Piston type pump

Claim 2

A piston type pump comprising: a. a crankcase drive housing portion having a pair of opposed flat surfaces, a cylindrical bore extending through said drive housing portion and communicating with the medial open portion of said drive housing, said medial open portion constituting a lateral drive receiving enlargEment disposed at an intermediate portion of said bore, at least two laterally disposed passageways each extending through said opposed flat surfaces disposed on opposite sides of said cylindrical bore, an inlet port communicating with one of said passageways and an outlet port communicating with the other of said passageways, each of said passageways having a certain predetermined diameter at said opposed flat surfaces; b. at least two cylinder block housings each having inner and outer opposed flat surfaces secured to said drive housing along opposed surfaces of said drive housing, each of said cylinder block housings having a cylindrical extension bore disposed coaxially with the cylindrical bore formed in said drive housing and with a diameter at least equal to the diameter of said cylindrical bore, a piston received in each of said cylindrical extension bores, a reciprocating drive means coupled to each of said pistons, a pair of substantially laterally disposed extension passageways extending through each of said cylinder block housings, each extension passageway having a drive housing abutting portion disposed in continuation with and communicating with one of the laterally disposed passageways of said drive housing, an inlet valve assembly inserted in one of said extension passageways within each cylinder block housing, and an outlet valve assembly inserted in the other of said extension passageways within each cylinder block housing; c. a housing head secured over the cylinder bore and each of said laterally disposed extension passageways along the outer flat surface of the cylinder block housing, each housing head having a flat forward area along and adjacent portions of the periphery thereof and a rearwardly recessed area inscribed within said flat forward area and providing communication between said pair of passageways and said cylindrical bore; and d. each laterally disposed extension passageway having a counter-bore portion with shoulders abutting said inlet and outlet valve assemblies at marginal portions thereof whereby said counter-bore shoulders and one cylinder block contacting surface selected from said opposed flat surface and said flat forward area cooperate to hold the valve assemblies in their inserted positions within said cylinder block housing without additional fastening means.

Claim 3

The structure set forth in claim 1 wherein each of said valve assemblies includes a resilient ring extending about its periphery for effecting a seal with its particular passageway.

Claim 4

The structure set forth in claim 1 in which said valve assemblies are each constructed of two outer parts interfitted to provide a unit, one of said parts having a valve seat, and said unit further including a spring biased poppet engageable with said seat.

Claim 5

The structure as set forth in claim 1 being particularly characterized in that said drive means comprises a drive shaft journaled for rotation within said housing, an eccentric crank pin projecting from the end of said shaft, roller means on said crank pin, a cross-head yoke member having an inner surface circumscribing said roller and having connecting rods removably coupling said cross-head yoke member to each of said pistons, the outer surface of said roller and the inner surface of said cross-head yoke member having substantially matching arcuately formed contours, the contours being convex and concave respectively in axial cross section.

Claim 6

The structure of claim 1 being particularly characterized in that seal means are provided along the mating opposed surfaces between said drive block and said cylinder block about the periphery of each of said laterally disposed passageways.

Claim 7

The structure as set forth in claim 1 being particularly characterized in that guide means are provided within said drive housing portion for guiding the reciprocatory action of said pistons.

Claim 8

A piston type pump comprising: a. a housing defining a closed loop and having an endless passageway formed therein, said Closed loop surrounding an inner crankcase cavity, an inlet communicating with said endless passageway, an outlet spaced from said inlet and also communicating with said endless passageway, a pair of open-end cylinders lying mutually in spaced relation between said inlet and said outlet, each communicating with said endless passageway and with said inner open space, said cylinders being substantially diametrically opposed, a piston reciprocably positioned in each of said cylinders; and b. a drive shaft journaled for rotation within said housing, an eccentric crank portion along said shaft, self-aligning drive bearing means on said crank portion, a cross-head having an inner surface circumscribing a substantial portion of the periphery of said self-aligning drive bearing means with an open segment along one surface thereof to receive said drive bearing means and having connecting rods coupling said cross-head to each of said pistons, the outer surface of said self-aligning drive bearing means and the portions of the inner surface of said cross-head directed generally toward said cylinders having substantially matching arcuately formed contours, the said contours being convex and concave respectively in axial cross section, and a recessed zone formed along the closed yoke portion of said inner surface for receiving said drive bearing means while at an angular disposition shifted an arcuate distance of 90* from its normal position.

