I really tried to look up information about this on the internet, but there's very few info available, and the info that is there is incomplete. I saw this diagram but still don't understand how the switch work.

It seem simple to have a trolley pole follow the wire, it is simply U shaped and a spring pulls it up, so that force is applied against the wire. However I cannot possibly imagine how does the switches function, mechanically speaking. Also how they prevent short-circuit at switches' frog where both poles touches eachother.

Also, back when tramways also had a trolley pole, did it have switches using the same mechanics as in a trolleybus switch ?