Originally posted by BrianGordon
I am a design engineer by training so details and how things work very important to me. I'm more than willing to get into a discussion of linkage kinematics and dynamics complete with equations. However, in this discussion, I was using a term the term spring driven as opposed to weight driven for a type of clock and you leaped into discussion about building one and questioned whether I knew how to hob a gear. ( this is a metaphor of course). Anyway I agree that we are talking past each other and not communicating. All your details about eccentric contraction are fine in the appropriate context but just a distraction from the post in question.
The post in question's point was in swing type A the left arm is used for balance and moves moves forward and to the right start the swing which implies torque. In swing type B it is also used as a counter balance and the left hand pulls back toward the body as if one had grabbed a post and was pulling the body forward to start the swing which implies linear force. It could of course be argued that the arm motions are a reaction to a motion started elsewhere and I would certainly consider that point. F=ma and for every action there's an equal and opposite reaction, bodies at rest tend stay at rest. you know the drill.
I guess a must be a truly awful communicator to have started such a discussion about everything except the point I meant to make.
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