Progressive linkage for excavator thumb

An improved dipper stick, tool, and thumb combination includes a progressive linkage for connecting the thumb to a thumb actuator wherein the pivot axis of the thumb idler link connection is spaced from the pivot axis of the tool idler link connection. The pivot axis of the thumb idler link connection may be offset outwardly from the inner surface of the dipper stick. A mounting plate may be connected to the inner surface of the dipper stick to locate the pivot axis in the offset position.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention generally relates to the linkage used to control a thumb used with a bucket on a prime mover such as an excavator. More particularly, the invention relates to a unique mounting and operating configuration for the progressive linkage of the thumb affixed to the dipper stick. Specifically, the present invention relates a thumb progressive linkage that is mounted to a dipper stick independent of the pin and linkage assembly used to control an attachment on the end of the dipper stick.

2. Background Information

An excavator is a machine that generally includes a boom that supports an extendable arm, known in the trade as a “dipper arm,” a “dipper stick,” or a “stick” onto which is attached an excavator tool—such as an excavator bucket or rake. The excavator tool is typically attached to the distal end of the dipper stick with a pivot pin. A piston cylinder assembly operating through a tool linkage assembly is used to control the excavator tool.

An excavator thumb may be used in combination with any of a variety of excavator tools. Pin on types of excavator thumbs typically connected to the distal end of the dipper stick with a pivot pin that also serves to mount the excavator tool. The pin on excavator thumb may be mounted in three control configurations including a stiff arm configuration, a direct connect configuration, and a progressive linkage configuration. The progressive linkage configuration provides a wider range of motion to the thumb than the other control configurations. The progressive linkage control configuration also locates the end of the cylinder rod away from the thumb and bucket by connecting the end of the cylinder rod to a progressive linkage that is, in turn, connected to the thumb body thus protecting the end of the cylinder rod from potential damage.

Numerous stick and bucket configurations are manufactured and sold by a wide variety of manufacturers. Each thumb linkage must be carefully designed for the specific stick linkage and bucket combination. Once a thumb linkage is designed for a specific stick, linkage, and bucket combination, the thumb linkage will not fit essentially any other stick linkage and bucket configuration. The uniqueness of the linkage design prevents the thumb linkages from being interchanged with other machines and thus increases the cost of owning a thumb with a progressive linkage. Excavator owners usually must purchase and maintain a thumb linkage for each of their machines. Another problem with existing progressive linkages is that they often of limited use when installed on short sticks (those of less than nine feet in length) because there is not sufficient room for the piston cylinder actuator. Although a shorter piston cylinder actuator may be used, the range of motion becomes limited. The industry thus desires a progressive linkage configuration that may be readily fit to a variety of bucket and stick configurations, is easy to install, has a greater range of motion, and lowers owning and operating costs.

Another problem with existing progressive thumb linkages is the installation sequence. The process includes repeated trial and error steps that can consume twelve to sixteen hours. The linkage configuration and the mounting sequence should be simple while improving the range of motion for the thumb. The method of mounting the linkage to the dipper stick and connecting the linkage to the thumb should be easy to understand and minimize the time required to install the tool to the excavator.

SUMMARY OF THE INVENTION

The invention provides a progressive linkage used with a thumb mounted on a dipper stick for a prime mover such as an excavator. The progressive linkage for the thumb is mounted to the stick independent of the tool and tool linkage. More particularly, the idler link of the thumb progressive linkage is mounted to the dipper stick in a location with its pivot axis spaced from the pivot axis of the connection between the tool idler link and the dipper stick.

The invention provides a dipper stick carrying a tool and a thumb. The tool is connected to a tool actuator with a tool linkage having a tool idler link. The tool idler link is connected to the dipper stick at a tool idler link connection that has a pivot axis. The thumb is connected to a thumb actuator with a thumb linkage having a thumb idler link. The thumb idler link is connected to the dipper stick at a thumb idler link connection that has a pivot axis. The improvement of the combination includes the pivot axis of the thumb idler link connection being spaced from the pivot axis of the tool idler link connection.

In one configuration, the invention provides that the pivot axis of the thumb idler link connection is spaced outwardly from the inner surface of the dipper stick. The inner surface of the dipper stick is thus located between the pivot axis of the thumb idler link connection and the outer surface of the dipper stick.

In another configuration, the invention provides a progressive linkage that includes an idler link having a first end pivotably anchored to an anchor mount adapted to be secured to the inner surface of the dipper stick.

The invention also provides a configuration of a dipper stick thumb progressive linkage wherein the location of the connection between the thumb idler link and the dipper stick is independent of the connection between the tool and stick.

In another configuration, the invention provides a thumb progressive linkage having the connection between the thumb actuator and the thumb idler link disposed between the idler anchor location and the idler/power link connection. The idler/power link connection includes spaced apart arms that may be disposed on either side of the thumb actuator when the thumb is in the tuck position.

