Abstract: A direct action fluid motor and injection pump is disclosed which injects small quantities of a second fluid into a primary fluid stream. A housing has an inlet and an outlet connected to a primary fluid conduit. The housing contains a stepped piston which reciprocates in response to the fluid pressure applied alternately to the closed small and large face of the piston. A valve set alternately closes one and opens the other of the faces. A valve positioner carried with the piston is held in alternate stable positions by cooperating springs on the valve positioner and a post in the piston. Stop members are located above and below the piston travel, each associated with an actuating spring. The valve positioner is preshifted at the end of the stroke, using the full force of the piston, by stop members to move the valve positioner and valve set to an intermediate unstable position.

Abstract: A magnetically actuated fluid motor has a shiftable member having valve members for alternately closing one and opening the other of large and smaller faces of a stepped piston reciprocating in a housing. The shiftable member carries a magnet and is shiftable to collocate the magnet with one of spaced apart magnet attractors. A magnetic holding force between the magnet and attractors exceeds a simultaneous resilient counterforce supplied by spring members operating on the shiftable member. When the magnetic holding force is weakened by application of a separating force to separate the magnet from an attractor, stored energy in the compressed springs is released to shift the shiftable member. Separating force is applied through stops which arrest the shiftable member while the piston continues to move, without immediately opening the closed face of the stepped piston.

Abstract: An additive injection pump has a rolling diaphragm mounted between a reciprocable assembly and a cylinder to create a secondary fluid pumping chamber in the lower end of the cylinder. The reciprocable assembly has an internal one-way flow passage between the pumping chamber and an opposite end portion of the assembly having an outlet. The selective positioning of a valve member at the bottom of the reciprocable assembly establishes a predetermined quantity of secondary fluid supplied through an inlet at the bottom of the cylinder. When the cylinder is attached to a housing having a primary fluid stream and the assembly is reciprocated by a fluid motor in the housing, secondary fluid in predetermined doses is injected into the primary fluid stream.

Abstract: A reciprocating primary fluid driven motor has a stepped piston in a housing having a center hanging actuator rod which extends into the piston to periodically cooperate with an axially shiftable connector member in the piston which operates valves which establish the reciprocating stroke of the piston by opening and closing valve members on the larger and smaller faces of the stepped piston. A block member with compression spring drivers pivotally mounted inside the piston slides on the actuator rod during movement of the piston. The drivers are compressed in response to spaced stops on the actuator rod during continued movement of the piston until a sudden over-center movement of the block member shifts the connector to operate the valve members to cause reciprocation of the piston. Quiet operation during shifting is provided by shock absorbers. No sliding seal with the actuator rod is necessary. Provision for bleeding air from the housing chamber facilitates startup.