Abstract: A pneumatically operated and controlled pump which is capable of maintaining its efficiency and reliability in various environments. The pump head contains a spool and sleeve valve assembly operated in response to a signal pressure. The assembly controls the cycling of the pump through a pumping phase and a pump filling phase. A timing switch on the surface controls the occurrence of the signal pressure and thus the pump cycles, at preset intervals thus eliminating any lag time between the cycles and the need for operator estimations of the cycle times. This results in a virtually closed system and self contained unit.