8 Replies Latest reply on Jan 23, 2015 9:01 AM by Bill McEachern

    Gear Contact Forces

    Evan Boso
    Evan Boso Jan 21, 2015 2:52 PM

      Am I able to plot of contact forces between gears only using the gear mate? I'm fairly new to solidworks and would prefer avoiding setting up a "teethed" gear. If you need more information to answer just let me know! Thanks

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        • Re: Gear Contact Forces
          Bill McEachern
          Bill McEachern Jan 21, 2015 7:15 PM (in response to Evan Boso)

          You can get torque from motion for disc like geometries for gears. Pick you moment arm for force if you like then.

          • Re: Gear Contact Forces
            Mike Pogue
            Mike Pogue Jan 22, 2015 11:51 AM (in response to Evan Boso)

            Gear forces are very easy to calculate without sophisticated software. Gear stresses are a little more involved, but they are still well understood. Post a schematic of you gear train and I'll tell you the forces.

              • Re: Gear Contact Forces
                Evan Boso
                Evan Boso Jan 22, 2015 1:58 PM (in response to Mike Pogue)

                Within the setup I have a two gears with a pre-compressed spring attached to fixed points of each gear. Rotation of the of this system would generally be dictated by a displacement of a rack but I just set specific rotation for one of the gears to run through in motion analysis. Since the pre-comressed spring extends over this period the force drops but due to where they are attached to the gear the moment arm increases. My goal is to determine the force the top gear would apply to the rack or simply the torque the spring creates on each gear.

                *the spring remains in compression throughout the motion

                 

                I know I might have not done the best job describing that but I've attached two images and hopefully it will make sense.

                 

                I would have attached the file but I’m not entirely sure how.

                Thanks!

                 

                forum1.png

                forum2.png

                  • Re: Gear Contact Forces
                    Mike Pogue
                    Mike Pogue Jan 22, 2015 4:03 PM (in response to Evan Boso)

                    Assuming,

                     

                    Both gears are free to rotate around their axes.

                    The rack can only slide back and forth.

                     

                    I can get the answer as force on the rack as a function of displacement. Give me a minute.

                    • Re: Gear Contact Forces
                      Mike Pogue
                      Mike Pogue Jan 23, 2015 9:20 AM (in response to Evan Boso)

                      This is more complicated than some standard torque in/out gear train. So, maybe not a silly use of sophisticated software like a claimed. Still, I said I could solve it, so here is the solution. You might want to leave this question up until a motion expert posts the solution you are looking for.

                       

                      I made up the parameters--you will need to supply them to get your answer. Cool problem.

                       

                      Edit: Fixed a couple of problems.

                      • Re: Gear Contact Forces
                        Bill McEachern
                        Bill McEachern Jan 23, 2015 9:01 AM (in response to Evan Boso)

                        Hi Even,

                        Motion is a rigid body mechanics program - depending on how you set up the supports for the gears and how they interact the spring won't do a thing in terms of transmitting force depending on how the rotational degree of freedom is handle - like say a revolute joint - its infinitely stiff. To set this up so that the gear "floats" requires using bushings If you want some stiffness) or releasing the appropriate degree of freedom. Then the spring can actually transmit forces to the other entities.