Claims
- 1. A fluid-powered, rotary dipper stick assembly, usable with a vehicle having a boom arm and a selectively operable dipper stick actuator associated therewith for pivotal movement of the dipper stick assembly through a boom plane containing the boom arm, the dipper stick assembly being usable with a work implement such as a bucket having a selectively operable work implement actuator associated therewith for pivotal movement of the work implement through a dipper stick plane containing the dipper stick assembly, the dipper stick assembly comprising:
- a boom attachment head having a first attachment portion attachable to the vehicle boom arm, and a second attachment portion attachable to the dipper stick actuator to provide pivotal movement of said boom attachment head through the boom plane upon actuation of the dipper stick actuator, said first attachment portion and said second attachment portion being selectively detachable from the boom arm and the dipper stick actuator;
- a work implement attachment head having a third attachment portion attachable to the work implement to provide pivotal movement of the work implement through the dipper stick plane upon actuation of the work implement actuator, said third attachment portion being selectively detachable from the work implement;
- an elongated, generally cylindrical inner body having a longitudinal axis and generally extending at least partially between said boom attachment head and said work implement attachment head, with a first inner body end toward said boom attachment head and a second inner body end toward said work implement attachment head;
- a shaft extending longitudinally with in said inner body in general coaxial arrangement with said inner body, said inner body being rigidly attached to said boom attachment head, and said shaft being rigidly attached to said work implement attachment head, said inner body and said shaft being selectively rotatable relative to each other about said body longitudinal axis;
- an elongated, generally cylindrical outer body generally extending longitudinally between said boom attachment head and said work implement attachment head in generally coaxial arrangement with said inner body, with a first outer body end toward said boom attachment head and a second outer body end toward said work implement attachment head, said outer body having a fourth attachment portion spaced away from said work implement attachment head and attachable to the work implement actuator to apply a counterforce upon actuation of the work implement actuator to rotate the work implement in the dipper stick plane, said inner body being disposed within said outer body with an outward wall portion thereof positioned immediately adjacent to an inward wall portion of said outer body, said inner body extending from said first inner body end positioned toward said first outer body end to said second inner body end positioned toward a midportion of said outer body between said first and second outer body ends, said outer body being rigidly attached to said shaft toward said second outer body end, said outer body and said shaft being selectively rotatable as a unit relative to said inner body about said body longitudinal axis, and the assembly further includes first radial bearings disposed between said inward wall portion of said outer body and said outward wall portion of said inner body toward said first inner body end and second radial bearings disposed between said inward wall portion of said outer body and said outward wall portion of said inner body toward said second inner body end, said first and second inner body ends being spaced apart by a sufficient distance to provide increased stability against forces generated during use of the dipper stick assembly tending to move said outer body out of coaxial alignment with said shaft; and
- linear-to-rotary transmission means disposed within said outer body and operable for producing rotational movement of said shaft relative to said inner body, said transmission means including a piston for the selective application of fluid pressure to one or an other side thereof to produce linear movement of said piston within said outer body selectively toward said first and second outer body ends, and means for translating linear movement of said piston toward one of said first or second outer body ends into clockwise relative rotational movement between said shaft and said inner body and translating linear movement of said piston toward the other of said first or second outer body ends into counterclockwise relative rotational movement between said shaft and said inner body to selectively rotate said work implement attachment head and hence the work implement about said body longitudinal axis independent of said boom attachment head and hence the boom arm, whereby the dipper stick assembly is capable of handling significantly increased loads without interfering with the operation of said linear-to-rotary transmission means such as can occur on misalignment. interfering with the operation of said linear-to-rotary transmission means ,such as can occur on misalignment.
- 2. The rotary dipper stick assembly of claim 1 wherein said piston is positioned for reciprocal movement within said outer body and the dipper stick assembly includes an outer seal positioned to seal between said piston and an inward wall portion of said outer body and defines a fluid-tight compartment at least partially within said outer body to each side of said piston.
