Multi-function work machine

Abstract

A work machine having a first work member and a second work member, both operated from a pivotal control station. In a preferred embodiment the work machine has a backhoe assembly and a loader assembly both supported on a frame and operable from the pivotal control station. The work machine may have left and right low-profile drive systems that allow the first work member to perform work outside and parallel to the longitudinal center axis of the work machine. The work machine has a low-profile power source and operator platform that allow unobstructed visibility of the first and second work members from the control station.

Description

FIELD OF THE INVENTION

The present invention relates generally to multi-function work machines, and in particular to a compact multi-function work machine adapted to accept alternative work tools.

SUMMARY OF THE INVENTION

The present invention is directed to work machine comprising a frame, a first work member, a second work member, and a pivotal control station. The frame has a first end and a second end. The first work member is supported by the frame so that the first work member is operable at the first end of the frame. The second work member is supported by the frame so that the second work member is operable at the second end of the frame. The pivotal control station is supported by the frame and movable between at least a first position and a second position. The pivotal work station is adapted to control the first work member when in the first position and to control the second work member when in the second position.

The present invention further comprises an excavator. The excavator comprises a frame having a first end and a second end, a control station, a low-profile power source supported by the frame, and a control station also supported by the frame. A first work member is supported by the frame so that the first work member is operable at the first end of the frame and operated by the control station. A second work member is supported by the frame so that the second work member is operable at the second end of the frame and operated by the control station. The second work member comprises a lift arm and a work tool. The lift arm has a first end and a second end. The first end of the lift arm is pivotally connected to the frame. The second end of the lift arm is movable in a range of motion comprising a lower position and an upper position. The work tool is supported by the second end of the lift arm. The excavator further comprises a first unobstructed line of sight and a second unobstructed line of sight. The first unobstructed line of sight extends from the control station over the low-profile power source to the work tool when the second end of the lift arm is in the lower position. The second unobstructed line of sight extends from the control station to beyond the work tool when the second end of the lift arm is in the upper position.

The present invention further includes an excavator that comprises a frame, a low-profile left drive system and a low-profile right drive system. The low-profile left drive system and the low-profile right drive system are both supported by the frame and used to propel the frame in a plurality of directions. The excavator further comprises a first work member and a second work member. The first work member is supported by the frame so that the first work member is operable at the first end of the frame. The first work member comprises a swing arm, a swing post, a swing post actuator, and a swing arm actuator. The swing arm is pivotally connected to the frame and has a central longitudinal axis. The swing post is pivotally connected to the swing arm. The swing arm actuator is fixed to the frame and adapted to pivot the swing arm and swing post relative to the frame to a plurality of positions. The plurality positions includes at least one position placing the swing post beyond the left drive system and at least one position placing the swing post beyond the right drive system. The swing post actuator is fixed to the swing arm and adapted to impart a pivot motion to the swing post relative to the swing arm to either side of the central longitudinal axis of the swing arm such that the pivot motion of the swing post is not restricted by the position of the swing arm. The second work member is supported by the frame so that the second work member is operable at the second end of the frame.

Further still, the present invention includes a work machine comprising a frame, a pivotal control station, a pivotal first work member and a pivotal second work member. The frame has a first end, a second end and a longitudinal axis comprising a midpoint. The pivotal control station is supported by the frame and has a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis. The pivotal first work member is supported by the frame and has a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis of the frame. The pivotal second work member is supported by the frame and has a substantially horizontal pivot axis.

The present invention further includes an excavator comprising a frame having a first end and a second end, a pivotal control station supported by the frame, a first work member, and a second work member. The first work member is supported by the frame so that the first work member is operable at the first end of the frame. The first work member comprises a swing arm pivotally connected to the frame, a swing post pivotally connected to the swing arm, and a work tool supported by the swing post. The second work member is supported by the frame so that the second work member is operable at the second end of the frame. The excavator further includes an unobstructed line of sight extending from the control station to the work tool of the first work member.

Further still, the present invention includes, a work machine comprising a frame having a first end and a second end, a pivotal control station, a pivotal first work member, and a pivotal second work member. The control station is supported by the frame and has a substantially vertical pivot axis. The pivotal first work member is supported by the frame so that the first work member is operable at the first end of the frame. Further, the first work member comprises a substantially vertical pivot axis. The pivotal second work member is supported by the frame so that the second work member is operable at the second end of the frame and comprises a substantially horizontal pivot axis. The pivot axis of the control station, the pivot axis of the first work member, and the pivot axis of the second work member are disposed in relation to the frame to create a close-coupled work machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a multi-function work machine. The work machine has a first work member and a second work member both shown supported on a frame. The machine of FIG. 1 is equipped with a pivotal control station from which the first and second work members may be operated.

FIG. 2 is a perspective view of the frame of the work machine shown in FIG. 1. FIG. 2 illustrates positioning of the pivotal axes of the work members and the control station.

FIG. 3 is a perspective cut-away view of the frame of FIG. 2. FIG. 3 shows the attachment of the first work member to the frame. The first work member shown in FIG. 3 has a swing arm and a swing post used to support and move a work tool attached to the swing post.

FIG. 4 is a top view of the work machine of FIG. 1 illustrating alternate stowing positions of the excavator bucket.

FIG. 5 is a top view of the work machine of FIG. 4 having the roll-over protection canopy removed so that the operator's seat is visible. FIG. 5 illustrates the range of motion of the swing arm shown in FIG. 3.

FIG. 6 is a top view of the work machine of FIG. 5 illustrating the range of motion of the work tool when used with the swing arm and swing post of the present invention.

FIG. 7 is a top view of the work machine illustrating the use of the excavator bucket to dig a trench.

FIG. 8 is a side view of the work machine of FIG. 1 illustrating an unobstructed line of sight from the control station to the work tool.

FIG. 9 is a side view of the work machine of FIG. 1 illustrating an unobstructed line-of-sight from the control station to an excavator bucket positioned below ground.

FIG. 10 is a side view of the work machine illustrating a trencher as a work tool supported by the frame.

FIG. 11 is a side view of the work machine of the present invention having an offsetable vibratory plow as an alternate work tool supported by the frame.

FIG. 12 is a side view of the work machine having an alternative configuration. The work machine of FIG. 12 has a “dump bed” attached to the work member.

