CABLESS LOADER LIFT ARM

Abstract

A lift arm has a longitudinal lift arm center line that is in a common plane with a longitudinal power machine center line. The lift arm is configured to rotate about a pivot axis that is perpendicular to the plane. The power machine includes a frame having an undercarriage and an upper portion, the undercarriage having opposed sides and the upper portion having a first width. The lift arm includes first and second cross members and a first elongated member. The first cross member spans the first width and is configured for attachment to the power machine at first and second joints. A first end of the first elongated member is attached to the first cross member inward of the opposed sides of the undercarriage. The second cross member is attached to the second end of the first elongated member and is configured for attachment to an implement.

Description

BACKGROUND

This disclosure is directed toward power machines. Power machines, for the purposes of this disclosure, include any type of machine that generates power to accomplish a particular task or a variety of tasks. One type of power machine is a work vehicle. Work vehicles are generally self-propelled vehicles that have a work device, such as a lift arm (although some work vehicles can have other work devices) that can be manipulated to perform a work function. Work vehicles include excavators, loaders, utility vehicles, tractors, and trenchers, to name a few examples.

Typically, power machines include a lift arm structure pivotally mounted to the frame of the power machine, with one or more lift actuators coupled between the frame and the lift arm structure to raise and lower the lift arm structure during work operations. For example, the lift arm structure can be used to raise and lower a bucket to move material. The design of the lift arm structure impacts important power machine characteristics, such as lift capacity, manufacturability, maintenance, durability, and cost.

The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.

SUMMARY

In one aspect, a lift arm is configured for attachment to a power machine at first and second joints. A longitudinal lift arm center line is in a common plane with a longitudinal power machine center line. The lift arm is configured to rotate about a pivot axis of the first and second joints that is perpendicular to the plane. The power machine includes a frame having an undercarriage and an upper portion, the undercarriage having opposed sides and the upper portion having a first width perpendicular to the center line. The lift arm comprises a first cross member, a first elongated member and a second cross member. The first cross member spans the first width and is configured for attachment to the frame at the first and second joints. The first elongated member has a first end and an opposed second end, wherein the first end of the first elongated member is attached to the first cross member inward of the opposed sides of the undercarriage. The second cross member is attached to the second end of the first elongated member, wherein the second cross member is configured for attachment to an implement.

In another aspect, a power machine has a longitudinal center line and comprises a frame, a lift arm, a front axle, a rear axle and a first actuator. The frame has a front end and a rear end, a first width between opposed left and right sides of an upper frame portion, and a second width between opposed left and right sides of an undercarriage. The lift arm has a front end and a rear end, wherein the rear end of the lift arm is attached to the frame proximate the left and right sides. The front axle is attached to the frame and configured for mounting a first tractive element. The rear axle is attached to the frame and configured for mounting a second tractive element. The first actuator is attached to the lift arm at a first joint and attached to the frame at a second joint, wherein the second joint is positioned forward of the front axle.

In yet another aspect, a lift arm has a first end and a second end and is configured for attachment to a power machine. The lift arm comprises a first cross member, first and second elongated members, and a second cross member. The first cross member comprises a first cross brace and first left and right lateral branches. The first left lateral branch extends from a left side of the first cross brace and terminates at a left rear joint at the first end. The first right lateral branch extends from a right side of the first cross brace and terminates at a right rear joint at the first end. The first elongated member is attached to the first cross member at a juncture of the first cross brace and the first left lateral branch. The second elongated member is attached to the first cross member at a juncture of the first cross brace and the first right lateral branch, and the second elongated member is parallel to the first elongated member. The second cross member comprises a second cross brace and second left and right lateral branches. The second left lateral branch extends from a left side of the second cross brace and terminates at a left front joint at the second end. The second right lateral branch extends from a right side of the second cross brace and terminates at a right front joint at the second end.

This summary and the Abstract are provided to introduce concepts in simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the disclosed or claimed subject matter and is not intended to describe each disclosed embodiment or every implementation of the disclosed or claimed subject matter. Specifically, features disclosed herein with respect to one embodiment may be equally applicable to another. Further, this summary is not intended to be used as an aid in determining the scope of the claimed subject matter. Many other novel advantages, features, and relationships will become apparent as this description proceeds. The figures and the description that follow more particularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed subject matter will be further explained with reference to the attached figures, wherein like structure or system elements are referred to by like reference numerals throughout the several views. All descriptions are applicable to like and analogous structures throughout the several embodiments, unless otherwise specified.

FIG. 1 is a perspective view of a power machine with an exemplary lift arm.

FIG. 2 is a top view of the power machine.

FIG. 3 is a left side sectional view of the power machine, taken through line 3-3 of FIG. 1.

FIG. 4 is a left perspective view of a frame of the machine with the exemplary lift arm.

FIG. 5 is an enlarged partial left perspective view of the power machine, showing a stop contact between the lift arm and the machine frame.