- 3. The rotary dipper stick assembly of claim 2 wherein said piston is an annular piston having a central aperture through which said shaft extends, and the dipper stick assembly further includes an inner seal positioned to seal between said piston and an outward smooth wall portion of said shaft and define said fluid-tight compartments.
- 4. The rotary dipper stick assembly of claim 1 wherein said shaft extends between said boom attachment head and said work implement attachment head, and retains said boom attachment head and said work implement head against separation along said body longitudinal axis.
- 5. The rotary dipper stick assembly of claim 1 wherein said shaft extends between said boom attachment head and said work implement attachment head, and wherein said outer body and said shaft are rigidly attached to said work implement attachment head and rotate as a unit with said work implement attachment head through the dipper stick plane upon actuation of the work implement actuator, and said inner body is rigidly attached to said boom attachment head and rotates with said boom attachment head through the boom plane upon actuation of the dipper stick actuator, said shaft applying rotational drive to said work implement attachment head for selective rotation thereof in clockwise and counterclockwise directions about said body longitudinal axis independent of said boom attachment head upon selective application of fluid pressure to one or another side of said piston.
- 6. The rotary dipper stick assembly of claim 1 wherein said fourth attachment portion is rigidly attached to an outward wall portion of said outer body toward said first outer body end and attachable to the work implement actuator.
- 7. The rotary dipper stick assembly of claim 1 wherein said inner body is rigidly attached to said boom attachment head, and wherein said shaft further includes an end cap attached thereto at a longitudinally outward side of said inner body at said first inner body end and sized with a diameter larger than said inner body, and the dipper stick assembly further includes bearing means for rotatably supporting said end cap at said first inner body end against longitudinal movement toward said second inner body end, said end cap retaining said work implement attachment head against separation from said boom attachment head along said body longitudinal axis while permitting free rotation of said shaft relative to said boom attachment head.
- 8. The rotary dipper stick assembly of claim 7 wherein said end cap is threadably received on a correspondingly threaded end portion of said shaft extending to said longitudinally outward side of said first inner body end, said end cap being selectively longitudinally adjustable on said shaft threaded end portion to adjust the longitudinal force said end cap applies on said inner body toward said second body end to retain said work implement attachment head against separation from said boom attachment head.
- 9. The rotary dipper stick assembly of claim 1 wherein said linear-to-rotary transmission means includes a splined inward surface portion of said inner body toward said second inner body end, and further includes a sleeve having a correspondingly splined outward surface portion meshing with said inner body splined inward surface portion, said sleeve being in operative engagement with said piston for movement therewith.
- 10. The rotary dipper stick assembly of claim 9 wherein said inner body splined inward surface portion and said sleeve splined outward surface portion having meshing helical splines.
- 11. The rotary dipper stick assembly of claim 9 wherein said sleeve has a central aperture through which said shaft extends, said sleeve having a splined inward surface portion and said shaft having a correspondingly splined outward surface portion meshing with said sleeve splined inward surface portion.
- 12. The rotary dipper stick assembly of claim 11 wherein said sleeve splined inward surface portion and said shaft splined outward surface portion have meshing helical splines.
- 13. The rotary dipper stick assembly of claim 1 wherein said boom attachment head has a connector portion to which one of said body or said shaft is rigidly attached, said connector portion being spaced sufficiently apart from said first attachment portion to allow said fourth attachment portion to avoid hitting the boom arm upon operation of said linear-to-rotary transmission means to produce rotational movement of said shaft relative to said body, whereby full 360.degree. or greater rotation of the work implement is permitted about the body longitudinal axis, without said fourth attachment portion and the work implement actuator attached thereto contacting the boom arm.
