A pump capable of dispensing both a large volume and a small volume of colorant comprises a large reciprocating positive displacement pump having a large reciprocating part, a large pump body and a large pump inlet-outlet opening, characterized in that: a small reciprocating part fixed to the large reciprocating part is disposed in the large pump body; a small pump body is disposed on a base of the large pump body, and provided with a small pump inlet-outlet opening; and the small reciprocating part, the small pump body and the small pump inlet-outlet opening constitute a small reciprocating positive displacement pump. The reciprocating positive displacement pump provided in the present invention may achieve dispensing of both a large volume and a small volume of colorant by means of a large-section pump, and thus guarantees the accuracy of the dispensed volume of colorant, and in particular, the accuracy of dispensing of a small volume of colorant; and the reciprocating positive displacement pump, when compared with the prior art, has the advantages of high accuracy and simple structure, and when compared with the structure in patent No. US2009236367A1, has the advantages of good leakproofness, high utilization of a reciprocating pump cylinder body in the length direction, and improved stroke accuracy of the reciprocating pump due to less elastic deformation of a pump support.

A pump capable of dispensing both a large volume and a small volume of colorant comprises a large reciprocating positive displacement pump having a large reciprocating part, a large pump body and a large pump inlet-outlet opening, characterized in that: a small reciprocating part fixed to the large reciprocating part is disposed in the large pump body; a small pump body is disposed on a base of the large pump body, and provided with a small pump inlet-outlet opening; and the small reciprocating part, the small pump body and the small pump inlet-outlet opening constitute a small reciprocating positive displacement pump. The reciprocating positive displacement pump provided in the present invention may achieve dispensing of both a large volume and a small volume of colorant by means of a large-section pump, and thus guarantees the accuracy of the dispensed volume of colorant, and in particular, the accuracy of dispensing of a small volume of colorant; and the reciprocating positive displacement pump, when compared with the prior art, has the advantages of high accuracy and simple structure, and when compared with the structure in patent No. US2009236367A1, has the advantages of good leakproofness, high utilization of a reciprocating pump cylinder body in the length direction, and improved stroke accuracy of the reciprocating pump due to less elastic deformation of a pump support.

A reciprocating pump, in particular a hydraulic pump of a slip-controlled vehicle braking system, includes a step piston, a differential pressure valve, and a pump outlet. The step piston includes a piston step that delimits a stepped space which is in communication with the pump outlet via the differential pressure valve. The piston step is configured such that the step space undergoes suction and displacement in a direction opposite to a displacement space, and in smaller quantities than suction and displacement in the displacement space, such that brake fluid volume flow in the pump outlet is evened out, and such that pressure pulsations are inhibited.

In certain examples, a printing system comprises: a depositing system to deposit printing fluid on a print medium; a reservoir; and a displacement pump to move printing fluid to the depositing system from the reservoir. The displacement pump comprises: a pump body defining a chamber, an inlet to fluidly connect the chamber to the reservoir, and an outlet to fluidly connect the chamber to the depositing system; and a displacement member movable relative to the pump body; the displacement member having an outer surface and comprising a cavity located in a portion of the outer surface disposed in the chamber. In use, the displacement member is movable to close the inlet and to force printing fluid in the chamber through the outlet to the depositing system.

In certain examples, a printing system comprises: a depositing system to deposit printing fluid on a print medium; a reservoir; and a displacement pump to move printing fluid to the depositing system from the reservoir. The displacement pump comprises: a pump body defining a chamber, an inlet to fluidly connect the chamber to the reservoir, and an outlet to fluidly connect the chamber to the depositing system; and a displacement member movable relative to the pump body; the displacement member having an outer surface and comprising a cavity located in a portion of the outer surface disposed in the chamber. In use, the displacement member is movable to close the inlet and to force printing fluid in the chamber through the outlet to the depositing system.

An intensifier pump includes a piston including at least two selectable piston diameters. Additionally, the intensifier pump includes a plunger that in operation interacts with the piston. The plunger includes a plunger diameter that is smaller than each of the at least two selectable piston diameters.

An intensifier pump includes a piston including at least two selectable piston diameters. Additionally, the intensifier pump includes a plunger that in operation interacts with the piston. The plunger includes a plunger diameter that is smaller than each of the at least two selectable piston diameters.

A drive unit for a diaphragm pump may be provided, wherein the drive unit comprises a hollow body and a piston which is arranged so as to be movable in the first hollow body along an axis of the hollow body, wherein the piston divides the hollow body into a first chamber, which is connectable to the diaphragm pump, and a second chamber, which is coupleable to a gas reservoir. The second chamber comprises an inlet valve and an outlet valve, such that a gas flow is drawn into the chamber via the inlet valve and is forced out of the chamber via the outlet valve.

Double acting positive displacement fluid pump Double acting positive displacement fluid pump having two or more housings (3A,20A), a first housing (3A) comprising a pump fluid inlet chamber (3) and a separate housing (20A) comprising a pump fluid outlet chamber (20), the pump fluid inlet chamber (3) being in fluid communication with the pump fluid outlet chamber (20) by means of a through passage (6A), said through passage (6A) having an inlet positioned within the pump fluid inlet chamber (3) and an outlet positioned within the pump fluid outlet chamber (20), the inlet portion (6) of the plunger having an effective displacement area which is larger than the effective displacement area of the outlet portion (21) of the plunger, said passage being further provided with a combined suction-discharge valve assembly (9) arranged in the through passage, wherein the pump fluid inlet chamber (3) comprises a central pump fluid inlet chamber axis and a fluid entry (1B) having an inlet suction valve assembly (2), the pump fluid outlet chamber (20) comprises a central pump fluid outlet chamber axis and the through passage comprises a through passage axis, wherein the central pump fluid inlet chamber axis, the central pump fluid outlet chamber axis and the through passage axis are coaxial and form a central double acting positive displacement fluid pump axis.

Double acting positive displacement fluid pump Double acting positive displacement fluid pump having two or more housings (3A,20A), a first housing (3A) comprising a pump fluid inlet chamber (3) and a separate housing (20A) comprising a pump fluid outlet chamber (20), the pump fluid inlet chamber (3) being in fluid communication with the pump fluid outlet chamber (20) by means of a through passage (6A), said through passage (6A) having an inlet positioned within the pump fluid inlet chamber (3) and an outlet positioned within the pump fluid outlet chamber (20), the inlet portion (6) of the plunger having an effective displacement area which is larger than the effective displacement area of the outlet portion (21) of the plunger, said passage being further provided with a combined suction-discharge valve assembly (9) arranged in the through passage, wherein the pump fluid inlet chamber (3) comprises a central pump fluid inlet chamber axis and a fluid entry (1B) having an inlet suction valve assembly (2), the pump fluid outlet chamber (20) comprises a central pump fluid outlet chamber axis and the through passage comprises a through passage axis, wherein the central pump fluid inlet chamber axis, the central pump fluid outlet chamber axis and the through passage axis are coaxial and form a central double acting positive displacement fluid pump axis.