I remember a contraption that looked a little like this from my childhood:
Our neighbors had one. Me and my brother would go over and the neighbors would get on it and we would have a blast. You would push the pedals out and pull the handles in, and do the opposite to start spinning round and round. The harder and faster we did this the faster it would spin. We told ourselves that if we went fast enough we could become airborne like a helicopter. We never took off, but it was sure fun trying.
I remember playing in the sprinklers and then lying down on the warm pavement, and then we'd get up to see the patterns our wet bodies made.
We also rode bikes and put cards in the spokes using clothes pins that would make flapping sounds as we rode.
And I remember the lazy summer music that we would just listen to while we relaxed after a hard day of play.