height of the rear wheels adjustable so that as the dog becomes ready to stand on it's own, you can slowly adjust up the rear wheels and progressively be able to share more weight with the rear legs. Much like slowly raising the training wheels on a bycycle.
       
    5. toto

      toto New Member

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      Thanks for replying. James, I gave the wheelchair to a friend to do some welding on a seat, so I cant take a pic now, but basically the top harness is over the front legs and held in place with a strap that goes around the dogs chest.

      JPfalt, I love the idea of a dog bag. If toto could walk I would make that, because its a pain to pick him up all the time. He's a little control freak and will just try leaping into my arms, which makes it harder to hold him because he's wiggling.
      But that idea can definitely be adapted to a wheelchair. I also like the idea of using adjustable wheels.
       
    6. toto

      toto New Member

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      Here is a picture of a wheelchair similar to what I'm trying to build. It has a welded seat. My problem is getting the balance and placement of everything right so it doesnt make the problem worse or cause more problems. I just want to give him the freedom of being able to play and run like he used to.[​IMG]
       
    7. eandres13

      eandres13 New Member

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      Hi Toto, can you give us some info about your dog? Shoulder height, breed, weight, maybe some other basic measurements? I've designed orthotics for humans and one of the big things is making sure everything is sized just right and there's not much room for things to wiggle or shift from motion.
       
    8. toto

      toto New Member

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      Hi eandres, thanks for replying. He is 10.5 kilos, 47cm long from front to back, from mid of front leg to mid of back leg 30cm. Height to back 35cm. height to stomach is 23cm. width front is 17cm and width back is about 13cm.

      He's a mixed breed. bit dachsund like.
       

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