Patent Publication Number: US-2021178982-A1

Title: Display position for cab with overhead door

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 62/700,539, which was filed on Jul. 19, 2018. 
    
    
     BACKGROUND 
     The present disclosure is directed toward power machines. More particularly, the present disclosure is related to doors on and display panels in cabs of power machines. 
     Power machines, for the purposes of this disclosure, include any type of machine that generates power for accomplishing a particular task or a variety of tasks. One type of power machine is a work vehicle. Work vehicles, such as loaders, 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 loaders, excavators, utility vehicles, tractors, and trenchers, to name a few examples. 
     Many power machines have operator compartments defined, at least in part, by a cab in which an operator can sit while operating the power machine. Some of these cabs have doors that can be opened to allow access into and out of the cab and can be closed to provide protection from the elements and the like when an operator is located within the cab. Some loaders with front door entry have lift arms, at least parts of which move in front of the cab such that the door must be closed while operating the power machine otherwise the door, in the open position, will interfere with the travel path of the lift arm or more particularly, a cross-member that is coupled to lift arms located on each side of the power machine. A solution to this interference problem between the door and the lift arm can include a door that opens upwardly and sits above the operator&#39;s head when operated. Inside the cab are various operator controls and instrumentation, including a display. Having such a door could interfere with the display inside of the cab. 
     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 
     This Summary and the Abstract are provided to introduce a selection of concepts in a 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 claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     Disclosed are front entry cabs, and power machines with front entry cabs, having a door that is moveable between opened and closed positions and a display oriented in the cab to provide information to the operator both while the door is in the opened and closed positions. In the opened position, the door is positioned within an operator compartment of the cab above the operator seat and below a top of the cab. The display is positioned to not interfere with the door, door linkages, or operator joystick control. 
     In some exemplary embodiments, a cab ( 250 ;  350 ;  450 ;  550 ;  650 ) for a power machine ( 100 ;  200 ) includes a cab frame ( 210 ;  310 ) forming an operator compartment and having a first side wall ( 312 ), a second sidewall ( 314 ), a front ( 316 ), a rear ( 318 ), a top ( 320 ) and a bottom ( 323 ). An operator seat ( 364 ;  464 ;  564 ) is positioned within the cab. A cab door ( 324 ;  424 ;  524 ;  624 ) is configured to cover an opening ( 326 ) in the front of the cab frame when in a closed position and to be moved between the closed position and an open position overhead of the operator seat. A display ( 302 ;  402 ) is mounted to a pillar ( 382 ) of the cab frame in a corner between the front and one of the first and second sidewalls at a position interior to the cab which provides visual access to the display by an operator positioned on the operator seat with the cab door in the closed position, the open position overhead of the operator seat, or a transition position between the open and closed positions. 
     In some exemplary embodiments, the cab includes a linkage ( 330 ) coupled to the cab frame and to the cab door and configured to define a path of movement for and support the cab door as the cab door moves between the closed position and the open position overhead of the operator seat. In some embodiments, the linkage is a four-bar linkage. The display is positioned such that neither the cab door nor any links of the linkage obstruct the operator&#39;s view of the display as the cab door moves between the closed position and the open position overhead of the operator seat. In some embodiments, in the open position, the cab door is positioned by the linkage beneath the top of the cab frame. 
     In some embodiments, the cab further includes a joystick controller ( 468 ) positioned forward of the operator seat. The display is mounted to the pillar at a position such that, with the operator seat moved to its forward most position and with the joystick controller raised to its highest position, the display remains a distance ( 484 ) above the joystick controller. In some exemplary embodiments, the distance is at least six inches. 
     In some embodiments, the cab further includes a display mount ( 488 ) mounting the display to the pillar and configured to allow the display to be moved relative to the pillar. The display mount can be configured to allow the display to be rotated between a portrait display position and a landscape display position. 
     In some embodiments, the display is configured to automatically display different information in the portrait display position and the landscape display position. 
     In some embodiments, the cab further includes a camera ( 622 ), and the display is configured to display operational information when in the portrait display position and to display a video feed from the camera when in the landscape display position. In some embodiments, the video feed from the camera is a video feed of a cutting edge of a tool attached to the power machine. 
     In some exemplary embodiments, a cab ( 250 ;  350 ;  450 ;  550 ;  650 ) for a power machine ( 100 ;  200 ) includes a cab frame ( 210 ;  310 ) forming an operator compartment and having a first side wall ( 312 ), a second sidewall ( 314 ), a front ( 316 ), a rear ( 318 ), a top ( 320 ) and a bottom ( 323 ). An operator seat ( 364 ;  464 ;  564 ) is positioned within the cab. A cab door ( 324 ;  424 ;  524 ;  624 ) is configured to cover an opening ( 326 ) in the front of the cab frame when in a closed position and to be moved between the closed position and an open position overhead of the operator seat. A display ( 502 ) is mounted to the cab door at a position which provides visual access to the display by an operator positioned on the operator seat with the cab door in the closed position and with the cab door in the open position overhead of the operator seat. 
     In some embodiments, the display is mounted to the cab door at a position in a bottom half of the cab door and centered in front of the operator seat. Further, in some embodiments, the display is mounted at an angle relative to the cab door such that, with the cab door in the closed position the display is angled upward and with the cab door in the open position overhead of the operator seat the display is angled downward to provide improved viewing angles for the operator with the cab door in both of the closed position and the open position overhead of the operator. In some exemplary embodiments, the angle is between 30 degrees and 60 degrees. 
     In some embodiments, the cab further includes a moveable mount ( 512 ) mounting the display to the cab door and configured to allow an orientation of the display relative to the cab door to be adjusted. 
