Abstract: A device for producing a pulsating waterjet having a manifold body with a hollow interior, a fluid inlet, and at least one outlet leading from the hollow interior and fluidly connecting the hollow interior to at least one waterjet; and a selector cam having at least one propelling vane and at least one dam that cooperates with the at least one outlet so as to sequentially align with and unalign with the at least one outlet, wherein the selector cam is rotationally mounted within the hollow interior of the manifold body, whereby fluid entering the manifold body through the fluid inlet impinges upon the at least one propelling vane imparting rotational motion to the selector cam and the at least one dam thereby rotating the at least one dam such that when the at least one dam aligns with the at least one outlet fluid is allowed to exit the manifold body through the at least one outlet and when the at least one dam unaligns with the at least one outlet fluid is thwarted from exiting the manifold body through the