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Is this possible? Omnidirectional Load Pin

  1. Nov 17, 2014 #1
    Please take a look at the attached diagram. This is a rough representation of a concept my team and I would like to implement in a project. Initial research suggests that such pin-based weighing systems are strictly unidirectional (i.e the basic clevis pin loan cells). Our platform rotates while bearing a load with force always in direction of gravity i.e. load does not rotate with weighing cylinder, but "hangs" (forgive my verbiage here - I'm not an engineer). Hopefully the diagram conveys the idea. Assuming I've provided enough information, is this possible either utilizing currently available hardware or designing a new load sensor with multiple strategically placed strain gauges?

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  2. jcsd
  3. Nov 17, 2014 #2

    Simon Bridge

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    Welcome to PF;
    What is the problem this device is supposed to overcome - and what is it supposed to do?

    It is usually not desirable to allow the load pin to rotate, but it is not forbidden.
    An unthreaded clevis pin passing right through the clevis and held by a split pin, or even a regular bolt, will do this.
  4. Nov 18, 2014 #3


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    More importantly, what's our cut of the royalties? :p
  5. Nov 19, 2014 #4
    The entire shaft spins as part of a larger mechanical assembly. Without going into unnecessary detail, we need it to measure the weight of a variable load that will hang beneath. The direction of force is always down, but variable by 360* in relation to the "clevis pin load cell" like shaft as it spins (b) . Shear force occurs between a and b, this would be where the strain gauges would be (think 1/2 of a clevis pin load cell) Don't know if that clears it up any..

    Rotation "not forbidden" - interesting...why is it undesirable? Does it affect accuracy? Are we talking 360* rotation? Can you link to any technical material that might explain in more detail how the strain gauges are set up in a clevis pin load sensor so that a weight reading could be obtained despite pin rotation?

    Thanks immensely!
  6. Nov 19, 2014 #5

    Simon Bridge

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    You were talking about a load pin and referred to a clevis pin - desirability really depends on function: think "hinges".
    The device you have drawn could be configured to measure weight - but there are better ways. You need the load supports to slip but there should be enough friction to get a different tension on each side of the shaft ... unless you intend that the load should turn with the shaft.
    Weight always points down - that is the definition of "down" - even if the load is in vertical circular motion.
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