Hydraulically operated clam-shell device

• US 4,702,076 A
• Filed: 07/23/1984
• Issued: 10/27/1987
• Est. Priority Date: 01/13/1984
• Status: Expired due to Fees

• Current Assignee: Dynamic Hydraulic Systems Incorporated
• Original Assignee: Dynamic Hydraulic Systems Incorporated
• Inventors: Rosman, Alan H.
• Primary Examiner(s): Look, Edward K.
• Application Number:
  US06/633,397
• Time in Patent Office: 1,191 Days
• Field of Search: 60/413, 60/414, 60/415, 60/416, 60/417, 60/418, 60/487, 60/488, 60/490, 60/911, 60/372, 60/378, 37/116, 37/DIG. 1, 37/DIG. 7, 37/DIG. 9, 37/DIG. 11, 37/183 R, 37/184, 37/136, 414/730, 414/726, 91/512, 91/517, 91/189 R, 212/259, 212/251, 212/250, 294/68.23, 294/111, 417/217
• US Class Current: 60/372
• CPC Class Codes: B66D 1/08 incorporating fluid motors
• CPC Class Codes: B66F 9/22 Hydraulic devices or systems
• CPC Class Codes: F15B 21/14 Energy-recuperation means

Abstract

The invention contemplates a hydraulically operated twin-cable suspension for a clamshell or the like load-handling device. In a preferred embodiment, a charged accumulator is effectively a counterweight and is the source of all hydraulic fluid needed for the full range of actuation of two traction cylinders, one for each of the respective cables. Both cables automatically share the load, without slack, in any elevational situation, and simple hydraulic control circuitry selectively enables (a) an automated closing dig into loadable material and (b) a quick opening for load discharge. A single power integrator is interposed between the accumulator and the two traction cylinders for directionally controlling hydraulic-fluid displacement between the accumulator and the traction cylinders, as needed for all cable displacements.

Claims

1. In a cable-suspended hydraulically operated lift system wherein a clamshell or the like device having separate hook-cable and clamshell-cable suspension connections is to be lifted and/or actuated by separate cables respectively coupled to said hook-cable and clamshell-cable connections, the improvement wherein first and second traction cylinders are mounted in parallel for independent traction-actuation of the respective cables, pressurized hydraulic-accumulator means connected as a closed system which includes separate connections to said traction cylinders, said closed system including reversibly controllable rotary power-integrator means between said accumulator means and the respective separate connections to said traction cylinders, valve means in the separate connection to the traction cylinder associated with the hook-cable connection, said valve means having a first position providing an open-flow connection between said accumulator means and said hook-cable traction cylinder and a second position blocking flow therebetween, and means including a pressure-responsive threshold device connected for response to pressure in the connection to said clamshell-cable traction cylinder, said last-mentioned means being so associated with said valve means as to determine a shift from the second to the first positions thereof upon achievement of a predetermined sensed threshold pressure so that flow from said power-integrator means causes both cylinders to share the lifting load.

2. The improvement of claim 1, in which the separate connection to the traction cylinder associated with the clamshell cable includes further valve means having a first position providing an open-flow connection between the accumulator means and the clamshell-cable traction cylinder and a second position blocking flow therebetween while also venting pressure fluid from the clamshell-cable traction cylinder, and means including a pump for returning vented pressure fluid to said accumulator means.

3. The improvement of claim 2, in which said further valve means includes means normally urging the same to said first position, and selectively operable control means for actuating said further valve means to the second position thereof.

4. The improvement of claim 3, in which said further valve means is solenoid-operated, said control means including a push-button operated circuit connection to the solenoid of said valve means.

5. The improvement of claim 2, in which a vent line connected to said further valve means includes a throttling orifice, thereby limiting the rate of clamshell opening.

6. The improvement of claim 1, in which said valve means in said second position additionally vents pressure fluid from said hook-cable traction cylinder, and means including a pump for returning vented pressure fluid to said accumulator means.

