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DaltonF.1-Visitor
1-Visitor
July 8, 2014
Solved

Top Down Design - Bearings

  • July 8, 2014
  • 1 reply
  • 3258 views

Using motion skeletons to attempt to completely animate a worm gear. All parts are already modelded top down, and the motion skeleton is complete. Problem is, I cannot figure out how to get the balls and carrier to rotate correctly (rolling along the track). The ratio of turns from the inside to the bearing carrier is a function of the diameters, and figuring out the ratio will be simple, but I'm having trouble on the actual creation of the Skeleton body. If anyone knows how to do this, or knows of a tutorial, it would be great.

Best answer by JonathanHodgson

It's essentially an epicyclic gear.

If the outer race is stationary, and the inner race is rotating (planetary epicyclic: sun in, carrier out, annulus grounded), then the ratio between the inner ring speed and the cage (carrier) speed is [R+1]:1 where R is [outer race contact dia ÷ inner race contact dia].

1 reply

T
TomD.inPDX17-Peridot
17-Peridot
July 8, 2014

The "floating balls" needs a carrier. It is similar to sun gears but you also have a linear component that needs to be programmed into the motion.

Typically people do not show the rotation of the balls but it can be done...

Radial Ball Bearing: Checking your mechanism links

    D
    DaltonF.1-VisitorAuthor
    1-Visitor
    July 9, 2014

    This seems to be what I want to do, but it only shows how to check the links to verify the balls are turning correctly against the carrier. Is there a way to to this with a motion skeleton, or will I be relegated to trying to make it work with mechanism? I don't specifically need the balls to roll, just the carrier and the balls to move. What I think would work is to setup the balls and carrier as their own assembly, then instead of assembling a bearing in, assemble the inner, outer, and carrier/ball pieces. That way (with the motion skeleton), the planes that they are assigned to will rotate independently, and therefore, the inner race and ball/carrier combo will also rotate independently.

    The question now is, what is the turn ratio for the carrier itself instead of the bearing's balls.

    J
    JonathanHodgson13-AquamarineAnswer
    13-Aquamarine
    July 9, 2014

    It's essentially an epicyclic gear.

    If the outer race is stationary, and the inner race is rotating (planetary epicyclic: sun in, carrier out, annulus grounded), then the ratio between the inner ring speed and the cage (carrier) speed is [R+1]:1 where R is [outer race contact dia ÷ inner race contact dia].

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