- 14. A fluid-powered, rotary dipper stick assembly, usable with a vehicle having a boom arm and a selectively operable dipper stick actuator associated therewith for pivotal movement of the dipper stick assembly through a boom plane containing a boom arm, the dipper stick assembly being usable with a work implement such as a bucket having a selectively operable work implement actuator associated therewith for pivotal movement of the work implement through a dipper stick plane containing the dipper stick assembly, the dipper stick assembly comprising:
- a boom attachment head having a first attachment portion attachable to the vehicle boom arm, and a second attachment portion attachable to the dipper stick actuator to provide pivotal movement of said boom attachment head through the boom plane upon actuation of the dipper stick actuator;
- a work implement attachment head having a third attachment portion attachable to the work implement to provide pivotal movement of the work implement through the dipper stick plane upon actuation of the work implement actuator;
- an elongated, generally cylindrical outer body having a longitudinal axis and generally extending substantially fully between said boom attachment head and said work implement attachment head, with a first outer body end toward said boom attachment head and a second outer body end toward said work implement attachment head, said outer body having a fourth attachment portion rigidly attached to an outward wall portion of said outer body toward said first outer body end spaced away from said work implement attachment head and attachable to the work implement actuator to apply a counterforce upon actuation of the work implement actuator to rotate the work implement in the dipper stick plane;
- a shaft extending longitudinally within said body in general coaxial arrangement with said body, said shaft and said outer body being rigidly attached together toward said second outer body end and said shaft being rigidly attached to said work implement attachment head and applying rotational driver thereto;
- an elongated, generally cylindrical inner body disposed within said outer body with an outward wall portion thereof positioned immediately adjacent to an inward wall portion of said outer body, said inner body having first and second inner body ends and extending longitudinally within said outer body in generally coaxial arrangement therewith from said first inner body end positioned toward said first outer body end to said second inner body end positioned toward a midportion of said outer body between said first and second outer body ends, said first and second inner body ends being spaced apart by a sufficient distance to provide increased stability against forces generated during use of the dipper stick assembly tending to move said outer body out of coaxial alignment with said shaft, said inner body being rigidly attached to said boom attachment head toward said first inner body end, said shaft and outer body being selectively rotatable as a unit relative to said inner body about said body longitudinal axis; and
- linear-to-rotary transmission means disposed within said outer and inner bodies and operable for producing rotational movement of said shaft and outer body relative to said inner body, said transmission means including a piston for the selective application of fluid pressure to one or another side thereof to produce linear movement of said piston within one of said inner or outer bodies selectively toward said first and second outer body ends, and means for translating linear movement of said piston toward one of said first or second outer body ends into clockwise relative rotational movement between said shaft and outer body and said inner body, and translating linear movement of said piston toward the other of said first or second outer body ends into counterclockwise relative rotational movement between said shaft and outer body and said inner body to selectively rotate said work implement attachment head and hence the work implement about said body longitudinal axis independent of said boom attachment head and hence the boom arm.
- 15. The rotary dipper stick assembly of claim 14, further including a first radial bearing disposed between said inward wall portion of said cuter body and said outward wall portion of said inner body toward said first inner body end, and a second radial bearing disposed between said inward wall portion of said outer body and said outward wall portion of said inner body toward said second inner body end.
- 16. The rotary dipper stick assembly of claim 14 wherein said piston is positioned for reciprocal movement within said outer body and the dipper stick assembly includes an outer seal positioned to seal between said piston and an inward wall portion of said outer body and defines a fluid-tight compartment within said outer body to each side of said piston.
- 17. The rotary dipper stick assembly of claim 14 wherein said shaft extends between said boom attachment head and said work implement attachment head, and retains said boom attachment head and said work implement head against separation along said body longitudinal axis.
- 18. The rotary dipper stick assembly of claim 17 wherein said boom attachment head includes a support portion rigidly attached thereto, and wherein said shaft further includes retaining means for engaging said support portion and retaining said work implement attachment head against separation from said boom attachment head along said body longitudinal axis while permitting free rotation of said work implement attachment head relative to said shaft.
- 19. The rotary dipper stick assembly of claim 18 wherein said retaining means is further selectively adjustable to adjust the longitudinal force said shaft applies on said support portion in a direction toward said second body end to retain said work implement attachment head against separation from said boom attachment head.