7. The improvement of claim 6, in which a vent line connected to said valve means includes a throttling orifice, thereby limiting the rate of clamshell closure.

8. The improvement of claim 1, in which said power-integrator means includes a rotor adapted for connection to a prime mover.

9. The improvement of claim 8, in which the prime mover is a reversible electric motor.

10. The improvement of claim 8, in which the prime mover is a single direction electric motor, and means for reversibly selecting the direction of flow through said integrator means.

11. The improvement of claim 8, in which the prime mover is a diesel engine, and means for reversibly selecting the direction of flow through said integrator means.

12. The improvement of claim 1, in which said valve means includes means normally urging the same to said first position, and selectively operable control means for actuating said valve means to said second position.

13. The improvement of claim 12, in which said valve means is solenoid-operated, said control means including a push button and relay with hold-in contacts for retaining a solenoid operation of said valve means, said pressure-responsive threshold device including means for tripping out a hold-in function of said relay.

14. In a cable-suspended hydraulically operated lift system wherein a clamshell or the like device having separate hook-cable and clamshell-cable suspension connections is to be lifted and/or actuated by separate cables respectively coupled to said hook-cable and clamshell-cable connections, the improvement wherein first and second hydraulic-lift actuators are mounted in parallel for independent actuation of the respective cables, pressurized hydraulic-accumulator means connected as a closed system which includes separate connections to said actuators, said closed system including reversibly controllable rotary power-integrator means between said accumulator means and the respective separate connections to said traction cylinders, valve means in the separate connection to the actuator associated with the hook-cable connection, said valve means having a first position providing an open-flow connection between said accumulator means and said hook-cable actuator and a second position blocking flow therebetween, and means including a pressure-responsive threshold device connected for response to pressure in the connection to said clamshell-cable actuator, said last-mentioned means being so associated with said valve means as to determine a shift from the second to the first positions thereof upon achievement of a predetermined sensed threshold pressure so that flow from said power-integrator means causes both cylinders to share the lifting load.

17. The improvement of claim 14 or claim 15, in which a first pilot-operated check valve is interposed between said accumulator means and said integrator means and a second pilot-operated check valve is interposed between said accumulator means and said actuators and with parallel connection to the respective hydraulic-lift actuators, said check valves being oriented to check flow from said accumulator means to said integrator means and to check flow from said actuators to said integrator means, and pilot-actuating means responsive to rotation of said power-integrator means.

15. In a cable-suspended hydraulically operated lift system wherein a clamshell or the like device having separate hook-cable and clamshell-cable suspension connections is to be lifted and/or actuated by separate cables respectively coupld to said hook-cable and clamshell-cable connections, the improvement wherein first and second hydraulic-lift actuators are mounted in parallel for independent actuation of the respective cables, pressurized hydraulic-accumulator means connected as a closed system which includes separate connections to said actuators, said closed system including reversibly controllable rotary power-integrator means between said accumulator means and the respective separate connections to said traction cylinders, valve means in the separate connection to the actuator associated with the hook-cable connection, said valve means having a first position providing an open-flow connection between said accumulator means and said hook-cable actuator and a second position blocking flow therebetween while venting pressure fluid in said hook-cable actuator, and means including a pressure-responsive threshold device connected for response to pressure in the connection to said clamshell-cable actuator, said last-mentioned means being so associated with said valve means as to determine a shift from the second to the first positions thereof upon achievement of a predetermined sensed threshold pressure so that flow from said power-integrator means causes both cylinders to share the lifting load, and means including a pump for returning vented pressure fluid to said acumulator means.

16. The improvement of claim 15, and including selectively operable further valve means in the separate connection to the clamshell-cable actuator, said further valve means having a normal position providing an open-flow connection between the accumulator means and said clamshell-cable actuator and a selectively operable position (a) blocking the open-flow connection and (b) venting pressure fluid from said clamshell-cable actuator.