Fluid pressure operated motors

Claim 2

A fluid pressure operated motor which includes a housing; a sleeve cylinder defined by the housing; a cylindrical sleeve located in the sleeve cylinder and capable of axial sliding movement therein; means for axially adjusting the sleeve in its cylinder; locking means for securing the sleeve relative to the housing; a piston cylinder defined by the sleeve; a piston located in the piston cylinder to extend Axially therethrough and capable of axial sliding movement therein; and fluid pressure operated means for imparting reciprocal movement to the piston in its axial direction; wherein the piston cylinder is provided with control ports which are adapted to be controlled by lands of the piston during reciprocation of the piston to determine the axial length of stroke of the piston imparted by the fluid pressure operated means and wherein the sleeve can be axially adjusted in its cylinder and secured by the locking means to adjust the center of oscillation of the piston relative to the housing.

Claim 3

A fluid pressure operated motor as claimed in claim 1 wherein said locking means is adapted to comprise a fluid pressure pad and recess means is provided between the sleeve cylinder and sleeve, which recess means is adapted to communicate alternatively with fluid pressure or exhaust whereby, with fluid pressure in said recess means, a radially directed force is imparted between the sleeve and its cylinder to secure the sleeve relative to the housing.

Claim 4

A fluid pressure operated motor as claimed in claim 1 wherein the piston is capable of engagement with the sleeve during axial movement of the piston in its cylinder in one sense of axial direction at a position which substantially corresponds to the end of stroke of the piston in said one sense of axial direction and sleeve adjustment means is provided which overrides said means for imparting reciprocal movement to the piston and is adapted to impart controlled axial movement to the piston in said one sense of axial direction whilst the piston and sleeve are in engagement to adjust the axial position of the sleeve in its cylinder and thereby adjust the end of stroke of the piston axially relative to the housing.

Claim 5

A fluid pressure operated motor as claimed in claim 3 wherein the piston is capable of engagement with the sleeve during axial movement of the piston in its cylinder in the opposite sense of axial direction at a position subsequent to and axially remote from the end of stroke of the piston in said opposite sense of axial direction and the sleeve adjustment means is adapted to impart controlled axial movement to the piston in said opposite sense of axial direction to adjust the axial position of the sleeve in its cylinder from which position the sleeve can be axially reset by controlled movement of the piston in said one sense of axial direction.

Claim 6

A fluid pressure operated motor as claimed in claim 1 wherein two pressure chambers are provided, one pressure chamber being adapted to alternately contract and expand and the other pressure chamber being adapted simultaneously to alternately expand and contract respectively during reciprocation of the piston; the piston having piston land means which controls the opening and closing of two axially spaced control ports in the piston cylinder and in which a first pressure chamber, during its contraction by movement of the piston in one sense of axial direction, is adapted to exhaust through a first control port controlled by the piston land means and the end of stroke of the piston in said one sense of axial direction is determined by the first control port being closed by the piston land means; and the second pressure chamber, having its contraction by movement of the piston in the opposite sense of axial direction is adapted to exhaust through the second control port controlled by the piston land means, the end of stroke of the piston in the opposite sense of axial direction being determined by said second control port being closed by the piston land means.

Claim 7

A fluid pressure operated motor as claimed in claim 5 wherein the piston has two axially spaced lands which, together with the piston cylinder, define an exhaust chamber which is adapted to communicate with the contracting pressure chamber during axial movement of the piston; the first of said control ports being controlled by a first piston land so that it is alternately opened and closed to communication with the eXhaust chamber and the second of said control ports being controlled by the second piston land so that it is alternately opened and closed to communication with the exhaust chamber, said control ports and piston lands being arranged so that at least one or other of said control ports is always open to communication with the exhaust chamber during reciprocation of the piston, the first pressure chamber, when contracting, being adapted to exhaust by way of said exhaust chamber and the first control port, the end of stroke of the piston in the one sense of axial direction being determined when the first control port is closed by the first piston land, and the second pressure chamber, when contracting, being adapted to exhaust by way of said exhaust chamber and the second control port, the end of stroke of the piston in the opposite sense of axial direction being determined when the second control port is closed by the second piston land; and wherein valve means is provided which, in a first operative condition is adapted to close communication between the second control port and exhaust and to open communication between the first control port and exhaust when the piston is moving in said one sense of axial direction, and in a second operative condition, is adapted to close communication between said first control port and exhaust and to open communication between said second control port and exhaust when the piston is moving in the opposite sense of axial direction.

Claim 8

A fluid pressure operated motor as claimed in claim 6 in which the piston is capable of engagement with the sleeve during axial movement of the position in its cylinder in one sense of axial direction at a position which substantially corresponds to the end of stroke of the piston in one sense of axial direction and sleeve adjustment means is provided which overrides said means for imparting reciprocal movement to the piston and is adapted to impart controlled axial movement to the piston in said one sense of axial direction while the piston and sleeve are in engagement to adjust the axial position of the sleeve in its cylinder and thereby adjust the end of stroke of the piston axially relative to the housing and, wherein the piston is adapted to engage with the sleeve during controlled axial movement of the piston in one sense of axial direction at a position which substantially corresponds to the first control port being closed by the first piston land.

Claim 9

A fluid pressure operated motor as claimed in claim 7 wherein the sleeve carries a peg which projects into the exhaust chamber and during controlled axial movement of the sleeve in said one sense of axial direction the first piston land is adapted to engage with the peg to move the sleeve axially within its cylinder in said one sense of axial direction.

Claim 10

A fluid pressure operated motor as claimed in claim 5 wherein the piston and said pressure chambers constitute a double acting device and further valve means is provided having a first operative condition in which the second pressure chamber is adapted to communicate with fluid pressure and the first pressure chamber is adapted to communicate with exhaust by way of the first control port and a second operative condition in which the first pressure chamber is adapted to communicate with fluid pressure and the second pressure chamber is adapted to communicate with exhaust by way of the second control port and the piston is caused to reciprocate in its cylinder by adjustment of said further valve means from its first operative condition to its second operative condition and vice versa.

Claim 11

A fluid pressure operated motor as claimed in claim 5 wherein an axially disposed array of ports are provided in the piston cylinder and port selection means is provided by which at least one port in said array can be selected as the second control port for communication with exhaust and the end of stroke of the piston in said opposite sense of axial direction is determined when the selected port or ports of said array Is closed by said piston land means.

Claim 12

A fluid pressure operated motor as claimed in claim 5 in which the piston is capable of engagement with the sleeve during axial movement of the piston in its cylinder in one sense of axial direction at a position which substantially corresponds to the end of stroke of the piston in one sense of axial direction and sleeve adjustment means is provided which overrides said means for imparting reciprocal movement to the piston and is adapted to impart controlled axial movement to the piston in said one sense of axial direction while the piston and sleeve are in engagement to adjust the axial position of the sleeve in its cylinder and thereby adjust the end of stroke of the piston axially relative to the housing, and wherein said sleeve adjustment means comprises a selector valve operatively associated with the two pressure chambers and having a first condition in which the first pressure chamber can be connected to fluid pressure and the second pressure chamber can be simultaneously opened to exhaust to impart controlled movement to the piston in said opposite sense of axial direction and a second condition in which the second pressure chamber can be connected to fluid pressure and the first pressure chamber can simultaneously be opened to exhaust to impart controlled movement to the piston in said one sense of axial direction.