FIG. 6 is a top perspective view of the lift arm removed from the machine frame and actuators.

FIG. 7 is a bottom perspective view of the lift arm of FIG. 6.

FIG. 8 is a rear perspective view of the power machine with an exemplary implement mounted on the implement carrier, wherein the lift arm is lowered and the implement is level.

FIG. 9 is a side elevation view of the power machine in the configuration of FIG. 8.

FIG. 10 is a side elevation view of the power machine, showing the lift arm in a lowered position and the implement in a “roll in” configuration compared to FIG. 9.

FIG. 11 is a side elevation view of a power machine with the lift arm in an intermediate raised position and the implement rolled out to a “doze” position.

FIG. 12 is a rear perspective view of the power machine in the configuration of FIG. 11.

FIG. 13 is a side elevation view of a power machine with the lift arm in a fully raised position and the implement in a substantially level position.

FIG. 14 is a rear perspective view of the power machine in the configuration of FIG. 13.

FIG. 15 is a side elevation view of the power machine with the lift arm in a fully raised position and the implement in a “roll in” position compared to FIG. 13.

FIG. 16 is a rear perspective view of the power machine in the configuration of FIG. 15.

FIG. 17 is a side elevation view of a power machine with the lift arm in a fully raised position and the implement in a “roll out” position compared to FIG. 13.

FIG. 18 is a rear perspective view of the power machine in the configuration of FIG. 17.

While the above-identified figures set forth one or more embodiments of the disclosed subject matter, other embodiments are also contemplated, as noted in the disclosure. In all cases, this disclosure presents the disclosed subject matter by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that fall within the scope of the principles of this disclosure.

The figures may not be drawn to scale. In particular, some features may be enlarged relative to other features for clarity. Moreover, where terms such as above, below, over, under, top, bottom, side, right, left, vertical, horizontal, etc., are used, it is to be understood that they are used only for ease of understanding the description. It is contemplated that structures may be oriented otherwise.

The terminology used herein is for the purpose of describing embodiments, and the terminology is not intended to be limiting. Unless indicated otherwise, ordinal numbers (e.g., first, second, third, etc.) are used to distinguish or identify different elements or steps in a group of elements or steps and do not supply a serial or numerical limitation on the elements or steps of the embodiments thereof. For example, “first,” “second,” and “third” elements or steps need not necessarily appear in that order, and the embodiments thereof need not necessarily be limited to three elements or steps. Unless indicated otherwise, any labels such as “left,” “right,” “front,” “back,” “top,” “bottom,” “forward,” “reverse,” “clockwise,” “counter clockwise,” “up,” “down,” or other similar terms such as “upper,” “lower,” “aft,” “fore,” “vertical,” “horizontal,” “proximal,” “distal,” “intermediate” and the like are used for convenience and are not intended to imply, for example, any particular fixed location, orientation, or direction. Instead, such labels are used to reflect, for example, relative location, orientation, or directions. The singular forms of “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

DETAILED DESCRIPTION

The concepts disclosed in this discussion are described and illustrated with reference to exemplary embodiments. These concepts, however, are not limited in their application to the details of construction and the arrangement of components in the illustrative embodiments and are capable of being practiced or being carried out in various other ways. The terminology in this document is used for description and should not be regarded as limiting. Words such as “including,” “comprising,” and “having” and variations thereof as used herein are meant to encompass the items listed thereafter, equivalents thereof, as well as additional items.

A representative power machine on which the lift arm embodiments can be practiced is illustrated in FIG. 1. For the sake of brevity, only one power machine is discussed. However, the disclosed teachings can be practiced on any of a number of power machines, including power machines of different types from the representative, illustrated power machine. Power machines, for the purposes of this discussion, include a frame, at least one work element, and a power source that can provide power to the work element to accomplish a work task. One type of power machine is a self-propelled work vehicle. At least one of the work elements is a motive system for moving the power machine under power.

FIG. 1 shows a power machine 100 upon which the lift arm embodiments discussed herein can be advantageously incorporated and can be any of several distinct types of power machines. The power machine 100 has a frame 110, a power source 120, and a work element, such as a lift arm 130. Because power machine 100 shown in FIG. 1 is a self-propelled work vehicle, it also has tractive elements 140, which are themselves work elements provided to move the power machine over a support surface. Tractive elements can be, for example, wheels attached to an axle, track assemblies, and the like. Tractive elements can be rigidly mounted to the frame such that movement of the tractive element is limited to rotation about an axle or steerably mounted to the frame to accomplish steering by pivoting the tractive element with respect to the frame.

Work elements of the power machine 100 can be operated from an operator station 150, shown schematically as being remotely connected to control system 160. A human operator can control operation of machine 100 through remote, wireless controls or operation of machine 100 can be autonomous. In another embodiment, an operator station positioned on or near machine 100 can provide an operating position for a human. A control system 160, shown schematically, is provided to interact with the other systems to perform various work tasks at least in part in response to control signals provided by an operator or autonomous controller.