DISCLOSURE OF THE INVENTION
This application is a division of U.S. Pat. application Ser. No. 07/337,749, filed Apr. 13, 1989.
1. Technical Field
The present invention relates generally to the boom arms or, as they are generally known in the trade, "dipper sticks," which carry a bucket or other work implement used by backhoes and excavators, and more particularly, to a dipper stick which is selectively rotatable about its longitudinal axis.
2. Background of the Invention
Backhoes, excavators and similar types of vehicles have an articulated arm assembly with a boom arm pivotally connected to the vehicle and a dipper stick pivotally attached to the boom arm at an end remote from the vehicle. The arm assembly usually has a bucket pivotally attached at the free end of the dipper stick. Generally, the articulated arm assembly is pivotally connected to the vehicle so that the arm assembly can be rotated about a vertical axis relative to the vehicle, or is attached to a cab with the cab and arm assembly being rotatable as a unit about a vertical axis relative to the vehicle undercarriage. The bucket is pivotally attached to the dipper stick by a clevis which serves as a pivot point for the bucket relative to the dipper stick. The bucket is rotatable about the dipper stick pivot point in a generally vertical plane containing the boom arm and the dipper stick. While the entire articulated arm assembly can be rotated relative to the vehicle, the dipper stick and attached bucket could not be rotated about the longitudinal axis of the dipper stick. Thus, the dipper stick and attached bucket could not be rotated independent of the boom arm.
There are occasions, however, when it would be very desirable to be able to rotate the dipper stick and hence the bucket independent of the boom arm so that the bucket can work along a cut line out of the plane containing the boom arm and the dipper stick. This would allow an operator to dig an offset ditch, such as a ditch running along a straight cut line at a distance to the side of the vehicle, without moving the vehicle. Of course, when digging such a ditch it is desirable to keep the bucket in alignment with the cut line at all times to provide a ditch having the precise width of the bucket being used. Without being able to rotate the dipper stick about its longitudinal axis, in the past, this meant aligning the vehicle so that the plane containing the boom arm and the dipper stick was in coincidence with the cut line. It was not possible to park the vehicle off to the side of the ditch and spaced away from the cut line, such as is sometimes desirable, and dig a narrow ditch along the cut line.
Being able to rotate the dipper stick also would allow the operator much greater flexibility in the cut being made by the bucket in other situations and minimize the number of vehicle moves necessary to accomplish the cut desired. One example is the digging of a box hole with a square corner where the bucket must dig from two directions at right angles to each other to make a clean corner cut. Another example is digging around piles and other obstacles, or digging several ditches at different angles, such as a main and branch water supply or drainage ditches. It is very desirable to be able to complete such cuts without moving the vehicle. Being able to rotate the dipper stick enables the operator to perform such digging jobs with little or no movement of the vehicle, and also to lift or manipulate objects, such as rocks or slabs from all angles without moving the vehicle. The ability to rotate the dipper stick allows the operator to conveniently perform additional jobs, such as rotating the dipper stick in one direction to pick up material, and then rotating the dipper stick by 180.degree. or as desired and extend the articulated arm to deliver the material to another place.
The increased versatility noted above has been realized with the advent of the rotatable dipper stick. In the past, such rotatable dipper stick units have utilized a dipper stick with a boom attachment head comprising a large turntable bearing with a ring gear machined into the perimeter of the rotatable turntable bearing member. A hydraulic motor with a pinion gear in engagement with the turntable gear provided the rotational drive. A brake was used to stop the rotational movement when desired and to hold the rotational position of the turntable bearing member while the dipper stick was being used to dig. This arrangement is bulky, heavy and lacks precision control both during rotation o the dipper stick and when being held in position while work is being performed. The resulting dipper stick assembly is much larger than a conventional non-rotatable dipper stick and larger than desirable for all but the largest excavation vehicles. Further, such a design arrangement cannot be reduced in size for use in the smaller sized dipper sticks necessary for smaller-sized backhoes and excavators. While such rotatable dipper sticks have existed for several years, the drive mechanisms used have not provided optimum results.