     In some exemplary embodiments, a cab ( 250 ;  350 ;  450 ;  550 ;  650 ) for a power machine ( 100 ;  200 ) includes a cab frame ( 210 ;  310 ) forming an operator compartment and having a first side wall ( 312 ), a second sidewall ( 314 ), a front ( 316 ), a rear ( 318 ), a top ( 320 ) and a bottom ( 323 ). An operator seat ( 364 ;  464 ;  564 ) is positioned within the cab. A cab door ( 324 ;  424 ;  524 ;  624 ) is configured to cover an opening ( 326 ) in the front of the cab frame when in a closed position and to be moved between the closed position and an open position overhead of the operator seat. A display ( 602 ) is mounted to a portion of the cab frame below the opening ( 326 ) and the cab door when the cab door is in the closed position. 
     In some exemplary embodiments, the display is mounted under a lip ( 626 ) of the cab frame to protect the display and to prevent the display from interfering with operator ingress and egress. 
     In some exemplary embodiments, the cab further includes a camera ( 622 ) and the display, mounted for example below the opening ( 326 ), is configured to display a video feed from the camera. In some exemplary embodiments, the video feed from the camera is a video feed of a cutting edge of a tool attached to the power machine. 
     These and other features of the disclosed cabs and power machines are described in detail below. The above described and other features of the various disclosed embodiments can be included in differing combinations. 
    
    
     
       DRAWINGS 
         FIG. 1  is a block diagram illustrating functional systems of a representative power machine on which embodiments of the present disclosure can be advantageously practiced. 
         FIGS. 2-3  illustrate perspective views of a representative power machine in the form of a skid-steer loader of the type on which the disclosed embodiments can be practiced. 
         FIG. 4  is a side view illustration of a cab, with a door in a closed position and moveable between the closed position and an open position by rotating upward and downward within the cab, having a display positioned on the frame to a side of the door according to one illustrative embodiment. 
         FIG. 4A  is a perspective view illustration of the cab shown in  FIG. 4  with the door in the closed position and with the display omitted to better show features of the cab and door. 
         FIG. 5  is a side view illustration of the cab shown in  FIG. 4  with the door in a partially opened position. 
         FIG. 5A  is a perspective view illustration of the cab shown in  FIG. 5  with the door in the partially opened position and with the display omitted to better show features of the cab and door. 
         FIG. 6  is a side view illustration of the cab shown in  FIG. 4  with the door in a fully opened position. 
         FIG. 7  is a rear-view illustration of a cab similar to the cab shown in  FIG. 4  with a door in a closed position, further illustrating a position of the display in an exemplary embodiment. 
         FIGS. 8 and 9  are, respectively, a side perspective view and a side view the cab shown in  FIG. 7 , further illustrating a position of the display in an exemplary embodiment with the door in a closed position. 
         FIG. 10  is a side view of portions of the cab shown in  FIG. 7  illustrating the display with the door in a partially open position. 
         FIG. 11  is a front view illustration of a portion of a cab, with a door in a closed position and moveable between the closed position and an open position by rotating upward and downward within the cab, having a display positioned on the door according to another illustrative embodiment. 
         FIG. 12  is a rear-view illustration of the cab and display shown in  FIG. 11  with the door in the closed position and the display mounted to the door. 
         FIG. 13  is a front-view illustration of the cab and display shown in  FIG. 11  with the door in the open position and the display mounted to the door. 
         FIGS. 14A and 14B  are diagrammatic illustrations of orientations of a door mounted display with the door in closed and opened positions, respectively. 
         FIG. 15  is a rear perspective view illustration of a portion of a cab having a display positioned beneath a door opening according to another illustrative embodiment. 
         FIG. 16  is a top view illustration of a portion of a cab having a cutting-edge viewing camera according to another illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The concepts disclosed in this discussion are described and illustrated by referring to illustrative 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. 
     Disclosed are displays for cabs, and power machines with cabs, having doors that are moveable between opened and closed positions. In some illustrative embodiments, the door is positioned within an operator compartment of the cab above the operator seat and below a top of the cab when in the opened position. In some embodiments, a display is positioned on a frame adjacent to a door opening at a height which is above a path of an operator joystick, but which does not intersect a path of the door when the door is moved to the opened position above the operator seat and below a top of the cab. In other embodiments, the display is positioned on the door and moves with the door between the closed and opened positions. In these embodiments, the display can be oriented at an angle which allows viewing by an operator with the door in both of the closed and opened positions. In still other embodiments, the display is positioned beneath the door opening. In some embodiments, the display is configured to show the user a cutting-edge view from a camera to aid in the operator&#39;s control of the power machine while using a bucket or other implement to perform a work task. These and other features of the disclosed cabs and power machines are described in detail below. 
     These concepts can be practiced on various power machines, as will be described below. A representative power machine on which the embodiments can be practiced is illustrated in diagram form in  FIG. 1  and one example of such a power machine is illustrated in  FIGS. 2-3  and described below before any embodiments are disclosed. For the sake of brevity, only one power machine is illustrated and discussed as being a representative power machine. However, as mentioned above, the embodiments below can be practiced on any of several power machines, including power machines of different types from the representative power machine shown in  FIGS. 2-3 . 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. Self-propelled work vehicles are a class of power machines that include a frame, work element, and a power source that can provide power to the work element. At least one of the work elements is a motive system for moving the power machine under power. 