Another configuration of the invention provides a thumb progressive linkage wherein each of the power link and the idler link includes pairs of spaced link arms. Each of the individual arms of the power link is connected to only one of the individual arms of the idler link with short pins. This configuration allows a portion of the actuator to be disposed between the arms of the idler links when the thumb is in the tuck position thus increasing the range of motion for the thumb.

The invention also provides a method for mounting a progressive linkage for a thumb on a dipper stick.

The different aspects of these invention configurations may be used alone or in combination to define different inventive combinations.

Similar numbers refer to similar parts throughout the specification.

DETAILED DESCRIPTION OF THE INVENTION

The progressive linkage of the invention is indicated generally by the numeral2inFIGS. 6-12. Linkage2operatively connects a thumb actuator4to a thumb6to allow actuator4to control the movement of thumb6. Linkage2allows actuator4to move thumb6between tuck (FIG. 6) and reach (FIG. 8) positions.

In the exemplary configuration of the invention shown inFIGS. 6-12, thumb6is used in combination with a tool in the nature of a bucket11mounted the end of a dipper stick15. The tool in the configurations of this specification also may be a rake. Dipper stick15may be any of a variety of known devices and may be used with any of a variety of known prime movers13. Prime mover13may be an excavator such as the prior art device depicted inFIG. 1.

For the purpose of providing an exemplary environment in which linkage2may be used,FIG. 1depicts an exemplary prime mover13having an articulating boom12. InFIG. 1, an optional fast-make coupler10is used to connect bucket11to stick15. Coupler10is optional but may be used in combination with linkage2. Bucket11may be directly connected to stick15as shown in the other drawings. Articulating boom12may include proximal and distal boom arms14and15, respectively. The distal boom15is also referred to as a dipper stick15. The inboard end (not shown) of the proximal boom arm14is pivotally supported from prime mover13in a manner well known to the art. Proximal boom arm14may be raised and lowered about the inboard end thereof by an actuator (such as a piston cylinder actuator)16A that is pivotally connected between prime mover13and a pivot pin18A that may extend transversely through proximal boom arm14. The inboard end portion of dipper stick15is mounted to the outboard end of proximal boom arm14for articulation about a pivot pin18B. Articulation of dipper stick15may be selectively controlled by piston cylinder actuator16B. Specifically, one end of piston cylinder actuator16B is pivotally supported from the proximal boom arm14, as by pivot pin18C, and the other end of piston cylinder actuator16B is secured to a pivot pin18D that extends transversely through the lever arm portion of dipper stick15at the inboard end thereof.

As previewed in the previous paragraph, and as will be continued in the detailed description which follows, a particular structural member, component or arrangement may be employed at more than one location. When referring generally to that type of structural member, component or arrangement a common numerical designation shall be employed. However, when one of the structural members, components or arrangements so identified is to be individually identified it shall be referenced by virtue of a letter suffix employed in combination with the numerical designation employed for general identification of that structural member, component or arrangement. Thus, there are at least two actuators16associated with the articulating boom12. The actuators are generally identified by the numeral16, but the specific, individual, actuators are, therefore, identified as16A,16B, etc. in the specification and on the drawings. On some occasions a numerical subscript shall be employed after the letter suffix when it is necessary, or desirable, to distinguish (as to location) two items that might otherwise properly be designated by the alphanumeric combination of a common number with the same letter suffice. These suffix conventions shall be employed throughout the specification.

Returning toFIG. 1, it will also be observed that an articulating arm19is operatively associated with dipper stick15to effect pivotal movement of the coupler assembly10(this also may be used to pivot bucket11) about the outboard end of dipper stick15. Specifically, the inboard end of a tool idler link20is pivotally supported on a pivot pin18E that extends through dipper stick15, and the outboard end of the idler link20is pivotally connected not only to the actuator16C but also to the inboard end of articulating arm19, as by pivot pin18F. The other end of piston cylinder actuator16C is anchored to the inboard end portion of dipper stick15, as by pivot pin18G. As such, the piston cylinder actuator16C, in combination with the tie rod20, effects selective, pivotal movement of the coupler assembly10by relative movement of the articulating arm19with respect to dipper stick15.

FIGS. 2-5depict a prior art thumb50connected to an actuator52with a prior art progressive linkage54. In these drawings, thumb50and tool11are connected directly to the end of dipper stick15with a common pin55. Other mounting configurations also are known in the art. These include mounting thumb50directly to tool11with a pin and mounting thumb50directly to dipper stick15with its own pin at a location spaced from the pin that mounts tool11. Thumb50also may be used with coupler10. Progressive linkage2described below may be used with any of these mounting configurations.

Linkage54includes a power link56connected to thumb50and an idler link58anchored to dipper stick15. Idler link58is anchored to stick15with the same pin18E that anchors idler link20of tool11. A common long pin60is used to connect the ends of links56and58with the separate arms of power link56disposed between the ends of idler link58. Pin60is also used to receive the end of actuator52between the ends of the arms of power link56.

FIGS. 6-12depict progressive linkage2used with bucket11and thumb50. InFIGS. 6-10and12, bucket11and thumb50are pinned to the end of dipper stick15with common pin55. InFIG. 11, thumb50is mounted to stick15at a different location than bucket11. In theFIG. 11configuration, different pins are used to mount bucket11and thumb50. As noted above, progressive linkage2provides the connection between actuator52and thumb50.

Linkage2is anchored to dipper stick15at a location different than idler link20. Using a different connection point for linkage2allows linkage2to be designed for a wide variety of stick15, bucket11, and thumb50combinations. Instead of using the existing mounting pin and mounting location for the tool idler link, the invention provides an anchor mount for idler link100. The anchor mount may be secured directly to a surface of dipper stick15to provide pivotable support to idler link100. In the configuration of the invention depicted in the drawings, linkage2includes an anchor plate70that is used to secure linkage2to stick15. Plate70may be welded to the inner surface72of stick15to provide the structure for linkage2to pivot against. Anchor plate70is disposed outwardly (away from the middle) of inner surface72. The ends74of anchor plate70are non-parallel to the sides76of dipper stick15(ends74may be V-shaped) to prevent the welds from undesirably weakening dipper stick15. In the context of this specification, inner surface72of stick15is the face of stick15with thumb actuator52with the outer surface78being disposed on the opposite side where tool actuator16C is located. When viewed from the side as shown inFIGS. 7,9, and10, this configuration locates inner surface72of stick15between the pivot connection of linkage2and the outer surface78of dipper stick15. The anchor mount may be in the form of a plate such as plate70or other structures that provide pivotable support to a link such as flanges or bosses projecting from stick15.

As shown inFIGS. 8-10, linkage2includes a power link90connected to the yoke92of thumb50. In the exemplary configuration of linkage2, power link90includes a pair of arms90A and90B. The first end of each power link arm90A and90B is pivotably connected to yoke92with a pin96A and96B. Each pin96only needs to be long enough to pass through arm90and yoke92. Pins96A and96B are thus considered short pins and are thus less prone to bending than the long pin used in the prior art configuration ofFIG. 4wherein a single pin connected both arms of power link56to yoke92. In another configuration of linkage2, power link90may be in the form of a single arm connected to yoke92. Power link90thus includes at least one arm.

Linkage2also includes an idler link100having a first end pivotably anchored to dipper stick15via anchor plate70. In the exemplary configuration of linkage2, idler link100includes a pair of arms100A and100B. A common pin102is used to pivotably connect the first ends of idler arms100A and100B to a mounting structure that projects from plate70. Idler link100may be provided in the form of a single arm instead of the spaced arms shown in the drawings. Pin102is offset outwardly from inner surface72. Pin102is also spaced from pin18E such that linkage2is mounted independent of idler20. Idler link100thus does not have to be specifically designed to align with link20. Further, because the position of anchor plate70with respect to dipper stick15is not critical, it may be adjusted before welding to fit the particular combination of devices used with dipper stick15. This mounting configuration thus allows linkage2to be manufactured in a standard configuration that fits a variety of stick, tool, and thumb combinations. The mounting configuration also decreases the installation time because pin18E does not have to be removed and reassembled and because locating the correct position of anchor plate70with respect to stick15is easy and independent of the location of pin18E.

Actuator52is connected to idler link100at a location intermediate the first and second ends of idler link100. An actuator mounting pin110is disposed between arms100A and10B. Pin110pivotably receives actuator52. Locating pin110closer to pin102allows actuator52to be shortened and helps to protect the end of actuator52from damage while thumb50is in use. The drawings also show how the first ends of link arms100are disposed closer together than the width of dipper stick15at the location of the connection. Each link arm100may define an “S” bend so that the second ends of link arms100are spaced apart wider than the first ends. Reinforcing plates may be placed between arms100as shown inFIG. 8.

A pair of short pins120A and120B connect the second ends of idler link arms100A and100B to the second ends of power link arms90A and90B. Link arms100are disposed between the second ends of power link arms90and provide space to receive the end of actuator52as shown inFIG. 7when actuator52is retracted to completely open thumb50. This configuration provides a larger range of motion for thumb50as compared to the prior art linkage because the connections between arms90and100may be moved to a position where they are on either side of actuator52as shown inFIGS. 6,7and11.

The mounting configuration allows the linkage to be mounted to the dipper stick in a manner that saves considerable time over prior art linkages and mounting methods. As described above, the person mounting the linkage does not have to remove any portion of the tool linkage in order to mount the thumb linkage thus saving the time of disassembling and reassembling the tool linkage. In addition, the problem of locating the actuator on the dipper stick is solved because the actuator position is not directly related to the pivot axis between the tool idler link and the dipper stick. The actuator may be connected to the thumb linkage and the thumb is moved to its tuck position. Plate70and the actuator bracket are located on stick15with actuator52almost fully retracted. The thumb is then moved to its reach position and the locations are checked with respect to the extension of actuator52. If acceptable, the mounting locations are double checked and plate70and the actuator bracket are welded to dipper stick15.

In the context of this application, the term “include” has the same meaning as the term “comprise” with both terms being inclusive of the specific element mentioned without excluding other elements. In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.