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How do you calculate the torque on the cam, with a force placed on the follower?

Two possibilities:

  1. Linear cam (schematic)

enter image description here

  1. Radial cam (schematic)

enter image description here

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  • $\begingroup$ You have to state the speed of the cam, esp. if could it cause follower lift off (due to inertia) as that will effect the calculation. $\endgroup$ – Paul Uszak Apr 15 '17 at 20:32
  • $\begingroup$ @PaulUszak The speed of the cam is "v", I am looking for a general solution, hence a symbolic expression. $\endgroup$ – henry Apr 16 '17 at 5:44
  • $\begingroup$ Well you could start with a simple statics vector problem using the shallowest incident angle onto the follower and assume a friction less system. Your major problem will be the friction on the cam holder in the first question. Where's the applied force in the second question? $\endgroup$ – Paul Uszak Apr 16 '17 at 12:59
  • $\begingroup$ @PaulUszak Could you explain a bit further your though on the shallowest incident angle ? Concerning your questions: The images are only schematic. I am assuming no friction, and for the second camholder, you can imagine a torsional spring attached to the follower, which acts as a counter-force.... but my goal here is not to be specific, I would like to have a general formulation (vector based, if possible). $\endgroup$ – henry Apr 16 '17 at 13:31
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Does this help?

vectors

Take the [Angle] that's most prejudicial to opposing F, and consider the lever arm to the camshaft centre. It looks like my screen grab is the worst case scenario, but with the changing lever arm to point of contact, you should really repeat this for sever angles of cam rotation. I'm sure there's software for this, but it can be done graphically by hand by plotting a surface development of the cam profile against shaft rotation, say 0 - 180 degrees. Repeat the calculation every 15 degrees and Fanny's your Aunt.

One thing. You can't possibly have a fully algebraic solution unless you have an equation for the profile of the cam as you won't be able to determine [Angle] other than by numerical /graphical means. I might be tempted to scan the cam profile and use a graphics package to segment and develop the cam profile. Or use a rule.

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