The sprinkler head pivots on a bearing on top of its threaded attachment nut. The head is driven in a circular motion by the force of the outgoing water and at least one arm extends from the head. The sprinkler arm is repeatedly pushed back into the water stream by a spring.
An impact sprinkler is a type of irrigation sprinkler in which the sprinkler head, driven in a circular motion by the force of the outgoing water, pivots on a bearing on top of its threaded attachment nut.