Reciprocatory motors

Claim 2

A fluid pressure operated reciprocatory motor, comprising: a piston axially slidable in a piston cylinder, said piston having opposed working faces of different effective areas, its smaller effective area communicating with a constant pressure piston chamber in permanent communication with a source of fluid pressure to bias said piston in one sense of axial direction, and its larger effective area communicating with an alternating pressure piston chamber; control means alternately connecting said alternating pressure piston chamber with a source of fluid pressure and with exhaust for imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder and said spool cylinder communicating with said piston cylinder; means biasing said spool axially in its cylinder towards said piston cylinder; a cam surface provided on said piston; an abutment surface provided on said spool, said abutment surface abutting said cam surface and being urged into engAgement therewith by said biasing means whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; and wherein thrust means is located between said piston and said piston cylinder for providing a radially directed force on said piston which force opposes, and is substantially equal to, the radial force exerted on said piston by said biasing means through said spool.

Claim 3

A motor as claimed in claim 1, further comprising recess means provided between said piston and piston cylinder, said thrust means being adapted to comprise fluid pressure pad means located by and forced in said recess means; and passage means which communicates between said constant pressure piston chamber and said recess means for supplying fluid under pressure between said recess means and said constant pressure piston chamber.

Claim 4

A motor as claimed in claim 1, in which said biasing means is adapted to be provided by fluid under pressure acting on said spool and wherein said spool has a working face which communicates with a spool chamber and passage means is provided which communicates between said constant pressure piston chamber and said spool chamber for supplying fluid under pressure between said spool chamber and said constant pressure piston chamber whereby said spool is biased axially under such fluid pressure to urge said abutment and cam surfaces into engagement.

Claim 5

A fluid pressure operated reciprocatory motor, comprising: a substantially cylindrical piston axially slidable in a piston cylinder; means restraining rotation of said piston about its axis relative to said piston cylinder; fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder and said spool cylinder communicating with said piston cylinder; means biasing said spool axially in its cylinder towards said piston cylinder; a cam surface provided on said piston, said cam surface having a flat extending axially of said piston in a predetermined profile with respect to the piston axis, the abutment surface of said spool engaging with said flat to restrain rotation of said piston in said piston cylinder; an abutment surface provided on said spool, said abutment surface abutting said cam surface and being urged into engagement therewith by said biasing means whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; and wherein thrust means is located between said piston and said piston cylinder for providing a radially directed force on said piston which force opposes, and is substantially equal to, the radial force exerted on the said piston by said biasing means through said spool.

Claim 6

A fluid pressure operated reciprocatory motor, comprising: a substantially cylindrical piston axially slidable in a piston cylinder; means restraining rotation of said piston about its axis relative to said piston cylinder; fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder and said spool cylinder communicating with said piston cylinder; means biasing said spool axially in its cylinder towards said piston cylinder; a cam surface provided on said piston, said cam surface having a flat extending axially of said piston in a predetermined profile with respect to the piston axis, the abutment surface of said spool engaging with said flat to restrain rotation of said piston in said piston cylinder; an abutment surface provided on said spool, said abutment surface abutting said cam surface and being urged into engagement therewith by said biasing means whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; and wherein thrust means is located between said piston and said piston cylinder for providing a radially directed force on said piston which force opposes, and is substantially equal to, the radial force exerted on the said piston by said biasing means through said spool.

Claim 7

A fluid pressure operated reciprocatory motor, comprising a piston axially slidable in a piston cylinder; fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder and said spool cylinder communicating with said piston cylinder; means biasing said spool axially in its cylinder towards said piston cylinder; a cam surface provided on said piston; an abutment surface provided on said spool, said abutment surface abutting said cam surface and being urged into engagement therewith by said biasing means whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; and wherein thrust means is located between said piston and said piston cylinder for providing a radially directed force on said pistoN which force opposes, and is substantially equal to, the radial force exerted on said piston by said biasing means through said spool; and further comprising in combination with a frame, a housing in which said spool cylinder and piston cylinder are commonly defined, and wherein said spool extends through its cylinder from said housing and is attached to said frame to mount said motor on said frame whereby, during reciprocation of said piston in its cylinder, said housing exhibits movement relative to said spool and frame in the direction of the axis of said spool and an end of said piston exhibits a compound motion relative to said frame as a result of reciprocation of said piston in the direction of its axis and movement of said housing in the direction of the axis of said spool.

Claim 8

A fluid pressure operated reciprocatory motor, comprising a piston axially slidable in a piston cylinder; fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder and said spool cylinder communicating with said piston cylinder; means biasing said spool axially in its cylinder towards said piston cylinder; a cam surface provided on said piston; an abutment surface provided on said spool, said abutment surface abutting said cam surface and being urged into engagement therewith by said biasing means whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; and wherein thrust means is located between said piston and said piston cylinder for providing a radially directed force on said pistoN which force opposes, and is substantially equal to, the radial force exerted on said piston by said biasing means through said spool; and further comprising in combination with a frame, a housing in which said spool cylinder and piston cylinder are commonly defined, and wherein said spool extends through its cylinder from said housing and is attached to said frame to mount said motor on said frame whereby, during reciprocation of said piston in its cylinder, said housing exhibits movement relative to said spool and frame in the direction of the axis of said spool and an end of said piston exhibits a compound motion relative to said frame as a result of reciprocation of said piston in the direction of its axis and movement of said housing in the direction of the axis of said spool.

