Variable speed hydraulic drive system

Claim 2

In an arrangement including a plurality of open tanks and a crane movable along a runway over said tanks, the improvement wherein said crane comprises hoist support means engaged on said runway for movement along a path of travel above said open tanks, said support means being actuatable through repeated cycles of acceleration, deceleration and stopping during movement along said runway to selected locations over said tanks; load hoist means carried by said support means for movement to said locations; frame means operatively connected to said hoist means and adapted to be raised and lowered by said hoist means when said support means is over a selected tank; an article container rotatably mounted on said frame means so that said container can be placed in and removed from a selected tank by raising and lowering said frame means; and a hydraulic drive system carried on said crane for actuating it through said cycles of acceleration, deceleration and stopping, said drive system including rotary fluid motor means connected to said support means for powering it along said runway and to said hoist means for raising and lowering said container, pump means, and a closed loop hydraulic circuit connecting said pump means to said motor means, said closed loop circuit defining a flow passage through which fluid is delivered from said pump means to said motor means and through which fluid delivered to said motor means is returned directly to said pump means, and said circuit being further characterized by the absence of a fluid-containing reservoir in said flow passage.

Claim 3

In an arrangement including a plurality of open tanks and a crane movable along a runway over said tanks, the improvement wherein said crane comprises hoist support means engaged on said runway for movement along a path of travel above said open tanks, said support means being actuatable through repeated cycles of acceleration, deceleration and stopping during movement along said runway to selected locations over said tanks; load hoist means carried by said support means for movement to said locations; frame means operatively connected to said hoist means and adapted to be raised and lowered by said hoist means when said support means is over a selected tank; an article container rotatably mounted on said frame means so that said container can be placed in and removed from a selected tank by raising and lowering said frame means; and a hydraulic drive system carried on said crane for actuating it through said cycles of acceleration, deceleration and stOpping, said drive system including a rotary fluid motor connected to said support means for powering it along said runway, a rotary fluid motor connected to said hoist means for raising and lowering said container, pump means, circuit means connecting said pump means to said motors, said circuit means defining a closed loop flow path through which fluid is delivered from said pump means to said motors and through which fluid supplied to said motors is returned directly to said pump means without being discharged to a reservoir, and said circuit means including valve means operatively disposed between said pump means and said motors for controlling fluid flow to said motors.

Claim 4

In an arrangement including a plurality of open tanks and a crane movable along a runway over said tanks, the improvement wherein said crane comprises hoist support means engaged on said runway for movement along a path of travel above said open tanks, said support means being actuatable through repeated cycles of acceleration, deceleration and stopping during movement along said runway to selected locations over said tanks; load hoist means carried by said support means for movement to said locations; frame means operatively connected to said hoist means and adapted to be raised and lowered by said hoist means when said support means is over a selected tank; an article container rotatably mounted on said frame means so that said container can be placed in and removed from a selected tank by raising and lowering said frame means; and a hydraulic drive system carried on said crane for actuating it through said cycles of acceleration, deceleration and stOpping, said drive system including a rotary fluid motor connected to said support means for powering it along said runway, a rotary fluid motor connected to said hoist means for raising and lowering said container, pump means, circuit means connecting said pump means to said motors, said circuit means defining a closed loop flow path through which fluid is delivered from said pump means to said motors and through which fluid supplied to said motors is returned directly to said pump means without being discharged to a reservoir, and said circuit means including valve means operatively disposed between said pump means and said motors for controlling fluid flow to said motors.

Claim 5

In an arrangement including a plurality of open tanks and a crane movable along a runway over said tanks, the improvement wherein said crane comprises hoist support means engaged on said runway for movement along a path of travel above said open tanks, said support means being actuatable through repeated cycles of acceleration, deceleration and stopping during movement along said runway to selected locations over said tanks; load hoist means carried by said support means for movement to said locations; frame means operatively connected to said hoist means and adapted to be raised and lowered by said hoist means when said support means is over a selected tank; an article container rotatably mounted on said frame means so that said container can be placed in and removed from a selected tank by raising and lowering said frame means; and a hydraulic drive system carried on said crane for actuating it through said cycles of acceleration, deceleration and stopping, said drive system including a first rotary fluid motor connected to said support means for powering it along said runway, a second rotary fluid motor connected to said hoist means for raising and lowering said container, a hydraulic drive unit including a variable delivery pump and first and second flow passages connected to said pump, and circuit means defining a closed loop fluid flow path connecting said motors in series to said first and second passages, said circuit means being characterized by the absence of a fluid-containing reservoir so that the fluid supplied by said pump to said motors is returned directly to said pump, and said circuit means including first and second directional valves between said pump and said first and second motors.