Claim 9

A piston type pump comprising: a. a housing defining a closed loop and having an endless passageway formed therein, said Closed loop surrounding an inner crankcase cavity, an inlet communicating with said endless passageway, an outlet spaced from said inlet and also communicating with said endless passageway, a pair of open-end cylinders lying mutually in spaced relation between said inlet and said outlet, each communicating with said endless passageway and with said inner open space, said cylinders being substantially diametrically opposed, a piston reciprocably positioned in each of said cylinders; and b. a drive shaft journaled for rotation within said housing, an eccentric crank portion along said shaft, self-aligning drive bearing means on said crank portion, a cross-head having an inner surface circumscribing a substantial portion of the periphery of said self-aligning drive bearing means with an open segment along one surface thereof to receive said drive bearing means and having connecting rods coupling said cross-head to each of said pistons, the outer surface of said self-aligning drive bearing means and the portions of the inner surface of said cross-head directed generally toward said cylinders having substantially matching arcuately formed contours, the said contours being convex and concave respectively in axial cross section, and a recessed zone formed along the closed yoke portion of said inner surface for receiving said drive bearing means while at an angular disposition shifted an arcuate distance of 90* from its normal position.

Claim 10

The piston type pump as defined in claim 1 being particularly characterized in that each of said pistons is coupled to said reciprocating drive means by a cam follower means, a centrally disposed drive yoke coupling said cam follower means, one to another, and a central shaft disposed coaxially with said pistons and cam follower means for threadably coupling each of said pistons to its associated cam follower means.

Claim 11

A piston type pump comprising: a. a housing defining a closed loop and having an endless passageway formed therein, said closed loop surrounding an inner crankcase cavity, an inlet communicating with said endless passageway, an outlet spaced from said inlet and also communicating with said endless passageway, a pair of open-end cylinders lying mutually in spaced relation between said inlet and said outlet, each communicating with said endless passageway and with said inner open space, said cylinders being substantially diametrically opposed, a piston reciprocably positioned in each of said cylinders; b. a drive shaft journaled for rotation within said housing, an eccentric crank portion along said shaft; and c. means including resilient seal means and relatively rigid guide means disposed within said cylinders to contact the surface of said pistons for isolating said pistons within each of said cylinders, said means further including spacers between said seal means and said guide means, the axial length of said spacers being in excess of the length of the reciprocable stroke provided said pistons by said eccentric crank portion.

Claim 12

A piston type pump comprising: a. a housing defining a closed loop and having an endless passageway formed therein, said closed loop surrounding an inner crankcase cavity, an inlet communicating with said endless passageway, an outlet spaced from said inlet and also communicating with said endless passageway, a pair of open-end cylinders lying mutually in spaced relation between said inlet and said outlet, each communicating with said endless passageway and with said inner open space, said cylinders being substantially diametrically opposed, a piston reciprocably positioned in each of said cylinders; b. a drive shaft journaled for rotation within said housing, an eccentric crank portion along said shaft; and c. means including resilient seal means and relatively rigid guide means disposed within said cylinders to contact the surface of said pistons for isolating said pistons within each of said cylinders, said means further including spacers between said seal means and said guide means, the axial length of said spacers being in excess of the length of the reciprocable stroke provided said pistons by said eccentric crank portion.

