Position control for parallel hydraulic systems

Claim 2

A hydraulic control system comprising: a plurality of hydraulic motors, each of the motors including a cylinder having rod and anchor ends and a rod reciprocally mounted in the cylinder and projecting from the rod end thereof; fluid line means connecting the anchor ends of the cylinders in parallel; additional fluid line means connected to the first mentioned fluid line means and being selectively connectable to a source of fluid pressure and a fluid reservoir; valve means movable between open and closed positions and normally biased toward the open position interposed in the additional fluid line means; and means responsive to the retraction of the rod of one of the motors to a predetermined position to move the valve means to the closed position.

Claim 3

The hydraulic control system set forth in claim 1 wherein the valve means includes means responsive to fluid pressure within the anchor ends of cylinders when the valve means is moved to the closed position to retain the valve means in the closed position until the additional fluid line means is connected to the source of fluid pressure.

Claim 4

The control system set forth in claim 1 wherein the means to move the valve means to the closed position includes first and second support members carried by the rod and cylinder respectively of the one motor, a push rod slidably mounted on the support members for longitudinal movement, a stop member mounted on the push rod intermediate the support member, and spring means encircling the push rod intermediate the first support member and the stop member, and wherein the valve means is mounted on the cylinder of the one motor adjacent the end of the push rod, whereby, upon retraction of the rod of the one motor, the spring means will be compressed between the first support member and the stop member and bias the push rod into engagement with the valve means to move the valve means to the closed position.

Claim 5

A hydraulic control system comprising: a plurality of double-acting extensible and retractable hydraulic motors including cylinders having rod and anchor ends and rods reciprocally mounted therein and extending from the rod ends thereof; first fluid line means connecting the anchor ends of the cylinders in parallel; second fluid line means connecting the rod ends of the cylinders in parallel; third and fourth fluid line means connected respectively to the first and second fluid line means and being connectable alternately to a source of fluid pressure and a fluid reservoir whereby the rods can be extended or retracted by connecting the third and fourth fluid lines respectively to the source of fluid pressure; valve means movable between open and closed positions interposed in one of the third and fourth fluid line means and means responsive to the movement of the rod of one of the motors in a direction to exhaust fluid through the one fluid line to move the valve means to the closed position upon the rod of the one motor reaching a predetermined position; whereby, upon the valve means being moved to the closed position any movement of one or more of the rods must be accompanied by movement of one or more of the rods in an opposite direction.

Claim 6

A hydraulic control system comprising: a plurality of double-acting extensible and retractable hydraulic motors including cylinders having rod and anchor ends and rods reciprocally mounted therein and extending from the rod ends thereof; first fluid line means connecting the anchor ends of the cylinders in parallel; second fluid line means connecting the rod ends of the cylinders in parallel; third and fourth fluid line means connected respectively to the first and second fluid line means and being connectable alternately to a source of fluid pressure and a fluid reservoir whereby the rods can be extended or retracted by connecting the third and fourth fluid lines respectively to the source of fluid pressure; valve means movable between open and closed positions interposed in one of the third and fourth fluid line means and means responsive to the movement of the rod of one of the motors in a direction to exhaust fluid through the one fluid line to move the valve means to the closed position upon the rod of the one motor reaching a predetermined position; whereby, upon the valve means being moved to the closed position any movement of one or more of the rods must be accompanied by movement of one or more of the rods in an opposite direction.

Claim 7

The hydraulic control system set forth in claim 4 wherein the means to move the valve means to the closed position is adjustable to vary the position of the rod of the one motor at which the valve means will be closed.

Claim 8

The hydraulic control system set forth in claim 4 wherein the valve means includes means responsive to fluid pressure in the one fluid line means to move to the open position when the one fluid line means is connected to the source of fluid pressure.

