Excavating – Combined or convertible – Having quick-connect coupling
Reissue Patent
2000-03-16
2001-08-14
Batson, Victor (Department: 3671)
Excavating
Combined or convertible
Having quick-connect coupling
C414S723000
Reissue Patent
active
RE037320
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to tool couplers for excavation, demolition and construction equipment.
Some types of construction equipment, such as backhoes and excavators, have a movable dipperstick (also referred to as an arm) to which a variety of tools, such as, for example, buckets and grapples, can be attached. A hydraulic linkage allows the equipment operator to pivot the tool from the free end of the dipperstick. To simplify the process of changing tool attachments, a universal coupler can be fixed to the dipperstick linkage. A selected tool can then be removably attached to the coupler, a process that typically involves manually positioning at least one latch pin between the coupler and the tool.
There is a trend in the industry to use an actuated coupler on the end of the dipper stick for connecting and disconnecting a tool from the linkage. A great advantage of these systems is that the operator can actuate the coupler to connect or disconnect a tool without the assistance of another worker and without having to leave the cab of the vehicle.
One type of actuated coupler first engages a crossbar formed in the tool with hooks depending from the coupler, and then engages a latch pin (or a block or a wedge) with a mating receptacle formed in a collar on the tool. A double-action hydraulic cylinder in line with the latch pin is positioned so that the cylinder extends to push the latch pin into the receptacle. In disengaging the tool from the coupler, the operator retracts the rod into the cylinder body, pulling the pin out of the receptacle.
SUMMARY OF THE INVENTION
The invention provides a coupling assembly for coupling a tool to a dipperstick, or arm, on an apparatus which has a hydraulic system for moving the tool. The coupling assembly includes a coupler body having a frame that defines a central cavity, and also having link structure for pivotally coupling to the dipperstick. An actuator assembly positioned within the central cavity includes a latch pin movable between an extended position and a retracted position. In the extended position, an end of the latch pin projects rearward from an opening in a rear end of the frame for engaging an aperture or receptacle defined by the tool. In the retracted position, the end of the latch pin is disengaged from the tool receptacle and positioned substantially within the frame. The actuator assembly also includes a hydraulic latch cylinder that has a movable part, and a fixed part. The movable part is coupled to the latch pin by a latch pin coupling assembly, which is structured and arranged such that, when the movable part is extended from the fixed part, the latch pin moves to the retracted position.
According to another aspect of the invention, the latch pin coupling assembly includes a bias member structured and arranged to apply a bias force that urges the latch pin toward the extended position. When a threshold level of hydraulic pressure is applied to the latch cylinder, the movable part of the cylinder overcomes the bias force and extends to move the latch pin to the retracted position and out of engagement with the tool.
Another feature of the invention is that the latch cylinder can be a single-action cylinder.
According to another feature of the invention, the latch cylinder can be positioned on an axis different from an axis defined by the latch pin, such as along side the latch pin. This feature provides a compact arrangement. The system is easily adaptable to any type of quick coupler type system due to the compactness and placement of the actuating cylinder.
According to another feature of the invention, the hydraulic pressure to the latch cylinder can be controlled by an electrically actuated valve assembly that hydraulically couples the dipperstick hydraulics to the latch cylinder. The valve assembly can include one or more solenoid valves that only allow hydraulic pressure to enter and remain in the latch cylinder when they are energized.
According to another feature of the invention, the valve assembly can be structured and arranged such that the dipperstick hydraulics must be approximately fully pressurized while extended to pressurize the latch cylinder.
According to another feature of the invention, the coupling assembly can also include a pin indicator that readily shows whether the latch pin retracted. The indicator is located such that it can be viewed easily from the operator position.
According to another feature of the invention, a drop in hydraulic pressure in the latch cylinder below the threshold level allows the bias spring to push the coupling pin towards the extended position. As unexpected hydraulic pressure loss can be caused by a failure in the hydraulic system or by a failure in the valve assembly. The spring apply, hydraulic release system is safe in that it assures that an attached tool will not accidentally uncouple from the coupling assembly if there is a loss in hydraulic pressure in the latch cylinder.
The invention also provides a method of removing a tool from the coupler assembly having features as described above. An operator can remove a tool by the steps of applying hydraulic pressure to a latch cylinder that has a part fixed relative to the coupler body and a movable part rigidly coupled to the latch pin, extending the movable part from the fixed part, thereby urging the latch pin to the retracted position, engaging a cross member of the excavation tool with a hook structure depending and extending forward from the coupler body, rotating the coupler body toward the tool, aligning the latch pin with a mating receptacle formed in the excavation tool, reducing hydraulic pressure to the latch cylinder, and applying a bias force to the latch pin, urging the latch pin to the engaged position, thereby engaging the latch pin in the receptacle and securing the excavation tool to the coupler body.
According to another aspect of the invention, the method further includes the step of removing the tool from the coupler, including rotating the coupler body and the tool to a full forward position, again applying hydraulic pressure to the latch cylinder, again extending the movable part from the fixed part, thereby urging the latch pin to the retracted position and disengaging the latch pin from the receptacle, and disengaging the hook structure from the cross member of the excavation tool.
The latch cylinder extends using the more powerful head end to extract the latch pin, whereas coupling systems using an in-line dual-action cylinder and latch pin arrangement use the less powerful rod end for this purpose. This feature of the invention is important when extracting a frozen pin, which can require substantially more force than inserting a free moving pin.
Since the hydraulic system uses a single-action latch cylinder, it only requires one hydraulic line between the valve assembly and the latch cylinder. This is simple and inexpensive compared with coupling systems that use a dual-action cylinder, and that require two hydraulic connections.
The rod of the latch cylinder is normally in the retracted position during the tool working period. Because the latch cylinder is retracted, the rod of the latch cylinder is not subject to damage from rocks and sharp objects. Normally, the only time the rod is extended, and thereby exposed to the elements and contaminants, is when a tool is being attached or detached from the coupling assembly.
A feature of the invention is that if there is a loss of either electrical or hydraulic power, the latch pin will extend or “insert” automatically. If electrical power inadvertently gets to the solenoid valves, the tool has to be fully rolled forward and inward in order for the pressure to build up in the latch cylinder to retract latch pin. In this position, the coupler hooks are fully engaged and the likelihood of the tool falling off is minimized. One cannot simply throw the switch and have the tool fall to the ground.
REFERENCES:
patent: 2984985 (1961-05-01), MacMillin
patent: 3231116 (1966-01-01), Powell
patent: 3269570 (1966-08-01), Wal
Batson Victor
Fish & Richardson P.C.
WEC Co.
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