Claim 9

A fluid pressure operated reciprocatory motor, comprising: a piston axially slidable in a piston cylinder; fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder and with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder; a cam surface provided on said piston; an abutment surface provided on said spool, said abutment surface abutting said cam surface; means biasing said spool axially in its cylinder and said abutment surface into engagement with said cam surface, whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; a working face on said spool communicating with a spool chamber; means connecting said spool chamber to a source of fluid pressure, said fluid pressure providing said biasing means to act on said working face; recess means between said piston and said piston cylinder and located on the side of said piston remote from the position of engagement between said cam surface and said abutment surface, said recess means providing a location for fluid pressure pad means and having an effective area which is substantially equal to the area of said spool working face; and passage means communicating between said recess means and said spool chamber through which fluid pressure in said spool chamber and said recess means is equalized whereby, with fluid pressure in said spool chamber and in said recess means, radially directed forces on said piston applied by said abutment surface of the spool and fluid pressure pad means formed in said recess means are substantially equal and opposite.

Claim 10

A fluid pressure operated reciprocatory motor, comprising: a piston axially slidable in a piston cylinder; fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder and with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder; a cam surface provided on said piston; an abutment surface provided on said spool, said abutment surface abutting said cam surface; means biasing said spool axially in its cylinder and said abutment surface into engagement with said cam surface, whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; a working face on said spool communicating with a spool chamber; means connecting said spool chamber to a source of fluid pressure, said fluid pressure providing said biasing means to act on said working face; recess means between said piston and said piston cylinder and located on the side of said piston remote from the position of engagement between said cam surface and said abutment surface, said recess means providing a location for fluid pressure pad means and having an effective area which is substantially equal to the area of said spool working face; and passage means communicating between said recess means and said spool chamber through which fluid pressure in said spool chamber and said recess means is equalized whereby, with fluid pressure in said spool chamber and in said recess means, radially directed forces on said piston applied by said abutment surface of the spool and fluid pressure pad means formed in said recess means are substantially equal and opposite.

Claim 11

A motor as claimed in claim 6, in which said recess means comprises a part annular recess defined in said piston cylinder and located in diametrical alignment with said position of engagement between said cam surface and said abutment surface.

Claim 12

A motor as claimed in claim 6, in which said recess means comprises a part annular recess defined in the peripheral surface of said piston and located in diametrical alignment with said cam surface.

Claim 13

A motor as claimed in claim 6, wherein said piston has opposed working faces of different effective areas, its smaller effective area communicating with a constant pressure piston chamber in permanent communication with a source of fluid pressure to bias said piston in one sense of axial direction and its larger effective area communicating with an alternating pressure piston chamber; said motor further comprising control means alternately connecting said alternating pressure piston chamber with a source of fluid pressure and with exhaust to reciprocate said piston.

Claim 14

A motor as claimed in claim 9, wherein said recess means and said spool chamber communicate by way of passage means with said constant pressure piston chamber.

Claim 15

A motor as claimed in claim 6, in which said piston is substantially cylindrical and has a cam surface comprising a flat extending axially of said piston in predetermined profile with respect to the piston axis, the abutment surface of said spool engaging with said flat to restrain rotation of said piston in said piston cylinder.

Claim 16

A motor as claimed in claim 6, comprising in combination with a frame, a housing in which said spool cylinder and piston cylinder are commonly defined, and wherein said spool extends through its cylinder from said housing and is attached to said frame to mount said motor on said frame whereby, during reciprocation of said piston in its cylinder, said housing moves relative to said spool and frame in the direction of the axis of said spool and an end of said piston exhibits a compound motion relative to said frame as a result of reciprocation of said piston in the direction of its axis and movement of said housing in the direction of the axis of said spool.

Claim 17

A fluid pressure operated reciprocatory motor which comprises: a piston axially slidable in a piston cylinder; said piston including fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder and with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder; a cam surface provided on said piston; an abutment surface provided on said spool, said abutment surface abutting said cam surface; means biasing said spool axially in its cylinder and said abutment surface into engagement with said cam surface whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; thrust means between said piston and said piston cylinder and located on the side of said piston remote from the position of engagement between said cam surface and said abutment surface, said thrust means providing a radially directed force on said piston which opposes the radially directed force on said piston applied by said abutment surface of the spool; and means interconnecting said biasing means and said thrust means and maintaining the radially directed force applied on said piston by said thrust means substantially equal to the opposed radially directed force applied on the piston by said biasing means through said abutment surface.

Claim 18

A fluid pressure operated reciprocatory motor which comprises: a piston axially slidable in a piston cylinder; said piston including fluid pressure operated means imparting reciprocatory movement to said piston in its cylinder; a spool axially slidable in a spool cylinder, said spool cylinder being fixedly located with respect to said piston cylinder and with the axis of said spool cylinder disposed substantially radially with respect to said piston cylinder; a cam surface provided on said piston; an abutment surface provided on said spool, said abutment surface abutting said cam surface; means biasing said spool axially in its cylinder and said abutment surface into engagement with said cam surface whereby, during reciprocation of said piston, said abutment surface rides over said cam surface to impart axial movement to said spool; thrust means between said piston and said piston cylinder and located on the side of said piston remote from the position of engagement between said cam surface and said abutment surface, said thrust means providing a radially directed force on said piston which opposes the radially directed force on said piston applied by said abutment surface of the spool; and means interconnecting said biasing means and said thrust means and maintaining the radially directed force applied on said piston by said thrust means substantially equal to the opposed radially directed force applied on the piston by said biasing means through said abutment surface.