       FIG. 1  is a block diagram that illustrates the basic systems of a power machine  100 , which can be any of a number of different types of power machines, upon which the embodiments discussed below can be advantageously incorporated. The block diagram of  FIG. 1  identifies various systems on power machine  100  and the relationship between various components and systems. As mentioned above, at the most basic level, power machines for the purposes of this discussion include a frame, a power source, and a work element. The power machine  100  has a frame  110 , a power source  120 , and a work element  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 and an operator station  150  that provides an operating position for controlling the work elements of the power machine. A control system  160  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. 
     Certain work vehicles have work elements that can perform a dedicated task. For example, some work vehicles have a lift arm to which an implement such as a bucket is attached such as by a pinning arrangement. The work element, i.e., the lift arm can be manipulated to position the implement for performing the task. The implement, in some instances can be positioned relative to the work element, such as by rotating 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. Other work vehicles, however, are intended to be used with a wide variety of implements and have an implement interface such as implement interface  170  shown in  FIG. 1 . At its most basic, implement interface  170  is a connection mechanism between the frame  110  or a work element  130  and an implement, which can be as simple as a connection point for attaching an implement directly to the frame  110  or a work element  130  or more complex, as discussed below. 
     On some power machines, implement interface  170  can include an implement carrier, which is a physical structure movably attached to a work element. 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 as used herein is not merely a pivotal connection point, but rather a dedicated device specifically intended to accept and be secured to various implements. The implement carrier itself is mountable to a work element  130  such as a lift arm or the frame  110 . Implement interface  170  can also include one or more power sources for providing power to one or more work elements on an implement. Some power machines can have a plurality of work element 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 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 is configured to provide power to one or more work elements  130  including the one or more tractive elements  140 , as well as, in some instances, providing power for use by an attached implement via implement interface  170 . Power from the power source  120  can be provided directly to any of the work elements  130 , tractive elements  140 , and implement interfaces  170 . 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 capable of using it to perform a work function. Power sources for power machines typically include an engine such as an internal combustion engine and a power conversion system such as a mechanical transmission or a hydraulic system that is configured to 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. 
       FIG. 1  shows a single work element designated as work element  130 , but various power machines can have any number of work elements. Work elements are typically attached to the frame of the power machine and movable with respect to the frame when performing a work task. In addition, tractive elements  140  are a special case of work element in that their work function is generally to move the power machine  100  over a support surface. Tractive elements  140  are shown separate from the work element  130  because many power machines have additional work elements besides tractive elements, although that is not always the case. Power machines can have any number of tractive elements, some or all of which can receive power from the power source  120  to propel the power machine  100 . Tractive elements can be, for example, track assemblies, wheels attached to an axle, and the like. Tractive elements can be mounted to the frame such that movement of the tractive element is limited to rotation about an axle (so that steering is accomplished by a skidding action) or, alternatively, pivotally mounted to the frame to accomplish steering by pivoting the tractive element with respect to the frame. Power machine  100  includes an operator station  150  that includes an operating position from which an operator can control operation of the power machine. In some power machines, the operator station  150  is defined by an enclosed or partially enclosed cab. 
       FIGS. 2-3  illustrate a loader  200 , which is one particular example of a power machine of the type illustrated in  FIG. 1  where the embodiments discussed below can be advantageously employed. Loader  200  is a skid-steer loader, which is a loader that has tractive elements (in this case, four wheels) that are mounted to the frame of the loader via rigid axles. Here the phrase “rigid axles” refers to the fact that the skid-steer loader  200  does not have any tractive elements that can be rotated or steered to help the loader accomplish a turn. Instead, a skid-steer loader has a drive system that independently powers one or more tractive elements on each side of the loader so that by providing differing tractive signals to each side, the machine will tend to skid over a support surface. These varying signals can even include powering tractive element(s) on one side of the loader to move the loader in a forward direction and powering tractive element(s) on another side of the loader to mode the loader in a reverse direction so that the loader will turn about a radius centered within the footprint of the loader itself. The term “skid-steer” has traditionally referred to loaders that have skid steering as described above with wheels as tractive elements. However, it should be noted that many track loaders also accomplish turns via skidding and are technically skid-steer loaders, even though they do not have wheels. For the purposes of this discussion, unless noted otherwise, the term skid-steer should not be seen as limiting the scope of the discussion to those loaders with wheels as tractive elements. 
     Loader  200  is one particular example of the power machine  100  illustrated broadly in  FIG. 1  and discussed above. To that end, features of loader  200  described below include reference numbers that are generally similar to those used in  FIG. 1 . For example, loader  200  is described as having a frame  210 , just as power machine  100  has a frame  110 . The loader  200  should not be considered limiting especially as to the description of features that loader  200  may have described herein that are not essential to the disclosed embodiments and thus may or may not be included in power machines other than loader  200  upon which the embodiments disclosed below may be advantageously practiced. Unless specifically noted otherwise, embodiments disclosed below can be practiced on a variety of power machines, with the loader  200  being only one of those power machines. For example, some or all of the concepts discussed below can be practiced on many other types of work vehicles such as various other loaders, excavators, trenchers, and dozers, to name but a few examples. 