Claim 9

A hydraulic control system comprising: a plurality of hydraulic motors each including a cylinder having rod and anchor ends and a rod reciprocally mounted within the cylinder and projecting from the rod end thereof; first fluid line means connecting the anchor ends of the cylinders in parallel, second fluid line means connecting the rod ends of the cylinders in parallel; third and fourth fluid line means connected respectively to the first and second fluid line means and being connectable alternately to a source of fluid pressure and a fluid reservoir whereby the rods can be extended and retracted by connecting the third and fourth fluid line means respectively to the source of fluid pressure; valve means movable between open and closed positions interposed in the third fluid line means; the valve means including means responsive to fluid pressure in the third fluid line means to move the valve means to the open position when the third fluid line means is connected to the source of fluid pressure; and means responsive to the retraction of the rod of one of the motors to a predetermined position to move the valve means to the closed position whereby additional movement of one or more of the rods is accompanied by movement of one or more of the other rods in an opposite direction.

Claim 10

A hydraulic control system comprising: a plurality of hydraulic motors each including a cylinder having rod and anchor ends and a rod reciprocally mounted within the cylinder and projecting from the rod end thereof; first fluid line means connecting the anchor ends of the cylinders in parallel, second fluid line means connecting the rod ends of the cylinders in parallel; third and fourth fluid line means connected respectively to the first and second fluid line means and being connectable alternately to a source of fluid pressure and a fluid reservoir whereby the rods can be extended and retracted by connecting the third and fourth fluid line means respectively to the source of fluid pressure; valve means movable between open and closed positions interposed in the third fluid line means; the valve means including means responsive to fluid pressure in the third fluid line means to move the valve means to the open position when the third fluid line means is connected to the source of fluid pressure; and means responsive to the retraction of the rod of one of the motors to a predetermined position to move the valve means to the closed position whereby additional movement of one or more of the rods is accompanied by movement of one or more of the other rods in an opposite direction.

Claim 11

The control system set forth in claim 7 further including means normally biasing the valve means toward the open position, and wherein the valve means includes means responsive to fluid pressure in the anchoR ends of the cylinders when the valve means is moved to the closed position to retain the valve means in the closed position until the third fluid line means is connected to the source of fluid pressure.

Claim 12

The control system set forth in claim 7 wherein the displacement of the rod and anchor ends of each of the cylinders is equal to the displacement of the rod and anchor ends respectively of the other cylinders whereby the additional movement of one or more of the rods is accompanied by equal and opposite movement of one or more of the other rods.

Claim 13

The control system set forth in claim 7 wherein the means responsive to the retraction of the one of the motors includes first and second support members mounted on the rod and cylinder respectively of the one motor, a push rod slidably carried by the support members for longitudinal movement, a stop member mounted on the push rod intermediate the support members, and means carried by the push rod between the first support member and the stop means and engageable by the first support member and the stop means, whereby retractive movement of the rod of the one motor is transferred to the push rod through the first support member, the means carried by the push rod and the stop member to move the push rod in a direction to move the valve means to the closed position.

Claim 14

The control system set forth in claim 10 wherein the stop member is adjustably mounted on the push rod.

Claim 15

The control system set forth in claim 11 wherein the means carried by the push rod and engageable by the first support member and the stop member includes compression spring means.

Claim 16

The control system set forth in claim 12 wherein the valve means includes a valve body having a bore with an enlarged area near one end, a fluid passageway intersecting the enlarged area of the bore, the valve body being interposed in the third fluid line means with the valve bore and the fluid passageway in fluid communication with the third fluid line means, a valve plunger reciprocally mounted in the valve bore and having a diameter substantially equal to the valve bore, means normally biasing the plunger to the enlarged area of the bore, and a plunger stem extending from the plunger and the valve body to a position to be contacted by the push rod.

Claim 17

The control system set forth in claim 13 wherein the portion of the valve bore leading to the enlarged area is tapered to guide the plunger when moving to the closed position.

Claim 18

The control system set forth in claim 14 wherein the valve bore is provided with an inwardly directed shoulder which engages the plunger to limit the movement of the plunger.