Certain work vehicles have work elements that can perform a dedicated task. For example, some work vehicles have a lift arm 130 to which an implement 180 (shown in FIG. 8) such as a bucket is attached. A work element such as a lift arm 130 can be manipulated to position the implement 180 for performing the task. The implement 180 in some instances can be positioned relative to the work element, such as by tilting a bucket relative to a lift arm, to further position the implement. Under normal operation of such a work vehicle, the bucket is intended to be attached and under use. Such work vehicles may be able to accept other implements by disassembling the implement/work element combination and reassembling another implement in place of the original bucket. Some work vehicles are intended to be used with a wide variety of implements and have an implement interface. At its most basic, an implement interface is a connection mechanism between the frame 110 or a lift arm 130 and an implement 180, which can be as simple as a connection point for attaching an implement directly to the frame 110 or lift arm 130 or more complex, as discussed below.

In an exemplary embodiment, implement interface 170 also includes an implement power source available for connection to an implement on the lift arm 130. The implement power source can include pressurized hydraulic fluid ports or electrical ports or a power take-off to which an implement can be coupled. For example, an electrical power source can be provided for powering electrical actuators and/or an electronic controller on an implement 180. An electrical power source can also include electrical conduits that are in communication with a data bus on the machine 100 to allow communication between a controller on an implement and electronic devices on the machine 100.

On some power machines, implement interface 170 can include an implement carrier, which is a physical structure movably attached to a work element 130. The implement carrier has engagement features and locking features to accept and secure any of several implements to the work element. One characteristic of such an implement carrier is that once an implement is attached to it, it is fixed to the implement (i.e., not movable with respect to the implement) and when the implement carrier is moved with respect to the work element, the implement moves with the implement carrier. The term “implement carrier” is not merely a pivotal connection point, but rather a dedicated device specifically intended to accept and be secured to various different implements. As illustrated, implement interface 170 in the form of an implement carrier is mountable to lift arm 130 at pivot joints 242. Additionally, implement interface 170 is pivotally attached to tilt actuator 202 at pivot 258. Some power machines can have a plurality of work elements with implement interfaces, each of which may, but need not, have an implement carrier for receiving implements. Some other power machines can have a work element with a plurality of implement interfaces so that a single work element can accept a plurality of implements simultaneously. Each of these implement interfaces can, but need not, have an implement carrier.

Frame 110 includes a physical structure that can support various other components that are attached thereto or positioned thereon. The frame 110 can include any number of individual components. Some power machines have frames that are rigid. That is, no part of the frame is movable with respect to another part of the frame. Other power machines have at least one portion that can move with respect to another portion of the frame. For example, excavators can have an upper frame portion that rotates about a swivel with respect to a lower frame portion. Other work vehicles have articulated frames such that one portion of the frame pivots with respect to another portion for accomplishing steering functions.

Frame 110 supports the power source 120, which can provide power to work elements including the lift arm 130 and one or more tractive elements 140, as well as, in some instances, providing power for use by an attached implement 180 via implement interface 170. Additionally or alternatively, power from the power source 120 can be provided to a control system 160, which in turn selectively provides power to the elements that are capable of using it to perform a work function. Power sources for power machines frequently include an electric battery, an engine such as an internal combustion engine and/or a power conversion system such as a mechanical transmission or a hydraulic system that can convert the output from an engine into a form of power that is usable by a work element. Other types of power sources can be incorporated into power machines, including electrical sources or a combination of power sources, known generally as hybrid power sources.

In an exemplary embodiment, power machine 100 is configured as a cabless loader, such that the operator station 150 is remote from the machine 100. A remote-control device can be provided (i.e., remote from both of the power machine and any implement to which is it coupled) that can control at least some of the operator-controlled functions on the power machine. Power machine 100 can also be autonomously controlled. The illustrated power machine 100 should not be considered limiting, especially as to features that are not essential to use of the disclosed embodiments of a lift arm 130. Unless specifically noted otherwise, embodiments of lift arm 130 disclosed below can be practiced on a variety of power machines, with the illustrated loader being only one of those power machines.