Claim 13

A piston type pump comprising: a. a housing defining a closed loop and having an endless passageway formed therein, said closed loop surrounding an inner crankcase cavity, an inlet communicating with said endless passageway, an outlet spaced from said inlet and also communicating with said endless passageway, a pair of open-end cylinders lying mutually in spaced relation between said inlet and said outlet, each communicating with said endless passageway and with said inner open space, said cylinders being substantially diametrically opposed, a piston reciprocably positioned in each of said cylinders; b. a drive shaft journaled for rotation within said housing and terminating in an eccentric drive cam means with a drive surface, cam follower means having means coupling to each of said pistons, and a coupling yoke with an axis generally transverse to the axis of said drive shaft and having an inner surface disposed adjacent said drive cam and an outer surface, thE yoke being arranged generally axially outwardly of said drive shaft and being coupled to each of said cam follower means; low friction abutment ring means having a central ring axis which is generally parallel to the axis of said drive shaft arranged immediately adjacent the outer surface of said yoke for controlling the axial disposition of said yoke during reciprocation thereof, said low friction abutment ring means having an annular abutment surface arranged generally parallel to the axis of said coupling yoke, said abutment surface being generally commensurate with the pattern generated by the drive surface of the eccentric drive cam means.

Claim 14

A piston type pump comprising: a. a housing defining a closed loop and having an endless passageway formed therein, said closed loop surrounding an inner crankcase cavity, an inlet communicating with said endless passageway, an outlet spaced from said inlet and also communicating with said endless passageway, a pair of open-end cylinders lying mutually in spaced relation between said inlet and said outlet, each communicating with said endless passageway and with said inner open space, said cylinders being substantially diametrically opposed, a piston reciprocably positioned in each of said cylinders; b. a drive shaft journaled for rotation within said housing and terminating in an eccentric drive cam means with a drive surface, cam follower means having means coupling to each of said pistons, and a coupling yoke with an axis generally transverse to the axis of said drive shaft and having an inner surface disposed adjacent said drive cam and an outer surface, thE yoke being arranged generally axially outwardly of said drive shaft and being coupled to each of said cam follower means; low friction abutment ring means having a central ring axis which is generally parallel to the axis of said drive shaft arranged immediately adjacent the outer surface of said yoke for controlling the axial disposition of said yoke during reciprocation thereof, said low friction abutment ring means having an annular abutment surface arranged generally parallel to the axis of said coupling yoke, said abutment surface being generally commensurate with the pattern generated by the drive surface of the eccentric drive cam means.

Claim 15

The piston type pump as defined in claim 10 being particularly characterized in that said low friction abutment ring means is fabricated from a composition selected from the group consisting of nylon and molded polytetrafluorethylene.

Claim 16

A piston type pump comprising: a. a crankcase drive housing portion having a pair of opposed flat surfaces, a cylindrical bore extending through said drive housing portion and communicating with the medial open portion of said drive housing, said medial open portion constituting a lateral drive receiving enlargement disposed at an intermediate portion of said bore, at least two laterally disposed passageways each extending through said opposed flat surfaces disposed on opposite sides of said cylindrical bore, an inlet port communicating with one of said passageways and an outlet port communicating with the other of said passageways, each of said passageways having a certain predetermined diameter at said opposed flat surfaces; b. at least two cylinder block housings each having inner and outer opposed flat surfaces secured to said drive housing along the opposed surfaces of said drive housing, each of said cylinder block housings having a cylindrical extension bore disposed coaxially with the cylindrical bore formed in said drive housing with a diameter at least equal to the diameter of said cylindrical bore, a piston received in each of said cylindrical extension bores, reciprocating drive means coupled to each of said pistons, a pair of substantially laterally disposed extension passageways extending through each of said cylinder block housings, each extension passageway having a drive housing abutting portion disposed in continuation with and communicating with one of the laterally disposed passageways of said drive housing, an inlet valve assembly inserted in one of said extension passageways within each cylinder block housing, and an outlet valve assembly inserted in the other of said extension passageways within each cylinder block housing; c. a housing head secured over the cylinder bore and each of said laterally disposed extension passageways along the outer flat surface of the cylinder block housing, each housing head having a flat forward area along and adjacent portions of the periphery thereof and a rearwardly recessed area inscribed within said flat forward area and providing communication between said pair of passageways and said cylindrical bore; d. each laterally disposed extension passageway having a portion abutting said inlet and outlet valve assemblies at marginal portions thereof whereby to hold the valve assemblies in their inserted positions within said cylinder block housing without additional fastening means; and e. said drive means comprising a drive shaft journaled for rotation within said housing, an eccentric crank pin projecting from the end of said shaft, roller means on said crank pin, a cross-head yoke member having an inner surface circumscribing said roller and having connecting rods removably coupling said cross-head yoke member to each of said pistons, the outer surface of said roller and the inner surface of said cross-head yoke member having substantially matching arcuately formed contours, the contours being convex and concave respectively in axial cross section, each arcuately formed contour having a substantially common oRigin disposed along the axis of said crank pin and a recessed zone formed along the closed axially extending face of said yoke member for receiving said roller means within said yoke with said roller means disposed at an arcuate distance of 90* from its normal driving position.