DESCRIPTION

Turning now to the figures and first to FIG. 1, there is shown therein a work machine 10 of the present invention. The work machine 10 shown in FIG. 1 is an excavator that, among other things, may be used to dig trenches and move earth. The work machine 10 comprises a frame 12 having a first end 14 and a second end 16. The frame 12 supports a first work member 18 and a second work member 20. The first work member 18 is supported by the frame 12 so that it is operable at the first end 14 of the frame. The second work member 20 is supported by the frame 12 so that it is operable at the second end 16 of the frame. The work machine 10 of FIG. 1 further includes a control station 22 supported by the frame 12. The control station 22 is movable between a first position A and a second position B. When placed in position B the control station 22 controls the function of the first work member 18. The second work member 20 is controlled by the control station 22 when the control station is in position A.

The first work member 18 may comprise a tool carrier 24. The tool carrier 24 may comprise a swing arm 26 connected to the frame 12, a swing post 28 connected to the swing arm, and a work tool connected to the swing post. For purposes of illustration, the work tool of FIG. 1 is a backhoe attachment used to dig trenches. The backhoe comprises a boom 30, a dipper 32, and an excavator bucket 34. The boom 30, dipper 32 and bucket 34 are pivotally connected in series and positioned or moved with respect to each other using hydraulic cylinders 36, 38, and 40. The backhoe attachment is moved and positioned relative to the frame 12 by moving the swing arm 26 and swing post 28. The swing arm 26 may have a swing arm actuator 42 comprising a hydraulic cylinder that is adapted to pivot the swing arm and the swing post 28 relative to the frame 12 to a plurality of positions. A swing post actuator 44 (FIG. 3) may be fixed to the swing arm 26 and adapted to impart pivot motion to the swing post 28 relative to the swing arm 26.

The second work member 20 may comprise a tool carrier 46. The tool carrier 46 may be constructed to support a variety of alternative work tools. For illustrative purposes, the work tool shown attached to the tool carrier 46 in FIG. 1 is loader bucket 48. The tool carrier 46 and loader bucket 48 are supported by one or more lift arms 50 having a first end 52 and a second end 54. Each lift arm 50 is pivotally connected to the second work member support 56 of the frame 12 at pivot point 58. The second end 54 of the lift arm 50 is movable in a range of motion comprising a lower position (shown in FIG. 1) and an upper position. The lift arm 50 may be raised and supported at any position within its range of motion using a lift arm actuator 60. The lift arm actuator 60 is attached to the second work member support 56 at pivot point 62 and to a bracket 64 supported at the second end 54 of the lift arm.

The tool carrier 46 may comprise a quick-attach mechanism adapted to connect to a wide variety of work tools such as the loader bucket 48 shown in FIG. 1. The angular rotational position of the work tool 48 may be adjusted or held at a desired “tilt” (“curl”) angle by a tilt cylinder 66 connected to the tool carrier 46 and a tilt cylinder bracket 68 supported by the lift arm 50. It will be appreciated that the lift arm 50 may be telescopic at its second end 54 for extended reach and lift height of the work tool 48.

Continuing with FIG. 1, the work machine 10 further may comprise a low profile power source 70 supported by the frame 12. The low-profile power source 70 may comprise an internal combustion engine (not shown) supported within an engine compartment 76. It will be appreciated, of course, that different type engines or power sources may be used to power the work machine 10. The power source 70 is adapted to drive operation of the left 72 and right 74 drive systems, and the various hydraulic and electrical systems used with the work machine 10. The engine compartment 76 of the low-profile drive system 70 is sloped such that a first line-of-sight between the control station 22 and the work tool 48 is unobstructed when the control station is in position A and the work tool is in the lower position shown in FIG. 1. However, it will be appreciated that the lift arm 50 may be constructed in such a manner that a second unobstructed line-of-sight extends from the control station 22 to beyond the work tool 48 when the second end 54 of the lift arm 50 is in the upper position (not shown).

The frame 12 is adapted to support a low-profile left 72 and right 74 (FIG. 5) drive system. The low-profile left 72 and right 74 drive systems are both supported by the frame for propelling the frame in a plurality of directions. The drive systems 72 and 74 shown in FIGS. 1 and 5 comprise an all-terrain endless track system. However, it will be appreciated that the left 72 and right 74 drive systems may each comprise a plurality of low-profile wheels that are capable of being steered in a skid, articulated, coordinated or conventional arrangement without departing from the spirit of the invention.

Referring still to FIG. 1, the pivotal control station 22 is supported by the frame 12 and may comprise an operator seat 78 having a vertical pivot axis 80. A plurality of controls 82a and 82b may be supported on the control station 22 and, more specifically, disposed on the operator's seat 78 for rotation therewith. The controls 82a and 82b are adapted to control operation of both the first work member 18 and the second work member 20.

The control station 22 may further comprise a roll-over protection structure (“ROPS”) 84 supported by the frame 12. The ROPS 84 is preferably a front-cantilevered canopy having two vertical posts 86 and 88. Use of the two-post front-cantilevered canopy ROPS 84 provides improved visibility of both the first work member 18 or the second work member 20 during the operation of each. Alternatively, the ROPS may have three or more vertical posts or other ROPS structure configurations positioned to allow improved visibility.

The process of switching the on-seat controls 82a and 82b from functional operation of the first work member 18 to operation of the second work member 20 (or vice versa) will now be described. Switching of operation may be initiated by a function selector switch (not shown). In a first position of the switch, the on-seat controls 82a and 82b operate a hydraulic circuit powering the above-mentioned drive systems (via a left joystick) while also being available to actuate the movements of the second work member 20 (via the right joystick). In the second position of the function selector switch, the on-seat controls 82a and 82b operate the movements of the first work member 18. Actuation of the switch causes a pilot pressure controlled diverter valve (not shown) in each of two control valve sections to switch their operative control to the first work member 18 or to the second work member 20. Additionally, the switch may cause a seat-mounted valve manifold 79 to shift the operative control of the left control 82a between control of the drive systems 72 and 74 and control of certain actions of the first work member 18. The operative control provided by the controls 82a and 82b are summarized below.

In accordance with the present invention, there may be two basic modes of operation of the work machine 10. Mode 1 involves the second work member 20 and the drive systems 72 and 74, while Mode 2 applies to the first work member 18. In operational Mode 1 the left control 82a may operate the drive systems 72 and 74 by pilot control of their respective hydrostatic pumps. Forward movement of the left control 82a causes the work machine 10 to move forward. Rearward movement of the left control 82a causes the work machine 10 to move rearward. The speed attained by the work machine 10 is related to the amount the left control 82a is displaced from its neutral position. Charge circuit pressure from one of the hydrostatic pumps flows through the displaced left control 82a to control the stroking of each hydrostatic pump. Left-right motion of the left control 82a causes the work machine 10 to steer in the respective direction. When the left control 82a is at either extent of its lateral motion, counter-rotation of drive systems 72 and 74 may cause a zero turning radius to be accomplished in the associated direction.