In an exemplary embodiment, machine 100 includes frame 110. The frame 110 supports a power source 120, the power source 120 being configured to generate or otherwise provide power for operating various functions on the power machine. The frame 110 also supports a work element in the form of a lift arm 130 to which actuators 200, 202 are connected. In an exemplary embodiment, actuator 200 is a lift actuator; in its retracted state, the lift arm 130 is in a lowered position, as shown in FIGS. 8-10, for example. With an intermediate extension configuration of lift actuator 200, the lift arm 130 is in an intermediately raised position, as shown in FIGS. 11 and 12. In a fully extended configuration of lift actuator 200, the lift arm 130 is in a fully raised position, as shown in FIGS. 13-18. In an exemplary embodiment, actuator 202 is a tilt actuator. In a retracted configuration of tilt actuator 202, the implement 180 is in a “roll in” position relative to lift arm 130, as shown in FIGS. 15 and 16, for example. With intermediate extension of tilt actuator 202, and depending upon the position of lift arm 130, the implement 180 can assume a level configuration with a raised lift arm 130, as shown in FIGS. 13 and 14, for example. With full extension of tilt actuator 202, and depending upon a position of lift arm 130, the implement 180 can assume a “roll out” position relative to the lift arm 130, as shown in FIGS. 17 and 18, for example. Each extendable actuator 200, 202 is configured with a rod 215 that is selectively extendable and retractable relative to a surrounding cylinder base 214 (labeled in FIG. 13).

In exemplary embodiments, actuators 200, 202 are extendable cylinders that can be, for example, hydraulic cylinders, pneumatic cylinders, or electric cylinders, or powered by some other mechanism. Actuators 200, 202 can also be other types of electric or other actuators, and need not be cylinders in all embodiments. In the illustrated embodiment, each of actuators 200, 202 is an electric actuator powered by a respective electric motor 204, 206. In an exemplary embodiment, each of the actuator motors 204, 206 is selectively powered by the power source 120 in the form of an electric battery in response to signals from control system 160.

The elements of frame 110 discussed herein are provided for illustrative purposes and are not necessarily the only type of frame that a power machine on which the lift arm embodiments can be practiced or employed. The frame 110 of the machine 100 includes an undercarriage or lower portion 210 and an upper portion 212 that is supported by the undercarriage 210. The upper frame 212 of the machine 100 is attached to the undercarriage 210 such as with fasteners or by welding. The upper frame 212 includes a pair of upright portions located on opposed sides and toward the rear of frame 110, to which the lift arm 130 is pivotally attached.

In an exemplary embodiment, the undercarriage 210 is configured with a central cavity between inner walls 243 of chain case housings 244 to support a power source 120 in the form of an electric battery. In an exemplary embodiment, two side portions of the undercarriage 210 encase the drive chains for tractive elements 140 in the form of wheels, wherein a sprocket on each axle is turned by chains for a skid-steer type of tractive control. In an exemplary embodiment, drive motors for the tractive drive are contained between the two uprights of the upper frame portion 212 and behind the power source 120.

In the illustrated embodiments, the lift arm 130 is pivotally connected to each of the upright portions of upper frame 212. However, the lift arm 130 could also be indirectly connected to the frame 212, such as by linkages and/or drivers and followers to allow for a vertical lift path, for example. The combination of mounting features on the upper frame 212 and the lift arm 130 and mounting hardware (including pins, linkages, drivers, followers or other components used to attach the lift arm structure to the upper frame 212) are collectively referred to as joints 216 (one is located on each of the upright portions) for the purposes of this discussion. In an exemplary embodiment, the joints 216 are aligned along an axis 218 so that the lift arm structure is capable of pivoting, as shown in FIGS. 8-18, about axis 218 of pivot joint 216.

FIGS. 6 and 7 show top and bottom perspective views, respectively, of a lift arm 130 in isolation, removed from the power machine 100 and the actuators 200, 202 that would be attached to the lift arm 130 for use of the machine 100. In an exemplary embodiment, lift arm 130 has a general X-shape viewed from the top or bottom, with a narrowed central portion at elongated members 230. The central portion is attached at one end to a generally V-shaped upper cross member 220, which extends at an angle directed laterally outward from the central portion as well as longitudinally; the upper cross member 220 includes an upper cross brace 228 located on the center line C, from which lateral branches 238 extend outwardly and lengthwise to joints 216. The central portion is attached at its opposite end to a generally V-shaped lower cross member 232, which extends at an angle directed laterally outward from the central portion as well as longitudinally; the lower cross member 232 includes a lower cross brace 234 located on the center line C, from which lateral branches 240 extend outwardly and lengthwise to pivot joints 242; top wall 231 and front wall 233 extend between the lateral branches 240. As shown in FIG. 2, the central portion of lift arm 130 at elongated members 230 is positioned well inboard or inward of the left and right sides of undercarriage 210 and proximate center line C. In an exemplary embodiment, a lateral distance, as seen in FIG. 2 parallel to axis 218, between each elongated member 230 to center line C is less than a lateral distance of that elongated member to a nearest side edge of undercarriage 210. Moreover, in an exemplary embodiment, each elongated member 230 is positioned well inboard or inward of the inner walls 243 of the chain case housings 244. Additionally, in an exemplary embodiment, in a direction parallel to axis 218, each elongated member 230 is positioned about mid-way between center line C and a nearest chain case housing inner wall 243.

In an exemplary embodiment, upper cross member 220 spans laterally between joints 216 and forward of the upright portions of upper frame 212. The components of lift arm 130 shown in FIGS. 6 and 7 are fixed relative to each other. However, referring to FIG. 3, for example, the lift actuator 200 is configured to pivotally connect to the lift arm 130 at a bushing at joint 222. A bushing brace 224 and side plates 226 are referred to as an upper cross brace 228 (cross braces 228, 234 may also be referred to as pivot columns). In an exemplary embodiment, upper cross brace 228 is positioned on a center line C of upper cross member 220, as labeled in FIG. 2. As shown in FIG. 2, the center lines C of both the frame 110 and the lift arm 130 are coincident and lie in a common plane. A pair of elongated members 230 connect the upper cross member 220 to lower cross member 232. In an exemplary embodiment, lower cross brace 234 includes a bushing at pivot joint 236 (for an end of tilt actuator 202), side plates 226, and bushing brace 224. Elongated members 230 are closely spaced together near center line C; in an exemplary embodiment, the two elongated members are spaced apart only enough to provide clearance at each of cross braces 228, 234 for their respectively pivot bushings.

In an exemplary embodiment, upper cross member 220 includes lateral branches 238 that extend outwardly from the upper cross brace 228 to joints 216. Similarly, lateral branches 240 of lower cross member 232 extend from the centrally positioned lower cross brace 234 outward to implement joints 242. In an exemplary embodiment, each lateral branch 238, 240 terminates in a pivot casting for joint 216 or joint 242, respectively. In an exemplary embodiment, a pivot casting for each joint 216, 242 extends between an inner wall 246 and an outer wall 248 at the terminus of each lateral branch 238, 240. In an exemplary embodiment, end cross member or cross tube 250 spans between the inner walls 246 of lower cross member 232 proximate the implement joints 242. Referring to FIGS. 3 and 9, in an exemplary embodiment, implement interface 170 is attachable to lift arm 130 at implement joints 242. End cross member 250 provides increased structural stability to the lift arm 130. In an exemplary embodiment, each lateral branch 238, 240 also has top and bottom walls extending between inner angled wall 252 and outer angled wall 254.

As shown in FIGS. 6 and 7, inner angled wall 252 extends from inner wall 246 toward elongated member 230. Similarly, outer angled wall 254 extends from outer wall 248 toward elongated member 230. In an exemplary embodiment, each of the elongated members 230 is positioned proximate the lift actuator 200 and far inward of the lateral left and right sides of the upper frame 212 and undercarriage 210 of machine 100, as shown in FIG. 2, for example. Thus, while lift arm 130 has widely spaced attachment points for its attachment to upper frame 212 at joints 216, and widely spaced attachment joints 242 for an implement 180 or implement carrier 170, the elongated members 230 concentrate structure near a longitudinal centerline C of the machine 100, thereby providing for a robust lift arm that is well balanced on the machine, absorbs twisting forces, and prevents lateral tilting of the machine even when the implement 180 carries an unbalanced load. While elongated member 230 is illustrated as a tube with a substantially rectangular cross section, any elongated structure could be used, such as an inverted U-channel, for example. Telescoping structures can also be used for elongated members 230 to allow for length extension of the lift arm 130, for example. In an exemplary embodiment, the elongated members 230 are provided close to the lift actuator 200 and on opposed sides thereof to counteract twisting loads and torque forces caused by the manipulation of an implement 180 against a material surface or in transport of a material load. While the illustrations show two elongated members 230, it is also possible for lift arm 130 to have a single elongated member that connects upper cross member 220 and lower cross member 232 (such as a single inverted U-channel elongated member, for example).

FIGS. 3 and 13 show that in an exemplary embodiment, a cylinder base 214 of lift actuator 200 is pivotally attached to upper cross brace 228 at a bushing located at joint 222. A rod 215 of lift actuator 200 is pivotally attached to undercarriage 210 at joint 256. In an exemplary embodiment, a cylinder base 214 of tilt cylinder 202 is pivotally attached to lower cross brace 234 at joint 236, and a rod 215 of tilt cylinder 202 is pivotally attached at joint 258 to implement carrier 170.

As shown in FIGS. 3 and 4, for example, motor 204 is attached to lift actuator 200 at a top of the cylinder base and proximate joint 222. Motor 206 is attached to tilt actuator 202 near a top of the cylinder base and proximate joint 236. Moreover, each of the motors 204, 206 is positioned under its respective actuator 200, 202 to provide an unencumbered exterior top presentation of the lift arm 130 that is able to easily shed dirt and debris. Moreover, as shown in FIG. 4, this positioning of the motors 204, 206 allows ample space in the undercarriage 210 for the power source 120 and other components (no power source is shown in FIG. 3). In an exemplary embodiment, tilt actuator 202 is operably coupled to the lift arm 130 at its cylinder base joint 236 and to implement interface 170 at its rod pivot joint 258. However, it is to be understood that the lift and tilt actuators could be inverted so that the cylinder base and rod are at opposite ends than illustrated.