Claim 17

A piston type pump comprising: a. a crankcase drive housing portion having a pair of opposed flat surfaces, a cylindrical bore extending through said drive housing portion and communicating with the medial open portion of said drive housing, said medial open portion constituting a lateral drive receiving enlargement disposed at an intermediate portion of said bore, at least two laterally disposed passageways each extending through said opposed flat surfaces disposed on opposite sides of said cylindrical bore, an inlet port communicating with one of said passageways and an outlet port communicating with the other of said passageways, each of said passageways having a certain predetermined diameter at said opposed flat surfaces; b. at least two cylinder block housings each having inner and outer opposed flat surfaces secured to said drive housing along the opposed surfaces of said drive housing, each of said cylinder block housings having a cylindrical extension bore disposed coaxially with the cylindrical bore formed in said drive housing with a diameter at least equal to the diameter of said cylindrical bore, a piston received in each of said cylindrical extension bores, reciprocating drive means coupled to each of said pistons, a pair of substantially laterally disposed extension passageways extending through each of said cylinder block housings, each extension passageway having a drive housing abutting portion disposed in continuation with and communicating with one of the laterally disposed passageways of said drive housing, an inlet valve assembly inserted in one of said extension passageways within each cylinder block housing, and an outlet valve assembly inserted in the other of said extension passageways within each cylinder block housing; c. a housing head secured over the cylinder bore and each of said laterally disposed extension passageways along the outer flat surface of the cylinder block housing, each housing head having a flat forward area along and adjacent portions of the periphery thereof and a rearwardly recessed area inscribed within said flat forward area and providing communication between said pair of passageways and said cylindrical bore; d. each laterally disposed extension passageway having a portion abutting said inlet and outlet valve assemblies at marginal portions thereof whereby to hold the valve assemblies in their inserted positions within said cylinder block housing without additional fastening means; and e. said drive means comprising a drive shaft journaled for rotation within said housing, an eccentric crank pin projecting from the end of said shaft, roller means on said crank pin, a cross-head yoke member having an inner surface circumscribing said roller and having connecting rods removably coupling said cross-head yoke member to each of said pistons, the outer surface of said roller and the inner surface of said cross-head yoke member having substantially matching arcuately formed contours, the contours being convex and concave respectively in axial cross section, each arcuately formed contour having a substantially common oRigin disposed along the axis of said crank pin and a recessed zone formed along the closed axially extending face of said yoke member for receiving said roller means within said yoke with said roller means disposed at an arcuate distance of 90* from its normal driving position.

Claim 18

A piston type pump comprising: a. a crankcase drive housing portion having a pair of opposed flat surfaces, a cylindrical bore extending through said drive housing portion and communicating with the medial open portion of said drive housing, said medial open portion constituting a lateral drive receiving enlargement disposed at an intermediate portion of said bore, at least two laterally disposed passageways each extending through said opposed flat surfaces disposed on opposite sides of said cylindrical bore, an inlet port communicating with one of said passageways and an outlet port communicating with the other of said passageways, each of said passageways having a certain predetermined diameter at said opposed flat surfaces; b. at least two cylinder block housings each having inner and outer opposed flat surfaces secured to said drive housing along the opposed surfaces of said drive housing, each of said cylinder block housings having a cylindrical extension bore disposed coaxially with the cylindrical bore formed in said drive housing with a diameter at least equal to the diameter of said cylindrical bore, a piston received in each of said cylindrical extension bores, a reciprocating drive means coupled to each of said pistons, a pair of substantially laterally disposed extension passageways extending through each of said cylinder block housings, each extension passageway having a drive housing abutting portion disposed in continuation with and communicating with one of the laterally disposed passageways of said drive housing, an inlet valve assembly inserted in one of said extension passageways within each cylinder block housing, and an outlet valve assembly inserted in the other of said extension passageways within each cylinder block housing; c. a housing head secured over the cylinder bore and each of said laterally disposed extension passageways along the outer flat surface of the cylinder block housing, each housing head having a flat forward area along and adjacent portions of the periphery thereof and a rearwardly recessed area inscribed within said flat forward area and providing communication between said pair of passageways and said cylindrical bore; d. each laterally disposed extension passageway having a portion abutting said inlet and outlet valve assemblies at marginal portions thereof whereby to hold the valve assemblies in their inserted positions within said cylinder block housing without additional fastening means; and e. venting means being provided along said opposed surfaces of said drive housing portion which extend between the base of said piston receiving bores and the exterior of said pump housing at a point adjacent the base of a piston in bottom dead-center disposition.

Claim 19

A piston type pump comprising: a. a crankcase drive housing portion having a pair of opposed flat surfaces, a cylindrical bore extending through said drive housing portion and communicating with the medial open portion of said drive housing, said medial open portion constituting a lateral drive receiving enlargement disposed at an intermediate portion of said bore, at least two laterally disposed passageways each extending through said opposed flat surfaces disposed on opposite sides of said cylindrical bore, an inlet port communicating with one of said passageways and an outlet port communicating with the other of said passageways, each of said passageways having a certain predetermined diameter at said opposed flat surfaces; b. at least two cylinder block housings each having inner and outer opposed flat surfaces secured to said drive housing along the opposed surfaces of said drive housing, each of said cylinder block housings having a cylindrical extension bore disposed coaxially with the cylindrical bore formed in said drive housing with a diameter at least equal to the diameter of said cylindrical bore, a piston received in each of said cylindrical extension bores, a reciprocating drive means coupled to each of said pistons, a pair of substantially laterally disposed extension passageways extending through each of said cylinder block housings, each extension passageway having a drive housing abutting portion disposed in continuation with and communicating with one of the laterally disposed passageways of said drive housing, an inlet valve assembly inserted in one of said extension passageways within each cylinder block housing, and an outlet valve assembly inserted in the other of said extension passageways within each cylinder block housing; c. a housing head secured over the cylinder bore and each of said laterally disposed extension passageways along the outer flat surface of the cylinder block housing, each housing head having a flat forward area along and adjacent portions of the periphery thereof and a rearwardly recessed area inscribed within said flat forward area and providing communication between said pair of passageways and said cylindrical bore; d. each laterally disposed extension passageway having a portion abutting said inlet and outlet valve assemblies at marginal portions thereof whereby to hold the valve assemblies in their inserted positions within said cylinder block housing without additional fastening means; and e. venting means being provided along said opposed surfaces of said drive housing portion which extend between the base of said piston receiving bores and the exterior of said pump housing at a point adjacent the base of a piston in bottom dead-center disposition.

Claim 20

A piston type pump comprising: a. a crankcase drive housing portion having a pair of opposed flat surfaces, a cylindrical bore extending through said drive housing portion and communicating with the medial open portion of said drive housing, said medial open portion constituting a lateral drive receiving enlargement disposed at an intermediate portion of said bore, at least two laterally disposed passageways each extending through said opposed flat surfaces disposed on opposite sides of said cylindrical bore, an inlet port communicating with one of said passageways and an outlet port communicating with the other of said passageways, each of said passageways having a certain predetermined diameter at said opposed flat surfaces; b. at least two cylinder block housings each having inner and outer opposed flat surfaces secured to said drive housing along the opposed surfaces of said drive housing, each of said cylinder block housings having a cylindrical Extension bore disposed coaxially with the cylindrical bore formed in said drive housing with a diameter at least equal to the diameter of said cylindrical bore, a piston received in each of said cylindrical extension bores, a reciprocating drive means coupled to each of said pistons, a pair of substantially laterally disposed extension passageways extending through each of said cylinder block housings, each extension passageway having a drive housing abutting portion disposed in continuation with and communicating with one of the laterally disposed passageways of said drive housing, an inlet valve assembly inserted in one of said extension passageways within each cylinder block housing, and an outlet valve assembly inserted in the other of said extension passageways within each cylinder block housing; c. a housing head secured over the cylinder bore and each of said laterally disposed extension passageways along the outer flat surface of the cylinder block housing, each housing head having a flat forward area along and adjacent portions of the periphery thereof and a rearwardly recessed area inscribed within said flat forward area and providing communication between said pair of passageways and said cylindrical bore; d. each laterally disposed extension passageway having a portion abutting said inlet and outlet valve assemblies at marginal portions thereof whereby to hold the valve assemblies in their inserted positions within said cylinder block housing without additional fastening means; and e. each of said pistons being coupled to a reciprocating drive means by a cam follower means, a centrally disposed drive yoke coupling said cam follower means, one to another, and a central shaft disposed coaxially with said pistons and cam follower means for threadably coupling each of said pistons to its associated cam follower means, the outer surface of each of said pistons having a slot formed therein to assist in arcuate rotation of said pistons.

Claim 21

A piston type pump comprising: a. a crankcase drive housing portion having a pair of opposed flat surfaces, a cylindrical bore extending through said drive housing portion and communicating with the medial open portion of said drive housing, said medial open portion constituting a lateral drive receiving enlargement disposed at an intermediate portion of said bore, at least two laterally disposed passageways each extending through said opposed flat surfaces disposed on opposite sides of said cylindrical bore, an inlet port communicating with one of said passageways and an outlet port communicating with the other of said passageways, each of said passageways having a certain predetermined diameter at said opposed flat surfaces; b. at least two cylinder block housings each having inner and outer opposed flat surfaces secured to said drive housing along the opposed surfaces of said drive housing, each of said cylinder block housings having a cylindrical Extension bore disposed coaxially with the cylindrical bore formed in said drive housing with a diameter at least equal to the diameter of said cylindrical bore, a piston received in each of said cylindrical extension bores, a reciprocating drive means coupled to each of said pistons, a pair of substantially laterally disposed extension passageways extending through each of said cylinder block housings, each extension passageway having a drive housing abutting portion disposed in continuation with and communicating with one of the laterally disposed passageways of said drive housing, an inlet valve assembly inserted in one of said extension passageways within each cylinder block housing, and an outlet valve assembly inserted in the other of said extension passageways within each cylinder block housing; c. a housing head secured over the cylinder bore and each of said laterally disposed extension passageways along the outer flat surface of the cylinder block housing, each housing head having a flat forward area along and adjacent portions of the periphery thereof and a rearwardly recessed area inscribed within said flat forward area and providing communication between said pair of passageways and said cylindrical bore; d. each laterally disposed extension passageway having a portion abutting said inlet and outlet valve assemblies at marginal portions thereof whereby to hold the valve assemblies in their inserted positions within said cylinder block housing without additional fastening means; and e. each of said pistons being coupled to a reciprocating drive means by a cam follower means, a centrally disposed drive yoke coupling said cam follower means, one to another, and a central shaft disposed coaxially with said pistons and cam follower means for threadably coupling each of said pistons to its associated cam follower means, the outer surface of each of said pistons having a slot formed therein to assist in arcuate rotation of said pistons.