     Loader  200  includes frame  210  that supports a power system  220 , the power system can generate or otherwise providing power for operating various functions on the power machine. Power system  220  is shown in block diagram form, but is located within the frame  210 . Frame  210  also supports a work element in the form of a lift arm assembly  230  that is powered by the power system  220  and can perform various work tasks. As loader  200  is a work vehicle, frame  210  also supports a traction system  240 , which is also powered by power system  220  and can propel the power machine over a support surface. The lift arm assembly  230  in turn supports an implement interface  270 , which includes an implement carrier  272  that can receive and securing various implements to the loader  200  for performing various work tasks and power couplers  274 , to which an implement can be coupled for selectively providing power to an implement that might be connected to the loader. Power couplers  274  can provide sources of hydraulic or electric power or both. The loader  200  includes a cab  250  that defines an operator station  255  from which an operator can manipulate various control devices  260  to cause the power machine to perform various work functions. Cab  250  is accessible from an opening in the front of the cab. Although not shown in  FIGS. 2-3 , in many instances, a door is provided to cover the opening and is positionable between a closed and an opened position. Many of these doors are pivotally mounted about a vertical axis so that door pivots outward from the door when in the opened position. When the door is in the opened position, it is necessary for the lift arm  234  (as discussed below) to be in in the lowered position because the door would otherwise interfere with the lift arm or components on the lift arm, specifically tilt cylinder actuators. Cab  250  can be pivoted back about an axis that extends through mounts  254  to provide access to power system components as needed for maintenance and repair. Access to power system components can also be provided by opening a tailgate  280  that is pivotally mounted to the frame  210  of the power machine at a rear end thereof. 
     The operator station  255  includes an operator seat  258  and a plurality of operation input devices, including control levers  260  that an operator can manipulate to control various machine functions. Operator input devices can include buttons, switches, levers, sliders, pedals, and the like that can be stand-alone devices such as hand operated levers or foot pedals or incorporated into hand grips or display panels, including programmable input devices. Actuation of operator input devices can generate signals in the form of electrical signals, hydraulic signals, and/or mechanical signals. Signals generated in response to operator input devices are provided to various components on the power machine for controlling various functions on the power machine. Among the functions that are controlled via operator input devices on power machine  100  include control of the tractive elements  219 , the lift arm assembly  230 , the implement carrier  272 , and providing signals to any implement that may be operably coupled to the implement. 
     Loaders can include human-machine interfaces including display devices that are provided in the cab  250  to give indications of information relatable to the operation of the power machines in a form that can be sensed by an operator, such as, for example audible and/or visual indications. Audible indications can be made in the form of buzzers, bells, and the like or via verbal communication. Visual indications can be made in the form of graphs, lights, icons, gauges, alphanumeric characters, and the like. Displays can be dedicated to providing dedicated indications, such as warning lights or gauges, or dynamic to provide programmable information, including programmable display devices such as monitors of various sizes and capabilities. Display devices can provide diagnostic information, troubleshooting information, instructional information, and various other types of information that assists an operator with operation of the power machine or an implement coupled to the power machine. Other information that may be useful for an operator can also be provided. Other power machines, such walk behind loaders may not have a cab nor an operator compartment, nor a seat. The operator position on such loaders is generally defined relative to a position where an operator is best suited to manipulate operator input devices. 
     Various power machines that can include and/or interacting with the embodiments discussed below can have various frame components that support various work elements. The elements of frame  210  discussed herein are provided for illustrative purposes and frame  210  is not the only type of frame that a power machine on which the embodiments can be practiced can employ. Frame  210  of loader  200  includes an undercarriage or lower portion  211  of the frame and a mainframe or upper portion  212  of the frame that is supported by the undercarriage. The mainframe  212  of loader  200 , in some embodiments is attached to the undercarriage  211  such as with fasteners or by welding the undercarriage to the mainframe. Alternatively, the mainframe and undercarriage can be integrally formed. Mainframe  212  includes a pair of upright portions  214 A and  214 B located on either side and toward the rear of the mainframe that support lift arm assembly  230  and to which the lift arm assembly  230  is pivotally attached. The lift arm assembly  230  is illustratively pinned to each of the upright portions  214 A and  214 B. The combination of mounting features on the upright portions  214 A and  214 B and the lift arm assembly  230  and mounting hardware (including pins used to pin the lift arm assembly to the mainframe  212 ) are collectively referred to as joints  216 A and  216 B (one is located on each of the upright portions  214 ) for the purposes of this discussion. Joints  216 A and  216 B are aligned along an axis  218  so that the lift arm assembly is capable of pivoting, as discussed below, with respect to the frame  210  about axis  218 . Other power machines may not include upright portions on either side of the frame, or may not have a lift arm assembly that is mountable to upright portions on either side and toward the rear of the frame. For example, some power machines may have a single arm, mounted to a single side of the power machine or to a front or rear end of the power machine. Other machines can have a plurality of work elements, including a plurality of lift arms, each of which is mounted to the machine in its own configuration. Frame  210  also supports a pair of tractive elements in the form of wheels  219 A-D on either side of the loader  200 . 
     The lift arm assembly  230  shown in  FIGS. 2-3  is one example of many different types of lift arm assemblies that can be attached to a power machine such as loader  200  or other power machines on which embodiments of the present discussion can be practiced. The lift arm assembly  230  is what is known as a vertical lift arm, meaning that the lift arm assembly  230  is moveable (i.e. the lift arm assembly can be raised and lowered) under control of the loader  200  with respect to the frame  210  along a lift path  237  that forms a generally vertical path. Other lift arm assemblies can have different geometries and can be coupled to the frame of a loader in various ways to provide lift paths that differ from the radial path of lift arm assembly  230 . For example, some lift paths on other loaders provide a radial lift path. Other lift arm assemblies can have an extendable or telescoping portion. Other power machines can have a plurality of lift arm assemblies attached to their frames, with each lift arm assembly being independent of the other(s). Unless specifically stated otherwise, none of the inventive concepts set forth in this discussion are limited by the type or number of lift arm assemblies that are coupled to a particular power machine. 