A forward direction F is labeled in FIGS. 1-3, in which the arrow points in the direction of a front of the machine 100. In an exemplary embodiment, lift actuator 200 is joined at its top end to lift arm 130 at joint 222; joint 222 is positioned forward of rear axle 260. In an exemplary embodiment, lift actuator 200 is joined at its bottom end to undercarriage 210 at joint 256; joint 256 is positioned forward of front axle 262. The relatively forward placement of the lift actuator 200 balances weight of the machine 100. Moreover, positioning of the forward end of lift arm 130 at joint 256 forward of the front axle 262 allows ample space in the undercarriage 210 for the power source 120 and other components.

The width of lift arm 130 at joints 216 of upper cross member 220 and at joints 242 of lower cross member 232 contribute to rigidity of the lift arm 130 and its distribution of forces to frame 110. The front end of lift arm 130 proximate end cross member 250 is moveable to lift off frame 110 in a radial path about axis 218 or a vertical lift path. In the fully lowered position of lift arm 130 shown in FIGS. 1-5 and 8-10, contact pads 263 of lift arm 130 are configured to rest upon stop pads 264 of undercarriage 210 (labeled in FIGS. 4 and 5). Thus, the weight of lift arm 130, implement carrier 170, implement 180, and any material carried by the implement 180 is supported not only by the lift arm 130; the load forces are also transmitted to and distributed across the frame 110 of the machine 100.

In an exemplary embodiment, joint 216 is positioned rearward of the rear axle 260. This unexpected position allows for a wide radial arc of motion of the load arm 130 on a short machine 100 because there is no cab in which, or on which, an operator is positioned. Because an operator controls an exemplary embodiment of the disclosed machine 100 remotely, or the machine is controlled autonomously, the structures of machine 100 can be positioned in locations that might not work in a machine having an operator cab. In such machines with a cab, considerations should be made for the operator's visibility of the position and content of the implement 180 at the end of the lift arm 130.

FIG. 9 is a side elevation view of an exemplary machine 100 with an implement 180 attached to its implement interface 170. In the illustrated embodiment, implement 180 is configured as a loader bucket and is shown in a level position in FIG. 9, wherein a bottom surface 266 of implement 180 is substantially parallel to a ground surface upon which the machine 100 rests or traverses. In an exemplary embodiment, implement 180 has an open side 268 into which material can be deposited.

FIG. 10 is a side elevation view of an exemplary power machine 100, wherein the tilt actuator 202 is shortened (such as by retracting its rod 215 into its cylinder base 214) compared to the configuration of FIG. 9 so that the implement 180 is in a “roll in” position compared to its position in FIG. 9. In this position, material can be carried within the bucket of implement 180 without spilling out the open side 268.

FIGS. 11 and 12 show a configuration of power machine 100 in which the lift actuator 200 is partially extended to pivot lift arm 130 about joint 216 with frame 110, to thereby raise the implement end. Moreover, compared to the level implement position of FIG. 9, the tilt actuator is extended to rotate implement 180 about implement joint 242 to a “doze” position, wherein the bottom surface 266 is substantially perpendicular to a ground surface. Thus, forward motion of the machine 100 will push material out of the travel path of machine 100.

FIGS. 13 and 14 show lift actuator 200 in a fully extended position, thereby moving the implement end of lift arm 130 to its highest position. Extension of the tilt actuator 202 is intermediate between the positions shown in FIGS. 9 and 11, resulting in an approximately level position of the raised implement 180.

FIGS. 15 and 16 show relative positions of the lift arm 130 and the implement 180 when lift actuator 200 is fully extended and tilt actuator 202 is fully retracted (a “roll in” configuration of implement 180). FIGS. 17 and 18 show relative positions of lift arm 130 and implement 180 when lift actuator 200 is fully extended and tilt actuator 202 is fully extended (a “roll out” configuration of implement 180).

Exemplary, non-limiting embodiments of a lift arm and a power machine are described. In an exemplary embodiment, a lift arm 130 is configured for attachment to a power machine at first and second pivot joints 216, wherein a longitudinal lift arm center line C is in a common plane with a longitudinal power machine center line C. In an exemplary embodiment, the lift arm 130 is configured to rotate about a pivot axis 218 of the first and second pivot joints 216 that is perpendicular to the plane. In an exemplary embodiment, the power machine comprises a frame 110 and a plurality of tractive elements 140. In an exemplary embodiment, the frame 110 has opposed left and right sides, wherein the first and second pivot joints 216 are positioned proximate the opposed left and right sides of the frame 110. In an exemplary embodiment, a plurality of tractive elements 140 are attached to the frame 110 and configured to support the frame 110 on a surface. In an exemplary embodiment, the lift arm 130 comprises first cross member 220, second cross member 232, and a first elongated member 230. In an exemplary embodiment, the first cross member 220 is configured for attachment to the frame 110 at the first and second pivot joints 216. In an exemplary embodiment, the first elongated member 230 has a first end and an opposed second end, wherein the first end of the first elongated member 230 is attached to the first cross member 220 proximate the longitudinal lift arm center line C. In an exemplary embodiment, the second cross member 232 is attached to the second end of the first elongated member 230, wherein the second cross member 232 is configured for attachment to an implement 180.