Claim 22

A piston and yoke assembly for a fluid pump having a pair of longitudinally spaced cylinder means disposed on a common axis and a drive shaft journaled on an axis disposed between said cylinder means and normal to said common axis, and eccentric drive means on said shaft, said assembly comprising: a. a rigid generally U-shaped yoke comprising an elongated relatively soft metallic strap bent to form a generally flat body portion extending generally parallel to said common axis and a pair of opposed parallel side portions at the opposite ends of, and normal to, the body portion, said side portions having aligned openings therethrough generally on said common axis; b. a pair of opposed relatively hard bearing shoes each having a head disposed between said yoke side portions and abutting an adjacent one of said side portions, and a shank received in an adjacent one of said openings, said heads having opposed flat parallel wear surfaces for engagement with said eccentric drive means; c. a pair of tubular piston rods mounted and guided in said cylinder means and having inner ends each receiving an adjacent one of said bearing shoe shanks and abutting the adjacent yoke side portion opposite the adjacent bearing shoe head, and outer ends; d. piston means on the outer ends of said piston rods; and e. a pair of anchoring screw means each extending axially through a different one of said piston means and a cooperating piston rod, and each having screw-threaded engagement with an adjacent bearing shoe shank, whereby to releasably anchor said yoke, bearing shoes, piston rods and the piston means together.

Claim 23

A piston and yoke assembly for a fluid pump having a pair of longitudinally spaced cylinder means disposed on a common axis and a drive shaft journaled on an axis disposed between said cylinder means and normal to said common axis, and eccentric drive means on said shaft, said assembly comprising: a. a rigid generally U-shaped yoke comprising an elongated relatively soft metallic strap bent to form a generally flat body portion extending generally parallel to said common axis and a pair of opposed parallel side portions at the opposite ends of, and normal to, the body portion, said side portions having aligned openings therethrough generally on said common axis; b. a pair of opposed relatively hard bearing shoes each having a head disposed between said yoke side portions and abutting an adjacent one of said side portions, and a shank received in an adjacent one of said openings, said heads having opposed flat parallel wear surfaces for engagement with said eccentric drive means; c. a pair of tubular piston rods mounted and guided in said cylinder means and having inner ends each receiving an adjacent one of said bearing shoe shanks and abutting the adjacent yoke side portion opposite the adjacent bearing shoe head, and outer ends; d. piston means on the outer ends of said piston rods; and e. a pair of anchoring screw means each extending axially through a different one of said piston means and a cooperating piston rod, and each having screw-threaded engagement with an adjacent bearing shoe shank, whereby to releasably anchor said yoke, bearing shoes, piston rods and the piston means together.

Claim 24

The piston and yoke assembly for a fluid pump as defined in claim 15 wherein each of said cylinder means includes a sleeve insert member.

Claim 25

The piston and yoke assembly for a fluid pump as defined in claim 15 wherein said eccentric drive means comprises a bearing member having an outer race and being mounted upon said drive shaft eccentrically to the central axis of said drive shafT and wherein said outer race is in contact with the said opposed flat parallel wear surfaces of said bearing shoes.

Claim 26

The piston and yoke assembly for a fluid pump as defined in claim 15 wherein said piston and yoke assembly is mounted within a pump body and wherein said eccentric drive means is disposed within a central crankcase portion of said pump body.

Claim 27

The piston and yoke assembly for a fluid pump as defined in claim 18 wherein seal elements are disposed within said pump body and circumferentially engage said piston rods.

Claim 28

The piston and yoke assembly for a fluid pump as defined in claim 16 being particularly characterized in that each of said piston means includes cup means in engagement with the inner periphery of said sleeve insert member.