whirrer

So he sat and stared blankly at the screen and understanding to the bleep and whirrer of the machines, and to find some handle he might grasp on the old worlds now so finally away from him.

In Alien Hands Shatner, William 1997

It warns all other partridges near that danger is at hand, it unnerves the gunner, or it fixes the foe's attention on the whirrer, while the others sneak off in silence, or by squatting, escape notice.

Lobo, Rag and Vixen Being The Personal Histories Of Lobo, Redruff, Raggylug & Vixen Ernest Thompson Seton 1903