     As referred to briefly above, the lift arm assembly  230  has a pair of lift arms  234  that are disposed on opposing sides of the frame  210 . A first end of each of the lift arms  234  is pivotally coupled to the power machine at joints  216  and a second end  232 B of each of the lift arms is positioned forward of the frame  210  when in a lowered position as shown in  FIG. 2 . Joints  216  are located toward a rear of the loader  200  so that the lift arms extend along the sides of the frame  210 . The lift path  237  is defined by the path of travel of the second end  232 B of the lift arms  234  as the lift arm assembly  230  is moved between a minimum and maximum height. 
     Each of the lift arms  234  has a first portion  234 A of each lift arm  234  is pivotally coupled to the frame  210  at one of the joints  216  and the second portion  234 B extends from its connection to the first portion  234 A to the second end  232 B of the lift arm assembly  230 . The first portions  234 A of the lift arms  234  are each coupled to each other via a cross member  236 . Cross member  236  provides increased structural stability to the lift arm assembly  230 . The second portions  234 B via a cross member  239  that is attached to each of the second portions of the lift arms  234 B. Cross member  239  provides increased structural stability to the lift arm assembly  230 . 
     A pair of actuators  238 , which on loader  200  are hydraulic cylinders configured to receive pressurized fluid from power system  220 , are pivotally coupled to both the frame  210  and the lift arms  234  at pivotable joints  238 A and  238 B, respectively, on either side of the loader  200 . The actuators  238  are sometimes referred to individually and collectively as lift cylinders. Actuation (i.e., extension and retraction) of the actuators  238  cause the lift arm assembly  230  to pivot about joints  216  and thereby be raised and lowered along a fixed path illustrated by arrow  237 . Each of a pair of control links  217  are pivotally mounted to the frame  210  and one of the lift arms  232  on either side of the frame  210 . The control links  217  help to define the fixed lift path of the lift arm assembly  230 . 
     Some lift arms, most notably lift arms on excavators but also possible on loaders, may have portions that are controllable to pivot with respect to another segment instead of moving in concert (i.e. along a pre-determined path) as is the case in the lift arm assembly  230  shown in  FIG. 2 . Some power machines have lift arm assemblies with a single lift arm, such as is known in excavators or even some loaders and other power machines. Other power machines can have a plurality of lift arm assemblies, each being independent of the other(s). 
     An implement interface  270  is provided proximal to a second end  232 B of the lift arm assembly  234 . The implement interface  270  includes an implement carrier  272  that can accept and securing a variety of different implements to the lift arm  230 . Such implements have a complementary machine interface that is configured to be engaged with the implement carrier  272 . The implement carrier  272  is pivotally mounted at the second end  232 B of the arm  234 . Implement carrier actuators  235  are operably coupled the lift arm assembly  230  and the implement carrier  272  and are operable to rotate the implement carrier with respect to the lift arm assembly. Implement carrier actuators  235  are illustratively hydraulic cylinders and often known as tilt cylinders. 
     By having an implement carrier capable of being attached to a plurality of different implements, changing from one implement to another can be accomplished with relative ease. For example, machines with implement carriers can provide an actuator between the implement carrier and the lift arm assembly, so that removing or attaching an implement does not involve removing or attaching an actuator from the implement or removing or attaching the implement from the lift arm assembly. The implement carrier  272  provides a mounting structure for easily attaching an implement to the lift arm (or other portion of a power machine) that a lift arm assembly without an implement carrier does not have. 
     Some power machines can have implements or implement like devices attached to it such as by being pinned to a lift arm with a tilt actuator also coupled directly to the implement or implement type structure. A common example of such an implement that is rotatably pinned to a lift arm is a bucket, with one or more tilt cylinders being attached to a bracket that is fixed directly onto the bucket such as by welding or with fasteners. Such a power machine does not have an implement carrier, but rather has a direct connection between a lift arm and an implement. 
     The implement interface  270  also includes an implement power source  274  available for connection to an implement on the lift arm assembly  230 . The implement power source  274  includes pressurized hydraulic fluid port to which an implement can be removably coupled. The pressurized hydraulic fluid port selectively provides pressurized hydraulic fluid for powering one or more functions or actuators on an implement. The implement power source can also include an electrical power source for powering electrical actuators and/or an electronic controller on an implement. The implement power source  274  also exemplarily includes electrical conduits that are in communication with a data bus on the excavator  200  to allow communication between a controller on an implement and electronic devices on the loader  200 . 
     The description of power machine  100  and loader  200  above is provided for illustrative purposes, to provide illustrative environments on which the embodiments discussed below can be practiced. While the embodiments discussed can be practiced on a power machine such as is generally described by the power machine  100  shown in the block diagram of  FIG. 1  and more particularly on a loader such as loader  200 , unless otherwise noted or recited, the concepts discussed below are not intended to be limited in their application to the environments specifically described above. 
       FIG. 4  is a side view illustration of a cab  350  providing an operator compartment or station  355  with a display  302  configured and positioned to facilitate the use of an overhead opening door, according to one illustrative embodiment.  FIG. 4A  is a perspective view of cab  350 , with the display  302  omitted to simplify the illustration of other cab and door features.  FIGS. 4 and 4A  illustrate cab  350  with the door in the closed position.  FIGS. 5 and 5A  are side and perspective view illustrations of cab  350  with the door in a partially open position. Display  302  is omitted in  FIG. 5A  to simplify the illustration of other cab and door features.  FIG. 6  is a side view illustration of the cab  350  with the door in the fully opened position. 
     Cab  350  is generally similar to the cab  250  in the sense that it provides an operator station such as operator station  150  discussed above. Cab  350  also advantageously provides an improved structure that allows a door to be moved between closed and opened positions to provide an operator better cab ingress and egress, prevents door interference with a lift arm structure, and minimizes interference with operator visibility. Display  302  is mounted within cab  350  in a corner at a position that both provides the operator with improved visual access to the display and avoids interference with a door  324  and door linkages ( 330 , see below) as the door is moved from a closed position to an opened position above the operator&#39;s head. Other benefits of various disclosed embodiments will also be apparent in the following disclosure. 
     Cab  350  has a cab frame  310  having first and second side walls  312  and  314 , a front side  316 , a rear side  318 , a top side  320 , and a bottom side  323 . Display  302  is mounted in a corner between the front side  316  and side wall  312  on an interior of the cab as is described below in greater detail. As shown, the display  302  is mounted on a right-hand side of the cab from the perspective of an operator. Although not shown here, the display  302  is, in some embodiments, mounted on the left-hand side of the operator. 
     A seat  364  is supported on the bottom side  323  of the cab frame  310 . The cab frame  310  also defines a lower portion  322 , positioned below the bottom side  323 , where the seat is supported in which an operator can position feet during machine operation. As shown, the front side  316  of the cab  350  extends down and forms a front of the lower portion  322 . The remainder of the bottom portion can be formed from individual pieces of material and attached such as by welding to the side walls  312  and  314  or parts of the lower portion  322  can be formed as part of the side walls. In  FIGS. 4 and 4A , cab door  324  is in a closed position at the front of the operator compartment  350  covering an opening  326  in front portion  316  of frame  310 .  FIGS. 5 and 5A  illustrate cab door  324  in a partially open position, and  FIG. 6  illustrates cab door  324  in a fully open position. Cab door  324  includes, in some embodiments, a cover portion  328  that at least partially covers and/or forms a part of, lower portion  322  when door  324  is in the illustrated closed position. In some exemplary embodiments, cover  328  is raised and lowered with door  324 . Thus, when door  324  is raised to the open position shown in  FIG. 6 , the opening  326  through which the operator moves into and out of the cab is fully or nearly fully unobstructed to provide improved ingress and egress. The cover portion  328  is shown as extending beyond (i.e., forward of) top side  320  in the opened position, but in some embodiments, the cover portion does not extend beyond the top side  320 . 
     In some exemplary embodiments, a linkage  330  is provided on each of first and second sides  312  and  314  to couple door  324  to frame  310  and to control movement of the door between closed and open positions along a configured path. The linkage  330  shown in  FIGS. 4-6  is a four-bar linkage arrangement that includes a first link  332  and a second link  342  each of which are pivotally attached to the frame  310  and the door  324 . The first link  332  is pivotally attached to frame  310  at first pivot connection  334 . Portions of the frame  310  between attachment points of links  332  and  342  to the frame act as the third link of the four-bar linkage. The portion of the door  324  between the connection points provides the fourth link of the four-bar linkage  330 . In exemplary embodiments, four-bar linkage  330  includes features that provide a movement path for door  324  such that, when moved to a fully open position (shown in  FIG. 6 ), door  324  is positioned horizontally above the operator&#39;s head, but inside or substantially inside of the cab. Thus, in the fully opened position, door  324  extends at least partially horizontally beneath the top side  320  as is discussed below in greater detail. While raising door  324  along the movement path provided by four-bar linkage  330 , door  324  extends beyond a front plane (represented by dashed line  370 ) of cab  350  as shown  FIG. 5 , but does not interfere with any portion of the lift arm (such as, for example, cross member  239  shown in  FIG. 2 ) of the power machine, regardless of the position of the lift arm relative to the frame (i.e., whether it is fully lowered or not). Alternatively, the door can be positioned so that it does not extend forward of the front side  316  of the cab  350 . Further, display  302  mounted on pillar  382  to one side (e.g., the right side) of the operator seat is positioned such that neither door  324  nor any of the individual links of linkage  330  contact the display as the door moves from the closed position to the opened position as shown in  FIG. 5 . The links and door also do not obstruct the operator&#39;s view of display  302  as the door moves from the closed position to the overhead opened position. 
     In the illustrated embodiment, first link  332  of the four-bar linkage has a first pivot connection  334  to the frame  310  configured to allow link  332  to rotate relative to frame  310 . Link  332  also has a second pivot connection  336 , to door  324 , which is better shown in the partially open-door position of  FIGS. 5 and 5A . Second pivot connection  336  is configured to allow link  332  and door  324  to pivot relative to one another. In some exemplary embodiments, first link  332  includes at least a first link section  338  and a second link section  340 , which are best shown in  FIG. 5 . Link sections  338  and  340  of first link  332  are rigidly connected or continuously formed such that sections  338  and  340  do not pivot or rotate relative to each other. In some embodiments, link sections  338  and  340  are oriented or arranged such that the link sections form an obtuse angle relative to one another. Forming an obtuse angle between link sections  338  and  340  of first link  332  can, in various embodiments, serve several purposes. For example, such a configuration provides the range of motion over which door  324  movement is constrained between the closed and open positions. Further, while providing that door movement, the obtuse angle between link sections  338  and  340  allows link section  340  to be positioned along a horizontally extending reinforcement  360  of the cab side wall  312  when door  324  is in the closed position. This prevents or reduces obstruction of the operator&#39;s view by first link  332 , and thereby improves visibility. 