Claim 6

In an arrangement including a plurality of open tanks and a crane movable along a runway over said tanks, the improvement wherein said crane comprises hoist support means engaged on said runway for movement along a path of travel above said open tanks, said support means being actuatable through repeated cycles of acceleration, deceleration and stopping during movement along said runway to selected locations over said tanks; load hoist means carried by said support means for movement to said locations; frame means operatively connected to said hoist means and adapted to be raised and lowered by said hoist means when said support means is over a selected tank; an article container rotatably mounted on said frame means so that said container can be placed in and removed from a selected tank by raising and lowering said frame means; and a hydraulic drive system carried on said crane for actuating it through said cycles of acceleration, deceleration and stopping, said drive system including a first rotary fluid motor connected to said support means for powering it along said runway, a second rotary fluid motor connected to said hoist means for raising and lowering said container, a hydraulic drive unit including a variable delivery pump and first and second flow passages connected to said pump, and circuit means defining a closed loop fluid flow path connecting said motors in series to said first and second passages, said circuit means being characterized by the absence of a fluid-containing reservoir so that the fluid supplied by said pump to said motors is returned directly to said pump, and said circuit means including first and second directional valves between said pump and said first and second motors.

Claim 7

In an arrangement including a plurality of open tanks and a crane movable along a runway over said tanks, the improvement wherein said crane comprises a hoist support means engaged on said runway for movement along a path of travel above said open tanks, said support means being actuatable through repeated cycles of acceleration, deceleration and stopping during movement along said runway to selected locations over said tanks; load hoist means carried by said support means for movement to said locations; frame means operatively connected to said hoist means and adapted to be raised and lowered by said hoist means when said support means is over a selected tank; an article container rotatably mounted on said frame means so that said container can be placed in and removed from a selected tank by raising and lowering said frame means; and a hydraulic drive system carried on said crane for actuating it through said cycles of acceleration, deceleration and stopping, said drive system including a first rotary fluid motor connected to said support means for powering it along said runway, a second rotary fluid motor connected to said hoist means for raising and lowering said container, a hydraulic drive unit including a variable delivery pump and first and second passages connected to said pump, and circuit means connecting said motors in series to said first and second passages of said drive unit, said circuit means including first and second directional valves, said first valve having first and second ports connected to one of said motors, a third port connected to a first port of said second valve and a Fourth port connected to one of said drive unit passages, and said second valve having second and third ports connected to the other of said motors and a fourth port connected to the other of said drive unit passages, said circuit means defining a closed loop flow path characterized by the absence of a reservoir.

Claim 8

In an arrangement including a plurality of open tanks and a crane movable along a runway over said tanks, the improvement wherein said crane comprises a hoist support means engaged on said runway for movement along a path of travel above said open tanks, said support means being actuatable through repeated cycles of acceleration, deceleration and stopping during movement along said runway to selected locations over said tanks; load hoist means carried by said support means for movement to said locations; frame means operatively connected to said hoist means and adapted to be raised and lowered by said hoist means when said support means is over a selected tank; an article container rotatably mounted on said frame means so that said container can be placed in and removed from a selected tank by raising and lowering said frame means; and a hydraulic drive system carried on said crane for actuating it through said cycles of acceleration, deceleration and stopping, said drive system including a first rotary fluid motor connected to said support means for powering it along said runway, a second rotary fluid motor connected to said hoist means for raising and lowering said container, a hydraulic drive unit including a variable delivery pump and first and second passages connected to said pump, and circuit means connecting said motors in series to said first and second passages of said drive unit, said circuit means including first and second directional valves, said first valve having first and second ports connected to one of said motors, a third port connected to a first port of said second valve and a Fourth port connected to one of said drive unit passages, and said second valve having second and third ports connected to the other of said motors and a fourth port connected to the other of said drive unit passages, said circuit means defining a closed loop flow path characterized by the absence of a reservoir.

Claim 9

Apparatus as claimed in claim 1 wherein said hydraulic circuit means includes valve means for controlling the supply of fluid to said motor means.

Claim 10

Apparatus as claimed in claim 2 wherein said pump means is a variable delivery pump, and including control means connected to said pump for controlling the fluid output and thereby regulating the speed of said motors.

Claim 11

Apparatus as claimed in claim 6 wherein said means connected to said pump includes an external control arm and piston-cylinder means connected to said arm.

Claim 12

Apparatus as claimed in claim 4, wherein said pump includes selectively positionable control means for controlling the output of fluid and thereby regulating the speed of said motors, and including a piston-cylinder means connected to control means for moving said control means to selected positions.

Claim 13

Apparatus as claimed in claim 8 wherein said drive unit includes a second pump, and fluid circuit means connecting said second pump to said piston-cylinder means, said fluid circuit means including directional valve means for controlling operation of said piston-cylinder means.