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Looking for torque value

  1. Nov 29, 2015 #1
    Need torque for single 24in wheel vehicle weighing 150lbs to reach top speed of 25 mph in 5 sec. So far I have got wheel rev of 350 per minute but not sure of torque in Ft lbs
     
  2. jcsd
  3. Nov 29, 2015 #2

    berkeman

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    Welcome to the PF.

    What is the context of your question? Is it for schoolwork? And is the 150 pound weight a total weight including the rider? Must be a light rider on a Fixie...? :smile:
     
  4. Nov 30, 2015 #3
    Wanting to make a self propelled wheelbarrow type vehicle, wanting to figure out what size engine and hydrolic motor to power it.
     
  5. Nov 30, 2015 #4

    Mech_Engineer

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    Given a speed and time, do you know how to calculate the required acceleration? Wolfram Alpha could give you some convenient back-of-the-envelope calcs: http://www.wolframalpha.com/input/?i=24mph+in+5s

    Why are you planning to use a hydraulic motor?
     
  6. Nov 30, 2015 #5
    Want to be remote controlled. And already have electronic seloniod, for that
     
  7. Nov 30, 2015 #6

    Mech_Engineer

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    Is it a solenoid with proportional control? How will you control speed? Hydraulic drive systems also need cooling heat exchangers, will you have one of those as well?

    It seems obvious to me you should be using gas or electric motor but anyway...
     
  8. Nov 30, 2015 #7
    Yes, will have variable displacement pump, with electric control want to power it with gas engine, but need to know torque value to order hydrolic motor, and to size engine.
     
  9. Nov 30, 2015 #8

    Mech_Engineer

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    So let me ask, why not drive with the engine itself rather than adding the complexity of a hydraulic drive system?
     
  10. Dec 1, 2015 #9
    So far I have got acceleration as 7.04 ft/sec that times mass should give me torque, at 2112 ft lbs that times rpm of 300 is 633600 divided by 5252 should give me HP of 120.6? That seems high to me. I was thinking it would be closer to 12 HP... Did I do something wrong?
     
  11. Dec 1, 2015 #10
    So what I am building is a powered wheel to drive a wheelbarrow type vehicle that already has two fixed wheels in front, my power unit will mount behind and needs to have variable speed and steering up to 180 degrees and wireless remote control. I am using a variable displacement pump because I can control it with an electric actuator, and also use an electric motor to run a gear or sprocket for turning the power wheel.
     
  12. Dec 1, 2015 #11
    Using common automotive remotes give easy control to the electric motors and the hydrolic pump provides the transmission and cluch allowing me to be not have to control engine speed.
     
  13. Dec 1, 2015 #12

    Mech_Engineer

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    I would recommend you don't make its top speed nearly so fast, rear-steer reverse tricycles are nimble but will have dynamic stability issues. I'd be hesitant to take it faster than 5 mph, are you building this thing as a go-kart or wheelbarrow for hauling stuff?
     
  14. Dec 1, 2015 #13
    As a prop, will have a lightweight plastic cover that makes it appear to be a cow. I am trying to keep the weight very low to the ground to help with stability, would be interested in making it electric, but don't have much experience in that area, it will only need to operate for 3 min or less not sure of the size battery needed for that.
     
  15. Dec 1, 2015 #14
    I will try to upload some basic plans
     
  16. Dec 1, 2015 #15
    Trying to upload a drawing..
     

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  17. Dec 3, 2015 #16
    This torque is way too high. Show your work.
     
  18. Dec 3, 2015 #17
    http://www.wolframalpha.com/input/?i=24mph+in+5s

    Is where I got my acceleration from, my weight is 150 lbs

    Torque= acceleration x mass

    I am just trying to get a ball park idea of torque needed to drive wheel and HP needed in order to size motor and gears.. Can someone give me the correct values?
     
  19. Dec 3, 2015 #18
    I get about 35 ft-lbs torque at the wheel, 2.3 hp. With inefficiencies, I'd use at least a 5 hp motor.
     
  20. Dec 3, 2015 #19
    Thanks!! Insightful you are the bomb!! I was not really looking for a class on (how to) as much as the answer so I could continue my build. Thanks so much for your help!!!
     
  21. Dec 3, 2015 #20

    CWatters

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