     Similar to first link  332 , second link  342  of the four-bar linkage has a first pivot connection  344  to the frame  310  configured to allow link  342  to rotate relative to frame  310 . For example, pivot connection  344  can be on or near horizontally extending reinforcement  360 , or elsewhere on side wall  312 . As shown in the simplified illustration of  FIGS. 4-6 , portions of horizontally extending reinforcement  360  or of side wall  312  are removed to better show a location of pivot connection  344 . Second link  342  also has a second pivot connection  346 , to door  324 , which is again better shown in  FIG. 6 . Second pivot connection  346  is configured to allow link  342  and door  324  to pivot relative to one another. 
     Like first link  332 , in some exemplary embodiments, second link  342  includes at least a first link section  348  and a second link section  352 , which are best shown in  FIG. 5 . Link sections  348  and  352  of second link  342  are rigidly connected or continuously formed such that sections  348  and  352  do not pivot or rotate relative to each other. Also like first link  332 , in some embodiments of second link  342 , link sections  348  and  352  are oriented or arranged such that the link sections form an obtuse angle relative to one another to move door  324  along the desired path, and in order to allow link section  352  to be positioned along horizontally extending reinforcement  360  when door  324  is in the closed position. The obtuse angle formed by sections of link  342  need not be the same as the obtuse angle formed by sections of link  332 . This masking of the links  332  and  342  by the cab structure when the door is in the closed position can provide significant improvement in side visibility by an operator of the power machine. Also, providing the links  332  and  342  as shown for each four-bar linkage allows coupling of the door  324  to the cab without hindering or interfering with forward visibility of the operator when the door is in the fully opened position shown in  FIG. 6 . In other embodiments, different linkages can be employed. Such linkages can be positioned in alternative positions from the linkage  330  to remain as unobtrusive to the operator as possible. One advantageous feature of the linkage configuration shown in FIGs. is that as the door moves from a closed position to an open position, a bottom portion of the door extends out of the operator compartment space. As a result, the door moves along a path that allows for maximum headroom while the door is moving. In addition, the portion of the door that extends out of the cab also clears the lift arm no matter where the lift arm is positioned along its travel path. Various linkages can be used to position the door and insofar as the position of the display in the cab is concerned, no one linkage arrangement is vital if the linkage does not interfere with the display when moving from one position to another or especially if the linkage does not impair the view of the display from an operator&#39;s perspective. The linkages themselves and how they operate to move the door between a closed position and an opened position above the operator&#39;s head are a separate matter from the position of the display and various embodiments have their own unique advantages. 
     In exemplary embodiments, placement of pivot connections  334  and  344  has been found to allow for improved or optimized operation of the four-bar linkage  330  in moving door  324  along its configured path, while also allowing impact on visibility to be reduced. For example, in some exemplary embodiments, it has been found that placement of lower pivot connection  334 , from a side view perspective, rearward of an operator seatback  362  and below an operator seat  364  provides improved results. Also, in some exemplary embodiments, it has been found that placement of upper pivot connection  344  vertically near the horizontal reinforcing member  360  is beneficial. In some alternative or more specific embodiments, placement of upper pivot connection  344  below a horizontally extending center line  366  (centered vertically) of the cab side wall  312  provides improved results. In some embodiments, upper pivot connection  344  can be in a position forward of seat back  362  but rearward of joystick  368 . For example, upper pivot connection  344  can be positioned at or adjacent to the Seat Index Point (SIP) for the operator seat, as defined by the seat manufacturer according to a standard such as the European Standard EN ISO 3411:2007. 
     Referring now to  FIGS. 7-10 , shown is another embodiment of a cab  450 , similar to cab  350  shown in  FIGS. 4-6 , having a display  402  mounted on a pillar  482  forward and to one side of operator seat  464 . In the illustrated embodiment, the display  402  is mounted on the right-hand side of the operator seat  464 . However, in other embodiments, display  402  can be mounted to the left-hand side of the operator seat. In still other embodiments, display  402  can be moveable between data ports on the pillars on either side of the operator seat. 
     Cab  450  has a door  424  at the front of the cab that opens to an overhead position using a linkage  430  on each side of cab  450 . Linkage  430  can be similar to linkage  330 , though they need not have the same configuration of individual links. Generally, linkages  430  on each side of the operator seat  464  in cab  450  are four-bar linkages, with the moveable individual links moving on the sides of the cab in positions that do not interfere with the operator, the joysticks  468 , or the display  402 . Seat  464  can be configured to slide forward and backward to accommodate different sized operators, and joysticks  468  can be configured to be moved up and down for the same purpose. The display  402  is positioned at a height such that, even with the seat  464  moved all the way forward and joysticks  468  raised to their highest positions, the display remains a distance  484  (shown in  FIG. 7 ) above the corresponding (e.g., right hand side) joystick  468 . The distance  484  is selected such that the display does not interfere with the corresponding joystick  468  or the operator&#39;s hand (positioned on the joystick) at any point along the joystick path, even at the highest joystick position along the arcuate path of the joystick, at the forward most actuated position of the joystick, etc. In one embodiment, distance  484  is at least six inches. 
     In some embodiments, display  402  is also positioned at a height such that the display remains a second distance  486  (shown in  FIG. 10 ) below door  424  as the door moves between its closed position (shown in  FIGS. 7-9 ) toward the overhead opened position.  FIG. 10  illustrates door  424  in an intermediate position along the path toward the overhead opened position. In one exemplary embodiment, the second distance  486  is at least two inches. Display  402  is configured to be useable by the operator with the door at any position. Thus, the display can be used not only with the door fully closed, but also with the door fully opened and stored overhead of the operator. Further, the display remains operational at intermediate positions of the door as the door travels between the closed and open positions such that if the door can be maintained in an intermediate position (and this is not the case with the linkages  430 ) the display is still visible to the operator, unobstructed by any of the door  424  or any linkages that movably attach the door  424  to the frame. 