In operational Mode 1, the right control 82b may operate the actions of the second work member 20. In this instance (and similar ones described below), the charge circuit pressure flowing through the displaced right control 82b causes the pilot-operated displacement of one or more valve spools in the main control valve. The following description is given for the specific case of the second work member 20 comprising a loader. Forward and rearward displacement of the control 82b from its neutral position causes the lift arms 50 to raise and lower, respectively. Left and right displacement of the control 82b causes the loader bucket 48 to curl upward to contain a payload, or tilt (uncurl) to accept or discharge a payload.

A toggle switch (not shown) on top of the control 82b may control the flow of hydraulic power to an accessory tool that might be mounted on the first 18 or the second work member 20—for instance a posthole digger, pavement breaker, or the various work tools described hereinafter. The toggle switch may comprise a three-position rocker switch, where the tool activating (ON) position is detented and the opposite OFF position is spring returned to neutral. Whenever an operator is not properly seated in the seat 78, an operator presence sensing system in the seat may cause the toggle switch and the controls 82a and 82b to power down. The system disabling shut-down may be contained within the valve manifold 79.

Continuing with FIG. 1 the second operation mode (Mode 2) will be described with reference to the use of a backhoe assembly for purposes of illustration. The repositioning of the function selector switch will cause the left control 82a to operate the boom 30, the offsetting action of the swing arm 26, and the swing action (side to side pivoting) of the swing post 28. Displacement of the control 82a longitudinally toward the operator raises the boom 30, while pushing away from the neutral position lowers the boom. Displacement of the control 82a laterally inward toward the operator causes the swing arm 26 to offset the first work member 18 toward the operator's right, while an outward lateral motion moves the swing arm 26 oppositely, for placement of the bucket 34 in a desired position on or laterally offset from the longitudinal centerline 83 (FIG. 2) of the frame 12.

A toggle switch (not shown) on top of the left control 82a controls pivotal movement of the swing post 28 and the boom 30 attached thereto. Pressing on the portion of the rocker switch nearest to the operator causes the boom 30 to swing toward the operator's right, while pressing on the outer portion moves the boom oppositely.

In Mode 2, the right control 82b controls the movement of the dipper 32 and the backhoe bucket 34. Displacement of the control 82b longitudinally toward the operator causes the dipper 32 to move similarly, likewise in the case when moving the control 82b away from the neutral position. Displacement of the control 82b laterally inward toward the operator causes the backhoe bucket 34 to curl inward toward the operator; an outward lateral motion uncurls the bucket.

Alternatively, the controls 82a and 82b could function electronically. Such a joystick or other type of electronic actuator senses hand-motion direction and distance inputs from the operator and sends correlated electrical signal(s) to a controller, which commands the activation of electro-hydraulic valve(s) and/or the output of variable displacement pump(s). One skilled in the art understands that the output response from a valve or pump is usually hydraulic flow rate, in a response proportional to the input signal. (It is also understood that signals from controls 82a and 82b could directly activate electro-hydraulic valves without use of a controller.) An electro-hydraulic valve also typically delivers a hydraulic flow rate to the circuit it controls in proportion to the input signal. Electronic control of selected functions enables their automatic control and eases the switching of control function assignments to suit operator preferences. For example, two common backhoe control patterns are described as ISO and SAE standard control patterns. These could be selected by simply switching the routing of the control signals via a physical switch or by software within the controller.

The above-mentioned controller may be programmed to automate certain functions of the work machine 10. For example, it may be desirable to deposit spoils excavated by the first work member 18 a distance from the excavation. Combined pivotal movement of the swing arm 26 and the swing post 28 can accommodate this desire. The motion-to-function assignments of control 82a—lateral motion: swing arm 26; toggle switch: swing post 28—could be simplified by an operator selectable “coordinated movement” control algorithm. In this operating mode, the coordinated movement of the swing arm 26 and the swing post 28 could be initiated solely by lateral motion of the operator's left hand. As used here, “coordinated movement” refers to simultaneous or sequential amounts of rotation about the respective pivot axes of the swing arm 26 (pivot axis 94) and the swing post 28 (pivot axis 112). Their simultaneous coordinated movement may be in a proportional relationship that is lesser than, greater than, or equal to 1:1. The preferred proportional setting—being site dependent—is one that pivots the first work member 18 back and forth between the excavation alignment and the spoil pile without need of manually adjusting the angular relationship between the swing arm 26 and the swing post 28 at either extent of their coordinated movement. This is particularly important at the point of excavation. The boom 30 must be in near parallelism with the desired alignment of the excavation whenever the backhoe bucket 34 is poised to be lowered into the excavation. This can be assured by implementing a “return to dig” subroutine that automatically returns the swing arm 26 and the swing post 28 to their respective angular orientation equating to the excavation alignment. These two “return to dig” angular parameters can be set or input by the operator by one of several commonly known techniques. For instance, when initially placed in the desired positional alignment, the press of a button could cause recording of readings from angular position sensors (e.g., angular encoders or potentiometers) mounted at the two pivot axes. The controller would bring the boom 30 back to this position—after it observes a sequence of electrical control signals representing actions related to lifting, swinging, and opening the backhoe bucket 34 to deposit its contents at the spoil pile—upon the operator's lateral movement of the left control 82a in the direction associated with movement toward the excavation. The “return to dig” subroutine would stop the respective angular motions at their set points even though the operator may continue to hold the left control 82a laterally displaced. Motion could be stopped prior to reaching these set points by a brief lateral displacement of left control 82a in the opposite direction. The “return to dig” subroutine may be utilized separately from the complete “coordinated movement” control cycle. For instance, automated coordinated angular movement of the swing arm 26 and the swing post 28 directed away from the point of excavation may not be particularly helpful in situations where the desired position and/or elevation for depositing the spoil varies from one cycle to the next, or even less frequently.

A useful modification (adaptation) of the “return to dig” subroutine is to equally and oppositely coordinate the angular motions of the swing arm 26 and the swing post 28 whenever they are moved away from coincidence with the longitudinal central axis of the work machine 10. In other words, the controller holds all offset positions of the first work member 18 in parallel alignment with the longitudinal central axis 83 of the frame 12 by utilizing a feedback control loop that continually monitors readings from the two angular position sensors. This “parallel offset” subroutine is particularly advantageous if a trencher or offsetable vibratory plow is attached to the swing arm 26. Automated control of parallelism releases the attention of the operator to focus on other important operational tasks. In cases where it is desired that rear work tools of the work machine 10 be solely utilized in parallel alignment, a “mechanized” parallel offset could be accomplished without controller automation.