In an exemplary embodiment, the first and second elongated members 230 are parallel to each other. In an exemplary embodiment, the first cross member 220 comprises a third pivot joint 222 positioned on the lift arm center line C and configured for attachment to a first actuator 200. In an exemplary embodiment, the second cross member 232 comprises a fourth pivot joint 236 positioned on the lift arm center line C and configured for attachment to a second actuator 202. In an exemplary embodiment, the second cross member 232 comprises first and second lateral branches 240 extending laterally from the lift arm center line C, wherein each of the first and second lateral branches 240 terminates proximate an implement joint 242. In an exemplary embodiment, a third cross member 250 spans between the first and second lateral branches 240 proximate the implement joints 242.

In an exemplary embodiment, the first cross member 220 comprises first and second lateral branches 238 extending laterally from the lift arm center line C. In an exemplary embodiment, the first lateral branch 238 terminates proximate the first pivot joint 216, and the second lateral branch 238 terminates proximate the second pivot joint 216. In an exemplary embodiment, the first cross member 220, the first elongated member 230, and the second cross member 232 are mutually positionally fixed, in contrast to moving parts of an articulated lift arm.

In an exemplary embodiment, a power machine 100 has a longitudinal center line C and comprises a frame 110, a lift arm 130, a front axle 262, a rear axle 260 and a first actuator 200. The frame has a front end, a rear end, and opposed left and right sides. The lift arm 130 has a front end and a rear end, wherein the rear end of the lift arm 130 is pivotally attached to the frame 110 proximate the left and right sides. The front axle 262 is attached to the frame 110 and configured for mounting a first tractive element 140. The rear axle 260 is attached to the frame 110 and configured for mounting a second tractive element 140. While the tractive elements 140 are illustrated with smooth tires for simplicity, it is to be understood that they can have deep treads for traction. The first actuator 200 is attached to the lift arm 130 at a first joint 222 and attached to the frame 110 at a second joint 256, wherein the second joint 256 is positioned forward of the front axle 262. In an exemplary embodiment, the lift arm 130 is pivotally attached to the frame at 216, rearward of the rear axle 260.

In an exemplary embodiment, the first actuator 200 comprises a cylinder 214 and an extendable rod 215, wherein the cylinder 214 is disposed proximate the first joint 222 and the rod 215 is disposed proximate the second joint 256. In an exemplary embodiment, an actuator motor 204 attached to the cylinder 214 along the longitudinal center line C. In an exemplary embodiment, the actuator motor 204 is disposed between the cylinder 214 and the frame 110. In an exemplary embodiment, a second actuator 202 is attached to the lift arm 130 at a third joint 236 and configured for attachment to an implement 180 at a fourth joint 242 (such as via implement interface 170). In an exemplary embodiment, the implement 180 is configured as a bucket.

In an exemplary embodiment, a power machine 100 has a longitudinal center line C and comprises a frame 110, a lift arm 130, a first actuator 200 and a second actuator 202. The frame 110 has a front end, a rear end, and opposed left and right sides. The lift arm 130 has a front end and a rear end, wherein the front and rear ends are positionally fixed relative to each other. The lift arm 130 is symmetrically aligned along the longitudinal center line C. The rear end of the lift arm 130 is pivotally attached to the frame proximate the left and right sides at first and second joints 216, respectively. The front end of the lift arm 130 is radially movable about the first and second joints 216 between a lowered position and a raised position. The first and second actuators 200, 202 are aligned along the longitudinal center line C. The first actuator 200 is attached to the lift 130 arm at a third joint 222 and attached to the frame 110 at a fourth joint 256. The first actuator 200 is configured to pivotally move the lift arm 130. The second actuator 202 is attached to the lift arm 130 at a fifth joint 236 and attached to an implement 180 (such as by implement interface 170) at a sixth joint 258. The second actuator 202 is configured to tilt the implement 180 with respect to the front end of the lift arm 130.

In an exemplary embodiment, a motor 206 is operatively connected to the second actuator 202. The motor 206 is aligned along the longitudinal center line C and disposed between the first actuator 200 and the second actuator 202 when the lift arm 130 is in the lowered position, such as depicted in FIG. 3, for example. In an exemplary embodiment, in the lowered position, the front end of lift arm 130 contacts the frame 110 proximate the left and right sides, such as depicted in FIGS. 4 and 5, for example. In an exemplary embodiment, in the raised position, the front end of the lift arm 130 is spaced from the frame 110, such as depicted in FIGS. 11-18, for example.

Although the subject of this disclosure has been described with reference to several embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the disclosure. In addition, any feature disclosed with respect to one embodiment may be included in another embodiment, and vice-versa.

Claims

1. A lift arm configured for attachment to a power machine at first and second joints, wherein a longitudinal lift arm center line is in a common plane with a longitudinal power machine center line, and wherein the lift arm is configured to rotate about a pivot axis of the first and second joints that is perpendicular to the plane, wherein the power machine includes a frame having an undercarriage and an upper portion, the undercarriage having two chain case housings with respective inner walls and the upper portion having a first width perpendicular to the center line, the lift arm comprising: a first cross member spanning the first width and configured for attachment to the frame at the first and second joints;a first elongated member having a first end and an opposed second end, wherein the first end of the first elongated member is attached to the first cross member inward of a respective inner wall of a respective chain case housing; anda second cross member attached to the second end of the first elongated member, wherein the second cross member is configured for attachment to an implement.

2. The lift arm of claim 1 comprising a second elongated member is that parallel to the first elongated member.

3. The lift arm of claim 1, wherein the first cross member comprises a third joint positioned on the lift arm center line and configured for attachment to a first actuator.

4. The lift arm of claim 3, wherein the first cross member comprises first and second lateral branches extending outwardly away from the third joint, wherein: the first lateral branch terminates proximate the first joint; andthe second lateral branch terminates proximate the second joint.

5. The lift arm of claim 3, wherein the second cross member comprises a fourth joint positioned on the lift arm center line and configured for attachment to a second actuator.

6. The lift arm of claim 5, wherein the second cross member comprises first and second lateral branches extending outwardly away from the fourth joint, and wherein each of the first and second lateral branches terminates proximate an implement joint.

7. The lift arm of claim 6 comprising a third cross member that spans between the first and second lateral branches proximate the implement joints.

8. The lift arm of claim 1, wherein the first cross member, the first elongated member, and the second cross member are mutually positionally fixed.

9. A power machine having a longitudinal center line and comprising: a frame having a front end and a rear end, a first width between opposed left and right sides of an upper frame portion, and a second width between opposed left and right sides of an undercarriage;a lift arm having a front end and a rear end, wherein the rear end of the lift arm is attached to the frame proximate the left and right sides;a front axle attached to the frame and configured for mounting a first tractive element;a rear axle attached to the frame and configured for mounting a second tractive element; anda first actuator attached to the lift arm at a first joint and attached to the frame at a second joint, wherein the second joint is positioned forward of the front axle.

10. The power machine of claim 9, wherein the lift arm comprises: a first cross member spanning the first width;a first elongated member having opposed first and second ends, wherein the first end is attached to the first cross member inward of the left and right sides of the undercarriage; anda second cross member attached to the second end of the first elongated member and spanning the second width.

11. The power machine of claim 10, wherein the first joint of the first actuator is positioned along the longitudinal center line of the power machine.

12. The power machine of claim 11, wherein the first elongated member is one of two parallel elongated members that are equally spaced from the longitudinal center line on opposed sides of the first joint.

13. The power machine of claim 9 comprising a second actuator attached to the lift arm at a third joint and configured for attachment to an implement at a fourth joint.

14. The power machine of claim 13 comprising the implement, wherein the implement is configured as a bucket.

15. The power machine of claim 9, wherein the lift arm is attached to the frame rearward of the rear axle.

16. A lift arm having a first end and a second end and configured for attachment to a power machine, the lift arm comprising: a first cross member comprising: a first cross brace;a first left lateral branch extending from a left side of the first cross brace and terminating at a left rear joint at the first end;a first right lateral branch extending from a right side of the first cross brace and terminating at a right rear joint at the first end;a first elongated member attached to the first cross member at a juncture of the first cross brace and the first left lateral branch;a second elongated member attached to the first cross member at a juncture of the first cross brace and the first right lateral branch, wherein the second elongated member is parallel to the first elongated member; anda second cross member comprising: a second cross brace;a second left lateral branch extending from a left side of the second cross brace and terminating at a left front joint at the second end; anda second right lateral branch extending from a right side of the second cross brace and terminating at a right front joint at the second end.

17. The lift arm of claim 16 comprising a third cross member that spans between the second left and right lateral branches proximate the left and right front joints.

18. The lift arm of claim 16, wherein each of the first and second elongated members is configured as a tube.

19. The lift arm of claim 16, wherein each of the first left and right lateral branches comprises an inner angled wall and an outer angled wall joined by top and bottom walls.

20. The lift arm of claim 16, wherein at least one of the first and second cross braces comprises two side plates joined by a bushing brace.