     In exemplary embodiments, the display  402  can be mounted to pillar  482  using a display mount  488  (shown in  FIG. 9 ). Mount  488  can be any type of display mount that is suitable for attaching the display to the cab  450 . For example, display mount  488  can be a hinged display mount that allows the display  402  to be moved or rotated to change viewing angles for different operators, to move the display during ingress into and egress from the cab, etc. In other embodiments, a spherical ball joint can be used to allow the display to be moved for these or other purposes. In still other embodiments, the display is configured to be rotated between portrait and landscape positions, and to change the user interface represented on the display based upon the portrait or landscape position of the display. For instance, the display can be configured to show the user operational control information while in the portrait orientation, and to show the user a video feed from a camera while in the landscape orientation. This would allow the display to show the user a camera view of the cutting edge of an attached bucket or implement to allow the user better control in a work operation. A cutting-edge viewing system is described in further detail below with reference to  FIGS. 15-16 . In still other embodiments, the display can be fixed to the pillar  482  and not moveable. 
       FIGS. 11-13  illustrate another embodiment of a cab  550 , like cabs  350  and  450 , having a front entry door  524  which moves from a closed position (shown in the front and rear views of  FIGS. 11 and 12 , respectively) to an overhead opened position (shown in  FIG. 13 ). The linkages used to move the door between the open and closed positions are not illustrated but can be the same or like the linkages discussed above with reference to cabs  350  and  450 . Also shown in cab  550  are an operator seat  564 , joysticks  568 , and a display  502 . 
     In cab  550 , display  502  is positioned on door  524 , centered between the knees of the operator when seated on seat  564 . Display  502  is positioned toward a bottom of door  524  and is oriented or angled upward (when the door is in the closed position) to provide an improved viewing angle to a seated operator.  FIG. 14A  provides a diagrammatic illustration of display  502  mounted on door  564  with the door in the closed position (shown in  FIGS. 11 and 12 ). In this position, display  502  is oriented upward with the direction  504  orthogonal to the display screen at an angle Θ relative to the horizontal direction  506 . 
     As the door moves to the overhead open position shown in  FIG. 13 , the orientation of the display relative to the door remains fixed. Thus, in the open-door position, the display is oriented or angled downward to provide an improved viewing angle to the seated operator. FIG.  14 B provides a diagrammatic illustration of display  502  and door  564  with the door in the opened position. In exemplary embodiments, angle Θ is selected to provide optimized viewing of the display in the combination of closed and open-door positions. In one exemplary embodiment, angles Θ of between 30 degrees and 60 degrees have been found to provide an optimized combination of viewing in the closed and open positions. The diagrammatic representations of display  502  and door  564  are not intended to provide a representation of actual door shapes, orientations, etc., but instead are provided to represent the selection of a display orientation relative to a reference direction such as the horizontal direction. 
     In some embodiments, display  502  is mounted on door  524  using a moveable mount  512  which allows the orientation of the display relative to the door or relative to the horizontal direction to be adjusted. The adjustment can be made by the operator, which allows the operator to select the display position for optimized viewing in each of the closed and open-door positions. In other embodiments, the adjustment of display orientation can be automatic using a mechanism or an actuator such as a small electric motor guided with the input from an inclinometer to automatically change the orientation of the display relative to the door or relative to the horizontal direction in different door positions. In still other embodiments, the angle of the display is fixed. 
     Referring now to  FIG. 15 , shown is another embodiment of a cab  650 , similar to cabs  350 ,  450  and  550 , having a front entry door  624  which moves from a closed position to an overhead opened position. In cab  650 , a display  602  is mounted to a portion  622  of the frame below the door  624 . In this position, display  602  is mounted to the frame near the operator&#39;s feet when seated in the cab, and remains in this position regardless of whether the door  624  is closed or opened. In exemplary embodiments, display  602  is mounted under a lip  626  of the frame below the door to protect display  602  and prevent the display from interfering with operator ingress and egress. In some embodiments display  602  is positioned within a protective casing  604  to protect the display  602  from being damaged by contact with the operator&#39;s feet, mud, moisture, etc. 
     In some embodiments, display  602  is configured to provide the operator with a video feed, from a camera  622  (shown in  FIG. 16 ), of the cutting edge  626  of an implement  628  coupled to the front of the power machine. Camera  622  can be mounted on brow  621  of cab top  620 , or in any suitable position, and oriented toward cutting edge  626 . When looking at the cutting edge  626  without such a system, operators conventionally have been required to look generally downward toward the cutting-edge of an implement. Thus, the low position of display  602  in cab  650  with a cutting-edge viewing system provides an improved cutting-edge view, while allowing the operator to look generally in the conventional direction for observing the cutting edge. 
     While camera  622  is illustrated with reference to cab  650  and display position  602 , camera  622  can be used with any cab and any display position to provide a video feed of a view of cutting edge  626  of implement  628 . Further, it is not required that the display providing the cutting-edge view to the operator be dedicated for only this purpose. Instead, the display can be multi-purpose and can change the displayed information either automatically, or in response to an input from the operator. As mentioned above, in some embodiments, the display can be configured to change the displayed information to automatically provide the cutting-edge view when the display is rotated from a portrait orientation to a landscape orientation. 
     The discussion above provides several important advantages. Included is the ability to mount a display in various locations within an operator compartment to accommodate a door that opens to an overhead position. In the various embodiments, the display is positioned in locations that allow freedom of movement of such a door while also providing convenient locations for an operator to view the display, irrespective of the position of the door. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the discussion.