Turning now to FIG. 2 there is shown a perspective view of the frame 12 from its first end 14. The frame 12 may be of a box-like construction comprised of several horizontal and vertical plates. The frame 12 may further comprise a longitudinal axis 83 comprising a midpoint 85. The plates may comprise the operator platform plate 89, a power source support plate 90, a pair of vertical support plates 91 and 92, and the second work member supports 56. The cross-braced, box-like construction illustrated in FIG. 2 provides torsional rigidity in reacting to the working forces exerted on the frame 12 during operation of the work machine 10. The use of single plate construction for commonly transferring loads and mounting components contributes to compactness and simplicity of the work machine 10.

Continuing with FIG. 2, the frame 12 may also comprise a pedestal 93 supported on the operator's platform 89 and adapted to support the operator's seat 78 (FIG. 1). The pedestal 93 may be disposed coaxially with the vertical pivot axis 80 of the control station 22. As shown in FIG. 2, the vertical pivot axis 80 of the control station 22 (FIG. 1) may be disposed along the longitudinal axis 83 of the frame 12 such that it intersects the longitudinal axis. The vertical pivot axis 94 of the first work member 18 (FIG. 1) is likewise disposed along the longitudinal axis 83 of the frame 12 and passes through a yet to be described first work member 18 mounting assembly.

The vertical side plates 91 and 92 support the second work member supports 56 and a gauge panel 96. The second work member supports 56 may be welded to the outer surface 98 of vertical side plates 91 and 92. The second work member supports 56 may have openings 101 and 102 for mounting the second work member 20 to the frame 12. Thus, when mounted to the frame 12, the second work member 20 comprises a substantially horizontal pivot axis 103 disposed in relation to the longitudinal axis 83 of the frame 12. In FIG. 2, the horizontal axis 103 is arranged perpendicular to the longitudinal axis 83 of the frame 12. It will be appreciated that the box-like construction of the frame allows the pivot axis 80 of the control station 22, the pivot axis 94 of the first work member 18, and the pivot axis 103 of the second work member 20 to be disposed in relation to each other to create a close-coupled work machine in accordance with the present invention. It will be further appreciated that the pivot axis 94 of the first work member 18 and the pivot axis 103 of the second work member 20 may be disposed such that the axes substantially overlap.

The gauge panel 96 is shown welded to an inner surface 100 of the vertical side plates 91 and 92. The gauge panel 96 may have cutouts 104 of varying size and configurations to accommodate the presence of various gauges and controls.

Turning now to FIG. 3, there is shown therein a partially cut-away view of the frame 12 shown supporting the first work member 18. The first work member 18 is supported between the operator's platform 89 and the power source plate 90. The first work member 18 of FIG. 3 generally comprises the swing arm 26 pivotally connected to the frame 12 and a swing post 28 pivotally connected to the swing arm 26. The swing arm 26 is attached to the frame 12 by a swing arm mounting pin 106 with upper 108 and lower 110 support bushings. The swing arm cylinder 42 (See FIG. 1) is connected to the frame 12 and the swing arm 26 and provides swing force to the swing arm to move it about the pivot axis 94. However, it will be appreciated that other mechanisms such as a rotary actuator may be used to provide the swing force used to move the swing arm 26 without departing from the spirit of the invention.

As previously discussed, the swing arm 26 has an unimpeded range of offset positions. The swing arm 26 arrangement of FIG. 3 is bound only by the swing arm's points of contact with the vertical side plates 91 and 92 and by the extended and retracted range of the swing arm cylinder 42. The pivot axis 94 of the swing arm 26 is shown for purposes of illustration laterally centered within the frame 12 to allow substantially the same amount of offset left or right for the first work member 18. As will be discussed with reference to FIG. 5, the swing arm's 26 range of motion allows the swing arm cylinder 42 to pivot the swing post 28 and swing arm to a position beyond the left drive system 72 and/or beyond the right drive system 74.

The swing post 28 is supported on the swing arm 26 and pivotal about pivot axis 112. The swing post 28 may comprise several mounting points 114 and a swing post cylinder bracket 116. The mounting points 114 may support the work tool for operation at the first end 14 of the frame. For example, the mounting points may be adapted to connect the boom 30 and cylinder 36 of the backhoe assembly to the work machine 10. The swing post cylinder bracket 116 extends laterally from the swing post 28 and provides a connection point for the swing post cylinder 44. The opposing end of the cylinder 44 is connected to a bracket 118 pivotally supported on the swing arm 26. Connection of the cylinder 44 to the swing arm 26 allows the cylinder to impart a pivot motion to the swing post 28 relative to the swing arm to either side of the swing arm such that the pivot motion of the swing post is not restricted by the position of the swing arm.

Turning now to FIG. 4, the work machine 10 of the present invention is shown from the top having the work tool 34 of the first work member 18 in a stowed “Position A”. The swing arm 26 is positioned to the left side (operator's right when facing the first end 14 of the frame 12) of the work machine 10 and the swing post cylinder 44 (FIG. 3) is fully retracted. However, the swing post cylinder 44 may be replaced with a conventional rotary actuator swing mechanism (not shown), to increase the range of motion to the stow position of the work tool 34 in “Position B”. The “minimum overhang” stow positions shown at Positions A and B improves the functional utilization of the first work member 18 in space-limited applications. The first work member 18 may be stowed with the swing arm 26 at the opposite point in its travel, or anywhere in between. The operator may utilize this feature to enhance the side slope stability of the work machine 10 while maneuvering around a job site and/or during operations of the second work member 20. It will be appreciated that the addition of appropriate stability (slope) sensors will allow for automatic altering of the stow position by a control system such as described hereinafter. Alternately, a stow position where the swing arm 26 of the first work member 18 is aligned with the longitudinal axis 83 of the frame 12 will offer enhanced counter-balance to the breakout force and lift capacity of the second work member 20. As previously discussed, the swing arm 26 may be moved beyond the left drive system 72 and the right drive system 74. However, stowing positions preferably retain the swing arm 26 of the first work member 18 inboard of those boundaries to maintain a narrow lateral profile for the work machine 10.

With reference now to FIG. 5, the work machine 10 is shown from the top with the ROPS 84 cut-away. In FIG. 5 the first work member 18 is shown in Positions C and D to illustrate the range-of-motion of the first work member when moved by the swing arm cylinder 42 and swing post cylinder 44. The swing arm cylinder 42 may be utilized to position and hold the swing arm 26 laterally (left or right) anywhere within an arc of motion substantially bisected by the longitudinal axis 83 of the frame 12.

