Do Shopping Carts use Positive or Negative Caster?

Brakes, Steering & Suspension

  1. Dibbons

    Dibbons Well-Known Member

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    ABC Nightline has a 22 minute segment "Shopping Cart Design", but does not address the caster issue very much:
     
  2. Aeronet

    Aeronet Well-Known Member

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    When you get right down to it, it doesn't matter on a shopping cart.
     
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    • R/T Boy 67

      R/T Boy 67 Well-Known Member

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      Every one knows that positive caster has a tendency to keep the wheels straight and to return them to center after a turn. So try this. Go down to your local grocery store, find a shopping cart, and spin the front wheels around, so the wheels are sticking out front in what you call a positive caster position. Push the cart forward, and let me know what happens.
       
    • khryslerkid

      khryslerkid FBBO Gold Member FBBO Gold Member

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      This guy found a good one...
       
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      • coronet68mx

        coronet68mx FBBO Gold Member FBBO Gold Member

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        :popcorn2:
         
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        • JB400

          JB400 69 Charger FBBO Gold Member

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          • KENTON

            KENTON Well-Known Member

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            The shopping carts pivot point projected to the ground, hits it in front of the wheel where it meets the ground. Same as the motorcycle, bicycle, office chair. they all have positive caster.
             
          • KENTON

            KENTON Well-Known Member

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          • Daves69

            Daves69 Well-Known Member

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            Somehow I always get one with the "death wobble" issue!
             
          • hangn0ut

            hangn0ut Well-Known Member

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            Here's my take on this. Positive caster uses the weight of the vehicle to steer it straight. Negitive does the opposite. My 60s style altered has plenty positive caster. Straight and stable at all speeds. Hard to turn at any constant speed. Now back it up. Like after a burn out. Need to hold on tight cause those wheels will flop over and lock up in an instant. Need to move forward to unlock em. And if weight shifts forward to fast the wheels can go into a death wobble! A tap on the throttle takes care of that. So what's the point? Sometimes you need extreme examples to clarify things. And shopping carts have no effective castor. As weight over the wheels does not cause them to "steer" in any particular direction. And nose gear on aircraft generally locks straight ahead then unlocks at a very low speed. That's it. Slice away! LOL.
             
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            • hangn0ut

              hangn0ut Well-Known Member

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              Hey, don't forget that classic rear axle/suspension has its own caster and camber effects designed into it. It's in the chassis book. Check it out.
               
            • biomedtechguy

              biomedtechguy FBBO Gold Member FBBO Gold Member

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              I'm sorry. Did ya'll say something?
              :monkeyleft:
              20181205_233545.jpg :bananadance:
               
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              • Xp29h

                Xp29h FBBO Gold Member FBBO Gold Member

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                Hard to tell, depends how many times they’ve been run over in the parking lots
                 
              • coronet68mx

                coronet68mx FBBO Gold Member FBBO Gold Member

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                I wonder what our wife's woud think of us, about this deep, profound, technical spiritual, and philosophical discussion that we're having about shopping carts :bananaweed::realcrazy::steering::fool::lol:
                 
              • hangn0ut

                hangn0ut Well-Known Member

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                Yet who actually depends on em more? We laugh at em. (The carts,,,mostly.) They take em seriously, I am sure.
                 
              • WileERobby

                WileERobby FBBO Gold Member FBBO Gold Member

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                Wow, I can't believe there's actually a debate on something that's so simply obvious.
                 
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                • Mebsuta

                  Mebsuta Well-Known Member

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                  Motorcycle, bicycles - positive caster.

                  Shopping carts, dolly casters - negative caster.
                   
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                  • Cranky

                    Cranky Moderator Staff Member FBBO Gold Member

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                    Kin always tell when it's winter time around here lol
                     
                  • Photon440

                    Photon440 FBBO Gold Member FBBO Gold Member

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                    I think the castor depends on whether the cart is being pushed, or pulled backward.

                    main-qimg-638655b88171aafa5f79912ce16e6a55-c.jpg image_1.png
                     
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                    • miller

                      miller FBBO Gold Member FBBO Gold Member

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                      Aha! Finally getting scientific enough on this.
                      Now...let's get into high speed wobble...
                      :nutkick: