Abstract: A fluid pressure operated actuator, for example for controlling operation of a pneumatically driven metering pump for liquids. In a specific embodiment, the actuator is a rotary actuator and includes a piston/cylinder unit coupled at one end to a rack and pinion drive for reciprocating a rotary control valve of the pump, and at its opposite end to a valve which controls the air supply to the main liquid delivery plunger of the pump. The coupling to the air supply valve is designed to allow limited lost motion at each end of the stroke of the piston so as to ensure that the rotary valve is turned before the plunger of the pump begins to move.

Abstract: A metering pump is disclosed and includes a unitary pumping assembly secured to a base so as to be removable from the base as a unit e.g. for cleaning. The pump is of the plunger type and includes at least one plunger mounted to reciprocate in a pump cylinder, and a rotary valve for controlling flow of liquid into and out of the cylinder under the effect of reciprocation of the plunger. A linear actuator and a rotary actuator are each permanently mounted on the base for actuating respectively the plunger and the rotary valve. The linear actuator can be coupled to the plunger by disengageable coupling means including interfitting but physically unconnected male and female formations. The rotary actuator is similarly disengageably coupled to the valve member by a key and slot coupling. The disengageable coupling means allow the pumping assembly to be removed as a unit from the base by simply releasing a securing screw or the like.