A lock (not shown) may be provided to hold the swing arm 26 in position once set in a desired operating or stow position. A suitable lock may be, for instance, a hydraulic or otherwise-actuated device such as a frictional clamp (brake), a multi-positional latch, or simply the pinning of the arm 26 to the frame 12 or the operator's platform 89. Alternately, the swing arm lock could be a closed-loop control system consisting of one or more sensors to determine position of the swing arm 26, an operator interface (not shown) for the operator to input the desired position, and appropriate control circuitry and logic. The control system receives the input position signal and activates the swing arm cylinder 42 to bring the swing arm 26 to the desired position. A “set” signal from the operator would cause the control system to monitor the sensor output(s) and assure the arm 26 stays in position by activating the swing arm cylinder 42 as may be required to hold the desired position. The stored position point may also be useful for returning the swing arm 26 to the same position time after time. This may ease the burden on the operator in the case where cooperative use of the swing arm cylinder 42 and the swing post cylinder 44 is employed to position the payload discharge of the work tool 34 (backhoe bucket) at a point of greater arcuate reach. Suitable position sensors would include a rotary potentiometer on the swing arm 26 or a linear motion transducer contained on or within the swing arm cylinder 42.

In FIGS. 5 and 6, the arcuate reach of the boom 30 (FIG. 1 and thus that of the first work member 18—is illustrated as being at least 260 degrees total, 130 degrees either side of longitudinal axis 83 of the frame 12. This reach represents the cooperative, combined pivotal motion of the swing arm 26 and the swing post 28 about their respective pivot axes 94 and 112. The first work member 18 comprising the backhoe assembly can create an excavation in a desired direction within the angular bounds of Position C and Position D, while depositing the excavated spoil at another location within those bounds. It may also create an excavation that is substantially parallel to the longitudinal axis 83 of the frame 12 anywhere within the bounds of Position E and Position F of FIG. 6. The lateral extent (offset) of these two positions is dependent upon the amount of arcuate motion available to the swing post 28—through the action of the swing post cylinder 44. The offset of Positions E and F are also dependent upon considerations related to the swing arm 26 described below.

Referring still to FIGS. 5 and 6, the arc of motion of the swing arm 26 about its pivot axis 94 is preferably of a sufficient degree to allow the first work member 18 to perform its work function(s) along a line substantially parallel to and laterally outside of either the left 72 or right 74 drive system. At any particular offset alignment, this is accomplished by extending or retracting swing post cylinder 44 such that the swing post 28 rotates (positions) the work tool 34 into parallel (though offset) alignment with the longitudinal axis 83 of the frame 12. As illustrated in FIGS. 5 and 6, the full range of motion of the swing arm 26 is 130 degrees of arc. This allows work to be performed centered on a line outside of either the left drive system 72 or the right drive system 74. Within the bounds of machine stability considerations, the necessary amount of arc is primarily dependent upon the overall width of the drive systems 72 and 74, the desired lateral distance outside the drive systems 72 and 74 to perform work, and the length of the swing arm 26. The overall width of the drive systems 72 and 74 might be a single (fixed) value, may have given values for each tread width available for the endless tracks, or—for an adjustable undercarriage—may be of variable width. The arc of motion and length of the swing arm 26, including being of a telescoping configuration, may be determined in a tradeoff relationship affected by other design variables, such as available space for supported placement of the swing arm pivot axis 94.

Turning now to FIG. 7, there is shown therein the work machine 10 of the present invention excavating a trench shown with dashed lines 120. The trench 120 is shown offset outside the track 72 and is parallel to the digging alignment of the boom 30, the dipper 32, and the backhoe bucket 34.

The first work member 18 may be positioned at the offset position shown in FIG. 7 by pivotal action of the swing post 28 and the swing arm 26. Once the boom 30 is aligned longitudinally parallel to the longitudinal axis 83 of the frame 12 by pivotal action of the swing post 28 and swing arm 26, the excavation proceeds by coordinated actions of the boom 30, the dipper 32, and the bucket 34. Discharge of spoil from the bucket 34 may be accomplished by arcuate repositioning of the backhoe through pivotal action of the swing post 28 or of the swing arm 26. The combined pivotal action of the swing post 28 and the swing arm 26 may be useful in instances where one desires the spoil pile to be further displaced from the excavation. In the illustration of FIG. 7, depositing of spoil toward the machine centerline side of the excavation will substantially involve pivotal action of the swing arm 26, as the swing post 28 may have limited remaining motion available in that direction. Conversely, depositing spoil laterally beyond the excavation will substantially involve pivotal action of the swing post 28 since the swing arm 26 may already be in a fully offset position. Alternate tools such as a plow (shown in FIG. 11) may be positioned in much the same way as illustrated in FIG. 7—thus allowing the tool to operate beyond the left drive system 72 or the right drive system 74. This arrangement is advantageous when working along an obstruction such as a wall.

Aided by the laterally offsetable first work member 18, the work machine 10 equipped with an independently adjustable width drive system can be “walked” sideways for close maneuvering in tight quarters. With the swing arm 26 positioned toward the side of the desired direction of machine sideways movement, toward the left in this example, the backhoe bucket 34 can be pressed downward to lift the left side of the machine 10 slightly off the ground while the left drive system 72 is extended. At the same time, the right drive system 74 may be extended to move the machine 10 toward the left. The swing arm 26 may then be moved to the right (opposite) side of the machine 10 to slightly lift the right drive system 74. The width of the left drive system 72 may then be narrowed to move the machine 10 an additional increment toward the left. Narrowing the right drive system 74 at this time brings the drive system back to its starting position or into position for another sideways movement. A width that is simultaneously rather than independently adjustable can also be utilized to walk the machine 10 sideways in a similar manner. One skilled in the art can readily modify the above procedure to accommodate the situation where the machine 10 initially has its variable width undercarriage fully extended.

Turning now to FIG. 8, there is shown therein the work machine 10 of the present invention with an operator 122 seated at the control station 22. The operator 122 shown in FIG. 8 may be generally characterized as a 95^th percentile male operator. FIG. 8 illustrates the forward 2 visibility of the second work member 20 and the loader bucket 48. The steep forward slant to the engine compartment 76 provides the operator 122 with an unobstructed line of sight 124 of the bucket 48 when the lift arms 50 are in the lowered position. The slant of the engine compartment 76 approximately parallels the operator's line of sight 124. Adjustment of the operator's seat 78 would further improve visibility. Such an adjustment is practical even for larger operators 78 because of placement of the controls 82 on the seat, rather than on a console. Perforating a portion of the ROPS 84 (FIG. 4) canopy provides the operator 122 with improved visibility of the bucket 48 when the lift arms 50 are in the upper position.

