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How to attach wheel to axel? and how to choose motor

  1. Apr 7, 2017 #1
    I need to know how to attach a wheel to an axel, but first of all, i need an axel with a gear pre-built into it. The axel needs to be over 20 inches long (because that is the width of my vehicle) and support bicycle/tricycle wheels.

    Does anyone know of such wheels and axels? (The wheels have to be thin).
    My second problem is choosing a motor for my vehicle.

    The motor will be pneumatic and run off of a tank with a capacity of probably a little over 7127 inches cubed at ~100-110 psi.
    I want to get a motor from here: http://psiautomation.com/model_specs.cfm?horsepower=0.75&model=DVA-003
    But my main concern is the air consumption rating of 45 scfm. And my big question is how something that takes in 90psi can generate 3/4 horsepower. How does that happen?

    Finally, if i cant supply enough air to the motor using a tank, could probably just put an electric generator in with the air inflator to make it move.
  2. jcsd
  3. Apr 7, 2017 #2


    Staff: Mentor

    An axle (not axel, which is a move in ice skating) is a shaft that can be either fixed or can rotate with the wheel. Since the drive gear will be attached to the axle, the axle will need to rotate.
    You could attach a hub to the axle and bolt the wheel to the hub. The hub could be permanently attached (welded) or the end of the axle could be splined, matching internal splines in the hub, or the end of the axle could have a groove that matches a groove inside the hub. A Woodruff key would hold the hub and wheel in place. If your vehicle only needs to move in a straight line, it's OK to have both rear wheels rigidly attached to the axle. If the vehicle needs to be able to turn, you could let the non-drive wheel rotate freely on the axle.

    On bicycles and many motorcycles, the drive gear is firmly attached to the rear wheel, and the axle does not revolve.
  4. Apr 7, 2017 #3


    User Avatar

    Staff: Mentor

    Mechanical storage of energy is not very volume efficient or weight efficient. Chemical storage (in gasoline or a battery) is more efficient. Why are you wanting to make this vehicle run on pneumatic power?
  5. Apr 7, 2017 #4
    First, and most important, where are you getting this tank? 110 psi is a lot of pressure and can be quite deadly if the tank is not designed for such pressure.

    Your 7127 cu inch tank holds about 4 cubic feet. If the pressure is 110 psig, the tank holds about 4 * 110/14.7= 31 scf. So the best you're going to do is operate for about 31/45 = 0.7 minutes or 40 seconds. And that doesn't account for the tank pressure dropping as the contents are depleted -- after all, the air motor needs some pressure to run (you need to get that number from the motor specs). It sounds like you have more thinking to do on this plan.
  6. Apr 8, 2017 #5
    My plans already have changed. I planned on using 3" schedual 40 pvc pipe for the tank.
    My vehicle will probably be using electricity from now on.
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