Torque-Required::Stair-Climbing Device

  1. I am trying to figure out how to design a stair-climbing device similar to a hand-cart that climbs stairs.

    I know that the loading will be ~500 lb.

    It uses a 3-wheel climbing design design like this except motorized.

    I am trying to figure out how much torque I will need at the output of the gear box. I am assuming that this is simply a function of the distance from the climbing-wheel to the loading.

    I also would like to figure out what size motor would work in that it should be relatively small and run off of a reasonably small portable power source.

    I have no real design experience, so I was hoping for some input/advice.

    What kind of small portable motors are out there and where can I see their specs?

    What kind of power sources are out there?

    If my questions are not that clear, let me know and I will try to elaborate.


    EDIT to help put this into better perspective, the motor is to power a 3-wheeled design like the one shown above, but it is to be used on an Ambulance Gurney (stretcher) to assist in moving 'larger' people up and down stairs.
    Last edited: Jun 14, 2009
  2. jcsd
  3. Anyone know of any good sites for motors of this sort? Google is ok, but I would like some recommended sites.

    Searching "motors" is a little painstaking.

    EDIT: Ok, I am here right now.

    Can someone explain what armature vs field voltage? Do I need to consider these?

    I googled around and found that armature voltage is the occurs on the coils, but I am not sure why I need to know this :redface:
    Last edited: Jun 13, 2009
  4. Any thoughts on motors/power sources? I am looking at something like THIS, but I am not sure if there is a lightweight portable rechargeable power source to go with.

    I figured that the torque I need to deliver is ~4000 lb-in

    Can I go with a smaller motor without getting to crazy with the gear box? Is 2 HP at 2500 rpm considered a "big" motor.

    I know this is a broad question that is design particular, but I am in need of some help/advice as a strarting point/

  5. Mech_Engineer

    Mech_Engineer 2,299
    Science Advisor
    Gold Member

    You'll be able to find a motor that fits your specifications on

    As for size of the motor and how much power will be required, I would look into how high you're looking to lift the patient/gurney. By doing this, you can calculate the required potential energy change which can give you an idea on battery sizing.

    Also I have to ask- why the heck would you want to carry a patient up stairs on a gurney? What about elevators?
    Last edited: Jun 15, 2009
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