Positioning of the low-profile power source 70 in relation to the operator's line-of sight 122 helps to achieve the unobstructed line-of-sight illustrated in FIG. 8. Lower positioning of the power source 70 is accomplished, in part, by driving the left drive system 72 and the right drive system 74 at their respective inboard rearward ends. This arrangement provides a clear space between the forward end of the left drive system 72 and the right drive system 74, where the lower part of the frame 12 (FIG. 2)—i.e., the vertical side plates 91 and 92 and the engine support plate 90—can lay, as illustrated in FIG. 2. For purposes of illustrations, forward ins the direction the operator 122 is facing in FIG. 8. An engine-pump assembly (described hereinafter) is disposed between the vertical side plates 91 and 92 of the frame 12, partially nested between the left drive system 72 and the right drive system 74. The engine compartment 76 can thus be forward-sloped for improved operator visibility-towards the second work member 20.

Side-by-side arrangement of the engine-pump assembly (not shown) within the engine compartment 76 shortens the engine compartment and the second end 16 of the frame 12. The second work member supports 56 can thus be placed further rearward on the frame 12. The shortened first 14 and second 16 ends of the frame 12 are further complemented by a condensed central portion, made possible by the compact length of the operator platform 89. Its compact length is primarily the outcome of utilizing the on-seat controls 82 instead of pedestal-mounted controls for the first and second work members 18 and 20.

Continuing with FIG. 8, the downward sloped shroud of the engine compartment 76 is possible because the drive system components (not shown) are mounted low within the frame 12, on the power source plate 90 (See FIG. 2). It will be appreciated that the power train components may comprise an engine-powered hydrostatic pump assembly configured with an axial “stack” of two hydrostatic pumps (one to drive each of the left drive system 72 and the right drive system 74) and an auxiliary pump supported along side a rearward-facing engine. The side-by-side arrangement of the engine and hydraulic pumps shortens the engine compartment 76 and, likewise, the second end 16 of the frame 12.

Referring now to FIG. 9, the operator's visibility of the first work member 18 is illustrated. FIG. 9 depicts the work machine 10 with a backhoe first work member 18 near its full digging depth, in alignment with the longitudinal axis 83 of frame 12. The operator's unobstructed view 126 of the backhoe bucket 34 is indicated by a dashed line. The openness of the operator platform 89 is particularly apparent with the backhoe assembly in its lowered position. It will be appreciated that the operator's view 126 over the operator platform 89 can be improved by readjusting the seat 78 towards the first work member 18.

It will be appreciated that the operator's line-of-sight 126 remains substantially unobstructed when the first work member 18 is deployed for excavating parallel to the longitudinal axis 83 of the frame 12 outside either of the drive systems 72 and 74. Essentially the operator's knees may comprise the only obstruction to his/her view of the bucket 34. The work machine 10 offers unobstructed operator visibility of the first work member 18 in any of its possible working positions shown in FIGS. 5 and 6.

With reference now to FIG. 10, there is shown therein an alternative configuration of the work machine 10 of the present invention. The work machine 10 of FIG. 10 comprises the first work member 18 having a backhoe assembly supported thereon and the second work member 20 comprising a trencher 128 supported by the tool carrier 46. In this arrangement, the machine 10 travels rearward while trenching. The operator may face the operator's seat 78 in that direction, as shown. However, facing the seat 78 toward the left or right side of the machine 10 offers improved visibility of the trencher 128 and the path to be traveled.

It will be appreciated that one or more tools or work members are suitable for mounting at either end of the work machine 10. Although not illustrated, one or more quick-attach mechanisms (tool carrier adapters) could also be configured with the first work member 18. For instance, a quick-attach mechanism could be mounted between the dipper 32 and the rear work tool (backhoe bucket) 34. The bucket 34 may then be quickly replaced with other tools or work members suitable for boom-mounting. These may include an offsetable vibratory plow, a trencher 128, and other devices such as a compaction wheel, a vibratory compactor, or a pavement breaker. Mounting of trencher 128 at the distal end of the dipper 32 would allow the trencher to be utilized above or below the ground's surface, and/or at extended lateral reach.

A quick-attach mechanism 130 could also be mounted to the swing post 28 to facilitate conversion to a more closely-coupled but offsetable tool, such as the vibratory plow 132 shown in FIG. 11. In this case, the swing arm 26 in conjunction with the swingable attachment frame 134 (and their hydraulic cylinders 42 and 44) provides the lateral offset capability. A lifting mechanism (not shown), to raise and lower the plow 132, is also contained within the attachment frame 134. A similar arrangement may be utilized for supporting a trencher 128 from the swing arm 26.

Turning now to FIG. 12, yet another configuration for work machine of the present invention is illustrated. In work machine 10 of FIG. 12 the second work member 20 is shown supporting a dump bed 136. The dump bed 136 is configured to be located above the engine compartment 76 of the work machine 10. The contour of the rear lower portion of the dump bed 138 is designed to generally follow the contour of the engine compartment 76 and lift arms 50. This contour and the fact that the dump bed 136 is located above the engine compartment 76 moves the center of gravity (CG) 140 of the dump bed closer to the CG of the work machine 10. This allows more weight to be carried in the dump bed 136 when moving the load from one location to another, compared to the load that could be carried with a more normal bucket configuration (i.e., further out in front of the machine 10). Discharge cylinders 142 provide a dumping force to tilt the dump bed 136 to allow the material 144 contained within to be dumped on the ground and to thus empty the dump bed 136. During the operation of dumping, the CG 140 of the dump bed 136 moves forward. To reduce the chance of the machine 10 tipping forward, a support plate 146 may be lowered to contact the ground by the activation of cylinder(s) 148.

It will be appreciated that the dump bed 136 may be detached from the unit by disconnecting the tilt arm cylinder(s) 142 and removing attachment pins 150. In this arrangement, the dump bed 136 may be fitted with at least one removable support leg 152. The support leg and the base of the bed 136 allow the dump bed to sit upright on the ground. In this way the dump bed 136 could be filled by another machine or by hand while the work machine 10 is being used elsewhere. Alternately, the dump bed 136 could be filled by use of the first work member 18 or second work member 20. Once filled with material, the dump bed 136 may be picked up again by the machine 10 and transported to another location to deposit the material. A similar “over the engine compartment 76” configuration could be used for some other attachments when additional weight or bulk must be carried—for instance, a flat pallet for carrying sacks or roofing materials, or a concrete transporter.

Various modifications can be made in the design and operation of the present invention without departing from the spirit thereof. Thus, while the principal preferred construction and modes of operation of the invention have been explained in what is now considered to represent its best embodiments, which have been illustrated and described, it should be understood that the invention may be practiced otherwise than as specifically illustrated and described.

Claims

1. A work machine comprising: a frame having a first end and a second end; a first work member supported by the frame so that the first work member is operable at the first end of the frame; a second work member supported by the frame so that the second work member is operable at the second end of the frame; a pivotal control station supported by the frame and movable between at least a first position and a second position and adapted to control the first work member when in the first position and to control the second work member when in the second position.

2. The work machine of claim 1 wherein the second work member comprises a tool carrier.

3. The work machine of claim 2 further comprising a work tool supported by the tool carrier.

4. The work machine of claim 1 wherein the first work member comprises a tool carrier and wherein the second work member comprises a tool carrier.

5. The work machine of claim 1 wherein the pivotal control station comprises a plurality of controls supported on the control station, the controls being adapted to control operation of the first work member and the second work member.

6. The work machine of claim 5 wherein the control station comprises a pivotal operator seat and wherein the plurality of controls are disposed at the operator seat.

7. The work machine of claim 1 comprising a low-profile power source supported by the frame.

8. The work machine of claim 7 wherein the second work member comprises: a lift arm having a first end and a second end, the first end being pivotally connected to the frame, and the second end being movable in a range of motion comprising a lower position and an upper position; and a work tool supported by the second end of the lift arm.

9. The work machine of claim 8 wherein the work tool comprises a loader bucket.

10. The work machine of claim 8 further comprising: a first unobstructed line of sight extending from the control station over the low-profile power source to the work tool when the second end of the lift arm is in the lower position; and a second unobstructed line of sight extending from the control station to beyond the work tool when the second end of the lift arm is in the upper position.

11. The work machine of claim 1 further comprising a low-profile left drive system and a low-profile right drive system, both systems being supported by the frame for propelling the frame in a plurality of directions.

12. The work machine of claim 11 wherein the left and right drive systems each comprise an endless track.

13. The work machine of claim 11 wherein the left and right drive systems each comprise at least two low-profile wheels and wherein the wheels can be steered in a skid arrangement.

14. The work machine of claim 11 wherein the first work member comprises: a swing arm pivotally connected to the frame, the swing arm having a central longitudinal axis; a swing post pivotally connected to the swing arm; a swing arm actuator fixed to the frame and adapted to pivot the swing arm and swing post relative to the frame to a plurality of positions, the plurality of positions including at least one position placing the swing post beyond the left drive system, and at least one position placing the swing post beyond the right drive system; and a swing post actuator fixed to the swing arm and adapted to impart a pivot motion to the swing post relative to the swing arm to either side of the central longitudinal axis of the swing arm such that the pivot motion of the swing post is not restricted by the position of the swing arm.

15. The work machine of claim 1 wherein the frame comprises a longitudinal axis comprising a midpoint; wherein the pivotal control station comprises a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis; wherein the first work member comprises a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis of the frame; and wherein the second work member comprises a substantially horizontal pivot axis disposed near the midpoint of longitudinal axis of the frame.

16. The work machine of claim 15 wherein the pivot axis of the control station, the pivot axis of the first work member, and the pivot axis of the second work member are disposed in relation to each other to create a close-coupled work machine.

17. The work machine of claim 16 wherein the pivot axis of the first work member and the pivot axis of the second work member substantially overlap.

18. The work machine of claim 1 wherein the first work member comprises: a swing arm pivotally connected to the frame; a swing post pivotally connected to the swing arm; a work tool supported by the swing post; and an unobstructed line of sight extending from the control station to the work tool of the first work member.

19. An excavator comprising: a frame having a first end and a second end; a control station supported by the frame; a low-profile power source supported by the frame; a first work member supported by the frame so that the first work member is operable at the first end of the frame and operated by the control station; a second work member supported by the frame so that the second work member is operable at the second end of the frame and operated by the control station, the second work member comprising: a lift arm having a first end and a second end, the first end being pivotally connected to the frame, and the second end being movable in a range of motion comprising a lower position and an upper position; a work tool supported by the second end of the lift arm; a first unobstructed line of sight extending from the control station over the low-profile power source to the work tool when the second end of the lift arm is in the lower position; and a second unobstructed line of sight extending from the control station to beyond the work tool when the second end of the lift arm is in the upper position.

20-21. (canceled)

22. The excavator of claim 19 wherein the control station is movable between at least a first position and a second position and adapted to control the first work member when in the first position and to control the second work member when in the second position.

23. The excavator of claim 22 wherein the control station comprises a plurality of controls operatively supported on the control station, the controls being adapted to control operation of the first work member and the second work member.

24-25. (canceled)

26. The excavator of claim 19 further comprising a low-profile left drive system and a low-profile right drive system both systems being supported by the frame for propelling the frame in a plurality of directions.

27-28. (canceled)

29. The excavator of claim 26 wherein the first work member comprises: a swing arm pivotally connected to the frame, the swing arm having a central longitudinal axis; a swing post pivotally connected to the swing arm; a swing arm actuator fixed to the frame and adapted to pivot the swing arm and swing post relative to the frame to a plurality of positions, the plurality of positions including at least one position placing the swing post beyond the left drive system, and at least one position placing the swing post beyond the right drive system; and a swing post actuator fixed to the swing arm and adapted to impart a pivot motion to the swing post relative to the swing arm to either side of the central longitudinal axis of the swing arm such that the pivot motion of the swing post is not restricted by the position of the swing arm.

30. The excavator of claim 19 wherein the frame comprises a longitudinal axis comprising a midpoint; wherein the pivotal control station comprises a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis; wherein the first work member comprises a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis of the frame; and wherein the second work member comprises a substantially horizontal pivot axis disposed near the midpoint of the longitudinal axis of the frame.

31. The excavator of claim 30 wherein the pivot axis of the control station, the pivot axis of the first work member, and the pivot axis of the second work member are disposed in relation to each other to create a close-coupled work machine.

32. (canceled)

33. The excavator of claim 19 wherein the first work member comprises: a swing arm pivotally connected to the frame; a swing post pivotally connected to the swing arm; a work tool supported by the swing post; and an unobstructed line of sight extending from the control station to the work tool of the first work member.

34. An excavator comprising: a frame comprising a first end and a second end; a low-profile left drive system and a low-profile right drive system both supported by the frame for propelling the frame in a plurality of directions; a first work member supported by the frame so that the first work member is operable at the first end of the frame, the first work member comprising: a swing arm pivotally connected to the frame and having a central longitudinal axis; a swing post pivotally connected to the swing arm; a swing arm actuator fixed to the frame and adapted to pivot the swing arm and swing post relative to the frame to a plurality of positions, the plurality positions including at least one position placing the swing post beyond the left drive system and at least one position placing the swing post beyond the right drive system; and a swing post actuator fixed to the swing arm and adapted to impart a pivot motion to the swing post relative to the swing arm to either side of the central longitudinal axis of the swing arm such that the pivot motion of the swing post is not restricted by the position of the swing arm; and a second work member supported by the frame so that the second work member is operable at the second end of the frame.