It will therefore be appreciated that there has been a significant need for a rotatable dipper stick rotated by a mechanism able to transmit a large torque to the dipper stick and firmly hold the dipper stick in the desired rotational position even under large work loads. Preferably, the rotatable dipper stick should be rotatable through more than 360.degree.. The rotatable dipper stick should be smaller and lighter than those presently available, and fit within the normal dimensional envelope of presently existing conventional nonrotatable dipper sticks. The rotatable dipper stick should also be effectively and economically manufacturable in small as well as large sizes. Moreover, the rotatable dipper stick should have a precision rotational drive mechanism capable of precise positional control and able to hold its rotational position without the use of a separate brake mechanism which can slip or fail. The rotatable dipper stick should also be able to operate without failure when subjected to large side loads. The present invention fulfills these needs and further provides other related advantages.
The present invention resides in a vehicle having a fluid-powered, rotary dipper stick assembly mounted to a boom arm of the vehicle. The vehicle includes a selectively operable dipper stick actuator associated with the boom arm for rotation of the dipper stick assembly through a boom plane containing the boom arm.
The dipper stick assembly has a work implement, such as a bucket, and a selectively operable work implement actuator associated therewith for pivotal movement of the work implement through a dipper stick plane containing the dipper stick assembly. It is note that the invention may also be practiced by the manufacture of a dipper stick assembly not including the vehicle, boom arm or dipper stick actuator. Similarly, the invention may be practiced by the manufacture of the dipper stick assembly without the work implement attached thereto. The particular form the invention takes depends upon whether a backhoe, excavator or other type of vehicle using the dipper stick assembly is being sold as original equipment or whether the dipper stick assembly is being sold as a retrofit product for existing vehicles.
The dipper stick assembly of the present invention includes a boom attachment head having a first attachment portion attachable to the vehicle boom arm, and a second attachment portion attachable to the dipper stick actuator to provide pivotal movement of the boom attachment head through the boom plane upon actuation of the dipper stick actuator. In a preferred embodiment of the invention, the first and second attachment portions are selectively detachable from the boom arm and the dipper stick actuator.
The dipper stick assembly further includes a work implement attachment head having a third attachment portion attachable to the work implement to provide pivotal movement of the work implement through the dipper stick plane upon actuation of the work implement actuator. Preferably, the third attachment portion is selectively detachable from the work implement.
An elongated, generally cylindrical body having a longitudinal axis extends at least partially between the boom attachment head and the implement attachment head. The body has a first body end toward the boom attachment head and a second body end toward the work implement attachment head.
A shaft extends longitudinally within the body in general coaxial arrangement with the body. One of the body or the shaft is rigidly attached to the boom attachment head, and the other of the body or shaft is rigidly attached to the work implement attachment head and has a fourth attachment portion spaced away from the work implement attachment head. The fourth attachment portion is attachable to the work implement actuator to supply a counterforce upon actuation of the work implement actuator to rotate the work implement in the dipper stick plane. The body and shaft are selectively rotatable relative to each other about the body longitudinal axis.
The dipper stick assembly further includes linear-to-rotary transmission means disposed within the body and operable for producing relative rotational movement between the shaft and the body. The transmission means includes a piston for the selective application of fluid pressure to one or an other side thereof to produce linear movement of the piston within the body selectively toward the first and second body ends. Means are provided for translating linear movement of the piston toward one of the first or second body ends into clockwise relative rotational movement between the shaft and the body, and translating linear movement of the piston toward the other of the first or second body ends into counterclockwise relative rotational movement between the shaft and the body to selectively rotate the work implement attachment head and hence the work implement about the body longitudinal axis independent of the boom attachment head and hence the boom arm.
