Hydraulic system with improved changeover control unit

Claim 2

In a hydraulic system, a reversible fluid-driven motor, a source of pressure fluid for rotationally driving said motor, conduit means connecting said source of pressure fluid and said reversible motor comprising a pressure line to said motor and a discharge line from said motor, a changeover valve connected to said conduit means for reversing direction of rotation of said motor, means defining a variable restriction restricting fluid flow in said discharge line variably opened and closed in response to change of settings of said changeover valve to different operating position, a metering valve connected to said conduit means responsive to fluid pressure changes across said restriction bypassing at least some flow of fluid from said pressure line upstream of said motor to said discharge line in dependence upon pressure changes across said restriction, and said means defining said restriction comprising means responsive to pressure changes in said Pressure line increasing opening of said restriction in response to increases of pressure in said pressure line.

Claim 3

In a hydraulic system, a reversible fluid-driven motor, a source of pressure fluid for rotationally driving said motor, conduit means connecting said source of pressure fluid and said reversible motor comprising a pressure line to said motor and a discharge line from said motor, a changeover valve connected to said conduit means for reversing direction of rotation of said motor, means defining a variable restriction restricting fluid flow in said discharge line variably opened and closed in response to change of settings of said changeover valve to different operating positions, a metering valve connected to said conduit means responsive to fluid pressure changes across said restriction bypassing at least some flow of fluid from said pressure line upstream of said motor to said discharge line in dependence upon pressure changes across said restriction, said changeover Valve, said metering valve, and said means defining said restriction comprises at least some common parts defining jointly a unitary control device, control device comprising a plurality of coaxial sleeves relatively rotatable, one of said sleeves having a plurality of grooves providing communication between said pressure line, said motor and said discharge line for driving the motor in opposite direction, said means defining said restriction comprising means on another of said sleeves variably restricting flow through one of said grooves upon relative rotation of said sleeves, and means for relatively rotating said sleeves.

Claim 4

In a hydraulic system, a reversible fluid-driven motor, a source of pressure fluid for rotationally driving said motor, conduit means connecting said source of pressure fluid and said reversible motor comprising a pressure line to said motor and a discharge line from said motor, a changeover valve connected to said conduit means for reversing direction of rotation of said motor, means defining a variable restriction restricting fluid flow in said discharge line variably opened and closed in response to change of settings of said changeover valve to different operating positions, a metering valve connected to said conduit means responsive to fluid pressure changes across said restriction bypassing at least some flow of fluid from said pressure line upstream of said motor to said discharge line in dependence upon pressure changes across said restriction, said changeover Valve, said metering valve, and said means defining said restriction comprises at least some common parts defining jointly a unitary control device, control device comprising a plurality of coaxial sleeves relatively rotatable, one of said sleeves having a plurality of grooves providing communication between said pressure line, said motor and said discharge line for driving the motor in opposite direction, said means defining said restriction comprising means on another of said sleeves variably restricting flow through one of said grooves upon relative rotation of said sleeves, and means for relatively rotating said sleeves.

Claim 5

In a hydraulic system according to claim 2, in which said metering valve comprises a piston reciprocable in an innermost of said sleeves in response to variations in pressure drop across said restriction.

Claim 6

In a hydraulic system according to claim 3, in which a outermost of said sleeves defines said changeover valve and is axially movable relative to the other of said sleeves.

Claim 7

In a hydraulic system according to claim 4, including a manually actuated cam axially displacing said outermost sleeve.

Claim 8

In a hydraulic system according to claim 5, in which said cam comprises an eccentric pin received in a recess in said outermost sleeve, and a resilient ring about said pin.

Claim 9

In a hydraulic system, a reversible fluid-driven motor, a source of pressure fluid for rotationally driving said motor, conduit means connecting said source of pressure fluid and said reversible motor comprising a pressure line to said motor and a discharge line from said motor, a changeover valve connected to said conduit means for reversing direction of rotation of said motor, means defining a variable restriction restricting fluid flow in said discharge line variably opened and closed in response to change of settings of said changeover valve to different operating positions, a metering valve connected to said conduit means responsive to fluid pressure changes across said restriction bypassing at least some flow of fluid from said pressure line upstream of said motor to said discharging line in dependence upon pressure changes across said restriction and said changeover valve comprising two concentric sleeves relatively rotatable, defining said means defining said restriction, one of said sleeves having a groove defining in communication with said discharge line, the other sleeve having means variably controlling flow through said groove in dependence upon the relative angular positions of said sleeves.

Claim 10

In a hydraulic system, a reversible fluid-driven motor, a source of pressure fluid for rotationally driving said motor, conduit means connecting said source of pressure fluid and said reversible motor comprising a pressure line to said motor and a discharge line from said motor, a changeover valve connected to said conduit means for reversing direction of rotation of said motor, means defining a variable restriction restricting fluid flow in said discharge line variably opened and closed in response to change of settings of said changeover valve to different operating positions, a metering valve connected to said conduit means responsive to fluid pressure changes across said restriction bypassing at least some flow of fluid from said pressure line upstream of said motor to said discharging line in dependence upon pressure changes across said restriction and said changeover valve comprising two concentric sleeves relatively rotatable, defining said means defining said restriction, one of said sleeves having a groove defining in communication with said discharge line, the other sleeve having means variably controlling flow through said groove in dependence upon the relative angular positions of said sleeves.

Claim 11

In a hydraulic system according to claim 7, in which said one sleeve comprises other grooves providing flow paths in said changeover valve for effecting changeover of flow of fluid to said motor thereby to reverse direction of rotation thereof.

Claim 12

In a hydraulic system according to claim 8, in which said metering valve comprises a piston reciprocable internally of said concentric sleeves, and means providing communication of one side of the piston with fluid uPstream of said restriction and an opposite side of the piston with fluid downstream of said restriction variably moving said piston in response to changes in pressure drop across said restriction.