35. The excavator of claim 34 wherein the first work member comprises a work tool operatively connected to the swing post.

36. The excavator of claim 35 wherein the work tool comprises: a boom connected to the swing post; a dipper connected to the boom; and an excavating bucket connected to the dipper.

37. The excavator of claim 34 further comprising a pivotal control station supported by the frame and movable between at least a first position and a second position and adapted to control the first work member when in the first position and to control the second work member when in the second position.

38. The excavator of claim 37 wherein the pivotal control station comprises a plurality of controls supported on the control station, the controls being adapted to control operation of the first work member and the second work member.

39-47. (canceled)

48. The excavator of claim 34 further comprising: a work tool supported by the swing post; and an unobstructed line of sight extending from the control station to the work tool of the first work member.

49. A work machine comprising: a frame having a first end, a second end and a longitudinal axis comprising a midpoint; a pivotal control station supported by the frame and having a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis; a pivotal first work member supported by the frame having a substantially vertical pivot axis disposed near the midpoint of the longitudinal axis of the frame; and a pivotal second work member supported by the frame having a substantially horizontal pivot axis.

50. The work machine of claim 49 wherein the pivotal control station is movable between a first position and a second position and adapted to control the first work member when in the first work position and to control the second work member when in the second work position.

51. The work machine of claim 49 wherein the pivotal control station comprises a plurality of controls supported on the control station, the controls being adapted to control operation of the first work member and the second work member.

52-55. (canceled)

56. The work machine of claim 49 further comprising a low-profile power source supported by the frame.

57. The work machine of claim 56 wherein the second work member comprises: a lift arm having a first end and a second end, the first end being pivotally connected to the frame, and the second end being movable in a range of motion comprising a lower position and an upper position; and a work tool supported by the second end of the lift arm.

58. (canceled)

59. The work machine of claim 57 further comprising: a first unobstructed line of sight extending from the control station over the low-profile power source to the work tool when the second end of the lift arm is in the lower position; and a second unobstructed line of sight extending from the control station to beyond the work tool when the second end of the lift arm is in the upper position.

60. The work machine of claim 49 further comprising a low-profile left drive system and a low-profile right drive system, both systems being supported by the frame for propelling the frame in a plurality of directions.

61. The work machine of claim 60 wherein the first work member comprises: a swing arm pivotally connected to the frame, the swing arm having a central longitudinal axis; a swing post pivotally connected to the swing arm; a swing arm actuator fixed to the frame and adapted to pivot the swing arm and swing post relative to the frame to a plurality of positions, the plurality of positions including at least one position placing the swing post beyond the left drive system, and at least one position placing the swing post beyond the right drive system; and a swing post actuator fixed to the swing arm and adapted to impart a pivot motion to the swing post relative to the swing arm to either side of the central longitudinal axis of the swing arm such that the pivot motion of the swing post is not restricted by the position of the swing arm.

62. The work machine of claim 49 wherein the pivot axis of the control station, the pivot axis of the first work member, and the pivot axis of the second work member are disposed in relation to each other to create a close-coupled work machine.

63. The work machine of claim 49 wherein the first work member comprises: a swing arm pivotally connected to the frame; a swing post pivotally connected to the swing arm; a work tool supported by the swing post; and an unobstructed line of sight extending from the control station to the work tool of the first work member.

64. (canceled)

65. An excavator comprising: a frame having a first end and a second end; a pivotal control station supported by the frame; a first work member supported by the frame so that the first work member is operable at the first end of the frame, the first work member comprising; a swing arm pivotally connected to the frame; a swing post pivotally connected to the swing arm; and a work tool supported by the swing post; a second work member supported by the frame so that the second work member is operable at the second end of the frame; an unobstructed line of sight extending from the control station to the work tool of the first work member.

66. The excavator of claim 65 wherein the pivotal control station is movable between at least a first position and a second position and adapted to control the first work member when in the first work position and to control the second work member when in the second work position.

67. The excavator of claim 65 wherein the pivotal control station comprises a plurality of controls supported on the control station, the controls being adapted to control operation of the first work member and the second work member.

68. (canceled)

69. The excavator of claim 65 further comprising a low-profile power source supported by the frame.

70. The excavator of claim 69 wherein the second work member comprises: a lift arm having a first end and a second end, the first end being pivotally connected to the frame, and the second end being movable in a range of motion comprising a lower position and an upper position; and a work tool supported by the second end of the lift arm.

71. The excavator of claim 70 further comprising: a first unobstructed line of sight extending from the control station over the low-profile power source to the work tool when the second end of the lift arm is in the lower position; and a second unobstructed line of sight extending from the control station to beyond the work tool when the second end of the lift arm is in the upper position.

72. The excavator of claim 65 wherein the pivot axis of the control station, the pivot axis of the first work member, and the pivot axis of the second work member are disposed in relation to each other to create a close-coupled work machine.

73. A work machine comprising: a frame having a first end and a second end; a pivotal control station supported by the frame and having a substantially vertical pivot axis; a pivotal first work member supported by the frame so that the first work member is operable at the first end of the frame and the first work member comprising a substantially vertical pivot axis; a pivotal second work member supported by the frame so that the second work member is operable at the second end of the frame and comprises a substantially horizontal pivot axis; wherein the pivot axis of the control station, the pivot axis of the first work member, and the pivot axis of the second work member are disposed in relation to the frame to create a close-coupled work machine.

74. The work machine of claim 73 wherein the pivotal control station is movable between at least a first work position and a second work position and adapted to control the first work member when in the first work position and to control the second work member when in the second work position.

75-76. (canceled)

77. The work machine of claim 73 further comprising a low-profile left drive system and a low-profile right drive system, both systems being supported by the frame for propelling the frame in a plurality of directions.

78. The work machine of claim 77 wherein the first work member comprises: a swing arm pivotally connected to the frame, the swing arm having a central longitudinal axis; a swing post pivotally connected to the swing arm; a swing arm actuator fixed to the frame and adapted to pivot the swing arm and swing post relative to the frame to a plurality of positions, the plurality of positions including at least one position placing the swing post beyond the left drive system, and at least one position placing the swing post beyond the right drive system; and a swing post actuator fixed to the swing arm and adapted to impart a pivot motion to the swing post relative to the swing arm to either side of the central longitudinal axis of the swing arm such that the pivot motion of the swing post is not restricted by the position of the swing arm.

79-80. (canceled)