I've seen the pendulum is widely used as an illustration for finding a neutral, balance point between the extremes. Its movement is also periodic which shares the same characteristic with samsara. It seems that the allusions are mostly used in Taoism text, but one can see it in this site too. I think that it may be hard to find (if not possible) in the sutra, as pendulum is more well known in the West. But I've seen it and the swing used in poems influenced by Zen in my language (Vietnamese) to describe mood changing.
So is there a viewpoint of Buddhism over the pendulum? Any references, even personal opinion is fine, but it should depict the philosophy of Buddhism within in.