A pneumatic oscillator for providing pumping force to a pump. The oscillator has a single valve for controlling both the rate of oscillation of the oscillator and the flow of air. The valve includes a shuttle member and a detent mechanism. The detent mechanism controls the air flow in the oscillator and to the pump to which the oscillator is attached and the detent mechanism for regulating oscillation of the shuttle member. The configuration of the shuttle member and the detent mechanism eliminates the need for an additional valve to regulate oscillation of the oscillator. A cycle controller corresponding with the detent mechanism is adapted to change the rate of oscillation of shuttle member such that the need for additional valves or controllers for regulating the rate of oscillation is obviated.