In a preferred embodiment of the invention, the body is an outer body, and the assembly includes an elongated, generally cylindrical inner body disposed within the outer body. The inner body has an outward wall portion thereof positioned immediately adjacent to an inward wall portion of the outer body. The inner body further has first and second inner body ends and extends longitudinally within the outer body in generally coaxial arrangement therewith from the first inner body end positioned toward the first outer body end to the second inner body end positioned toward a midportion of the outer body end between the first and second outer body ends. The inner body is in supporting sliding engagement toward both the first and second inner body ends with the inner wall portion of the outer body.
In one embodiment, the inner body is rigidly attached to the shaft toward the inner body end, and the outer body is selectively rotatable relative to the inner body and the shaft about the body longitudinal axis. The assembly further includes a first radial bearing disposed between the inward wall portion of the outer body and the outer wall portion of the inner body toward the first inner body end. Also included is a second radial bearing disposed between the inward wall portion of the outer body and the outward wall portion of the inner body toward the second inner body end. The first and second inner body ends are spaced apart by a sufficient distance to provide increased stability against forces generated during use of the dipper stick assembly tending to move the outer body out of coaxial alignment with the shaft. As such, the dipper stick assembly is capable of handling significantly increased loads without interfering with the operation of the linear-to-rotary transmission such as can occur on misalignment of the outer body and the shaft.
In one embodiment of the invention, the shaft extends between the boom attachment head and the work implement attachment head, and retains them against separation along the body longitudinal axis. The work implement attachment head includes an annular support bracket rigidly attached thereto and having a central aperture through which the shaft extends. The shaft further includes an end cap attached thereto at a longitudinally outward side of the support bracket and sized with a diameter larger than the support bracket central aperture. Thrust and radial bearings are positioned between the end cap and the support bracket so that the end cap retains the work implement attachment head against separation from the boom attachment head while permitting free rotation of the work implement attachment head relative to the shaft. The end cap is threadably received on a threaded end portion of the shaft to provide selective longitudinal adjustability.
In this embodiment of the invention, the linear-to-rotary transmission means includes a ring gear rigidly attached to the outer body and having splines meshing with splines formed on an outward surface portion of a sleeve. Splines formed on an inward surface of the sleeve mesh with splines formed on an outward surface portion of the shaft. The sleeve is in operative engagement with the piston for movement therewith.
In a second embodiment of the invention, the dipper stick assembly includes a tie rod extending longitudinally within the body in generally coaxial arrangement with the shaft and through a central longitudinally extending aperture in the shaft. The tie rod extends fully between the boom attachment head and the work implement attachment head and retains them against separation along the body longitudinal axis. In this embodiment, the shaft extends from the boom attachment head to about the midportion of the outer body.
In a third embodiment of the invention, the body is an inner body, and the dipper stick assembly further includes an elongated, generally cylindrical outer body generally extending longitudinally between the boom attachment head and the work attachment head in generally coaxial arrangement with the inner body. The outer body has a first outer body end toward the boom attachment head and a second outer body end toward the work implement attachment head. The outer body is rigidly attached to the shaft toward the second outer body end, and the outer body and shaft are selectively rotatable as a unit relative to the inner body about the body longitudinal axis.
In all embodiments of the invention, the boom attachment head has a connector portion to which one of the body or the shaft is rigidly attached. The connector portion is spaced sufficiently apart from the first attachment portion to which the boom arm is attached to allow the fourth attachment portion to avoid hitting the boom arm upon operation of the linear-to-rotary transmission means to produce rotational movement of the shaft relative to the body. With this arrangement, full 360.degree. or greater rotation of the work implement is permitted about the body longitudinal axis, without the fourth attachment portion and the work implement actuator attached thereto contacting the boom arm.
Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.
US Referenced Citations (5)
Non-Patent Literature Citations (1)
| Entry |
| Komatsu Brochure--PF55L All-Around Excavator--4-page brochure. |
Divisions (1)
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Number |
Date |
Country |
| Parent |
337749 |
Apr 1989 |
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Patent Grant
4952116
