Patent Application
20210039729
The present disclosure relates generally to adjusting idler height in an undercarriage system of a track-type machine, and more particularly to an idler height adjustment system where a conduit fluidly connects piston assemblies adjustable to set idler height by exchanging a flowable material.
Track-type machines are used in many applications throughout the world such as construction, forestry, landfills, mining, demolition, and in various other environments. In a typical design, an endless loop of coupled together track links is positioned at each side of the machine and extends about a plurality of rotatable track engaging elements. Track-type machines, and the undercarriage system including the tracks in particular, can be subjected to extremely harsh conditions. Side loading, bending loads upon components, twisting loads, impacts, and a variety of other phenomena can lead to track strain, wear, and performance degradation. The materials at a work site, including hard rock materials, sand, clay, landfill trash, and various other materials can intrude between and among components in the track. Motion of components in the undercarriage system in contact with one another tends to wear away material from which the undercarriage components are made, which wear can be accelerated or exacerbated by the worksite materials. As a result, machine tracks and related components are often built with a particular service life in mind, taking advantage of expected wear patterns and wear rates in the basic design of a component.
It is nevertheless typically necessary to service undercarriage systems over the course of a field service life, to tighten or otherwise adjust the track, inspect and replace seals, and perform other basic maintenance. One phenomenon that can require machine downtime relates to addressing idler height changes in response to wearing of undercarriage system components. The idler is a rotatable track engaging element that passively rotates and guides the track as it is driven by way of a drive sprocket. As material is worn away from the idler, from the track, and potentially other components, the position of the idler relative to other components can change. Idler height that is too great can cause track that is advanced around the idler to contact the underlying substrate at a location that is aft of a desired location, whereas when idler height is too low the track can contact the substrate at a location that is further forward than desired. In either case, the ride quality and performance of the machine can be adversely affected.
Various techniques have been proposed over the years to enable the idler height to be adjusted. Shim packs and the like are sometimes provided and carried on board the machine, with individual shims being movable from a position above the idler to a position below the idler as wear of the undercarriage components causes idler height to drift lower over time. Still other techniques involve idler support blocks that have off-center holes for the idler shaft. As idler height changes the support blocks can be repositioned to support the idler shaft at different heights. These and other idler height adjustment strategies can be labor intensive and require breaking the track, necessitating machine downtime. One known idler height adjustment strategy is set forth in U.S. Pat. No. 7,237,631 to Livesay et al.
In one aspect, an idler height adjustment system for an idler in an undercarriage system of a track-type machine includes a first piston assembly having a first piston movable between an advanced position and a retracted position, a second piston assembly including a second piston movable between an advanced position and a retracted position, and a frame supporting the first piston assembly and the second piston assembly in opposition to one another for positioning, respectively, above and below an idler support element in the undercarriage. The system further includes a conduit connecting the first piston assembly to the second piston assembly, and a fluid exchange valve within the conduit and adjustable from a closed position, to an open position to exchange a flowable material through the conduit between the first piston assembly and the second piston assembly.
In another aspect, an undercarriage system for a track-type machine includes an idler yoke, and an idler support element coupled to the idler yoke. The system further includes a first piston assembly and a second piston assembly supported, respectively, at an upper location and a lower location relative to the idler support element and in opposition to one another. The system also includes a conduit connecting the first piston assembly to the second piston assembly, and a fluid exchange valve within the conduit and adjustable from a closed position, to an open position to fluidly connect the first piston assembly and the second piston assembly.
In still another aspect, a method of adjusting a height of an idler in an undercarriage system of a track-type machine includes opening a fluid exchange valve in a conduit extended between a first piston assembly supported at an upper side of an idler support element in the undercarriage system, and a second piston assembly supported at a lower side of the idler support element. The method further includes repositioning the idler support element relative to a track roller frame in the undercarriage system while the fluid exchange valve is open, and covarying positions of pistons in the first piston assembly and the second piston assembly based on the repositioning of the idler support element. The method still further includes displacing a flowable material through the conduit based on the covarying of the positions of the pistons, and closing the fluid exchange valve to set a height of the idler after the displacement of the flowable material.
Referring to
Referring also now to
In the illustrated embodiment, frame 42 includes a support frame having an upper arm 56 in contact with first piston assembly 44, a lower arm 58 in contact with second piston assembly 38, and a U-bend 60 connecting upper arm 56 and lower arm 58. U-bend 60 can have a generally U-shaped configuration, and a variety of shapes not strictly adherent to a “U” could be functionally and structurally analogous to the configuration depicted in the drawings. Frame 42 has a plurality of bolt holes 62 formed therein, each receiving a bolt, for bolting frame 42 to a track roller frame 22 in undercarriage system 18. It can further be noted that upper arm 56 forms a first receptacle 64 and lower arm 58 forms a second receptacle 66, with first receptacle 64 and second receptacle 66 receiving, respectively, first piston assembly 34 and second piston assembly 38. An idler shaft 54 extends into idler support element 44, with idler yoke 50 generally supporting idler 30 for rotation. Idler yoke 50 could be coupled with an idler recoil system (not shown) such as one or more mechanical springs or gas springs in some embodiments. It will be appreciated that system 32 includes substantially identical, but potentially mirror image, components upon each side of idler 30. In particular, first piston assembly 34 and second piston assembly 38 may be positioned at a first side of track roller frame 22, and a third piston assembly, a fourth piston assembly, and a second conduit connecting the third piston assembly to the fourth piston assembly, may be positioned at a second side of track roller frame 22. Description and discussion herein of components at one side of track roller frame 22, and depicted in side views in
It will be recalled that a conduit 46 connects first piston assembly 34 to second piston assembly 38. A fluid exchange valve 48 is positioned within conduit 46 and adjustable from a closed position, to an open position to exchange a flowable material through conduit 46 between first piston assembly 34 and second piston assembly 38. A second conduit and second fluid exchange valve configured in a like manner may be positioned at the second side of track roller frame 32. In the illustrated embodiment, conduit 46 extends through each of upper arm 56 and lower arm 58 to feed flowable material to and from first piston assembly 34 and second piston assembly 38. In
As noted above, conduit 46 carries a flowable material between first piston assembly 34 and second piston assembly 38. Fluid exchange valve 48 may have a closed position to block fluid connection between first piston assembly 34 and second piston assembly 38, and moved to an open position to fluidly connect first piston assembly 34 and second piston assembly 38, the significance of which will be further apparent from the following description. It should further be understood that exchanging flowable material through conduit 46 between first piston assembly 34 and second piston assembly 38 should not be taken to mean that fluid within one of the piston assemblies necessarily flows all the way to the other one of the piston assemblies when exchange of flowable material occurs. In other words, opening fluid exchange valve 46 can be understood to fluidly connect two sides of system 32, such that flowable material from one side passes to the other side, even if that material is not literally exchanged between the piston assemblies.
In a practical implementation strategy, the flowable material includes a grease filling conduit 46. A grease as contemplated herein will typically be a semisolid or semifluid composition such as that obtained by mixing oil and a thickener such as soap. Oil alone could be used, however, a grease such as a mineral oil grease or a vegetable oil grease provides a practical implementation strategy. System 32 can include a grease port 86 at a location that is fluidly between first piston 36 and second piston 40. A closure 88 blocks grease port 86.
Referring also to
Referring to the drawings generally, but also now to
With continued reference to
As explained above, performance such as grading performance and ride quality of a track-type tractor or certain other machines can depend substantially on an idler height to roller height relationship. This relationship changes over time due to wearing of the components. It will thus be appreciated that the present disclosure provides a much more easily adjusted system and a repeatable method than certain other strategies. In the illustrated embodiments, an operator or technician can manipulate an external handle 72 of fluid exchange valve 48 to allow grease to flow in conduit 46. In other instances, rather than a manually operated system, height monitoring or ride quality monitoring, or monitoring and analysis of other parameters, could be used in an electronically controlled system that would selectively electro-mechanically open and close a fluid exchange valve generally analogous to the manual operation discussed herein.
The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
