U.S. patent application number 13/443429 was filed with the patent office on 2012-08-02 for machine and track assembly for use therewith.
This patent application is currently assigned to CATERPILLAR, INC.. Invention is credited to Donovan S. Clarke, Mark S. Diekevers, Victor M. Penrod, Roger L. Recker, Kevin L. Steiner.
Application Number | 20120193978 13/443429 |
Document ID | / |
Family ID | 40221344 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120193978 |
Kind Code |
A1 |
Diekevers; Mark S. ; et
al. |
August 2, 2012 |
Machine and Track Assembly For Use Therewith
Abstract
A track assembly for a machine includes a track having inner
track seals, a rotatable track engaging element such as an idler or
drive sprocket and a contact interface for protecting the seals
during guiding the track about the rotatable element. The contact
interface may include sacrificial wear material on the rotatable
element and sacrificial wear material on corresponding track links.
The contact interface may have a configuration based on a location
of the seals, and is adapted to inhibit wear of the track links in
regions adjacent the seals. In another aspect, the contact
interface is a guide interface.
Inventors: |
Diekevers; Mark S.;
(Metamora, IL) ; Clarke; Donovan S.; (Hanna City,
IL) ; Steiner; Kevin L.; (Tremont, IL) ;
Penrod; Victor M.; (Dunlap, IL) ; Recker; Roger
L.; (Dunlap, IL) |
Assignee: |
CATERPILLAR, INC.
Peoria
IL
|
Family ID: |
40221344 |
Appl. No.: |
13/443429 |
Filed: |
April 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12888542 |
Sep 23, 2010 |
8172342 |
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13443429 |
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11975206 |
Oct 18, 2007 |
8100483 |
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12888542 |
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Current U.S.
Class: |
305/137 |
Current CPC
Class: |
B62D 55/145 20130101;
B62D 55/21 20130101 |
Class at
Publication: |
305/137 |
International
Class: |
B62D 55/14 20060101
B62D055/14; B62D 55/20 20060101 B62D055/20 |
Claims
1. A rotatable track engaging idler, for guiding a ground engaging
track having first and second chain assemblies coupled together via
track pins received in bores formed in inboard track links of the
first and second chain assemblies, bushings positioned on the track
pins, and inner track seals positioned in the bores and being
adjacent to exposed seal regions of the inboard track links, the
rotatable track engaging idler comprising: a body defining an axis
of rotation and including an inner surface centered about the axis
of rotation, and a first and a second axial side surface facing
opposed axial directions and extending radially outward from the
inner surface to a first and a second corner of the body,
respectively; the body further including a guide element extending
circumferentially about the axis of rotation, and having a first
guide surface and a second guide surface, each positioned axially
between the first and second corners; the first and second guide
surfaces each having an orientation transverse to the axis of
rotation, such that contact between the first and second guide
surfaces and complementary guide surfaces formed on bushings of the
ground engaging track limits side to side movement of the idler
during guiding the ground engaging track to prevent contact between
the corners and the exposed seal regions.
2. The idler of claim 1 wherein the guide element is
circumferential of the axis of rotation.
3. The idler of claim 2 wherein the guide element projects in a
radially outward direction, and includes a plurality of radially
outermost points of the body.
4. The idler of claim 3 wherein the guide element has an axial
thickness equal to at least a majority of an axial thickness of the
body.
5. The idler of claim 4 wherein the first surface and the second
surface each have a sloping profile in a section plane which
includes the axis of rotation.
6. The idler of claim 5 wherein the guide element includes a crown
extending from the first corner to the second corner, and being
configured to mate with grooves comprising the complementary guide
elements.
7. The idler of claim 3 wherein the guide element has an axial
thickness equal to less than a majority of an axial thickness of
the body.
8. The idler of claim 7 wherein the seal protecting guide element
includes a tab configured to mate with slots comprising the
complementary guide elements.
9. A track assembly for a machine comprising: a ground engaging
track having a first chain assembly and a second chain assembly
coupled together via a plurality of track pins, and a plurality of
bushings positioned one upon each of the track pins; the first and
second chain assemblies each including a plurality of inboard track
links and a plurality of outboard track links, each of the inboard
track links having a bore formed therein and an exposed seal region
adjacent to the bore, and each of the plurality of track pins
including an inboard collar received within one of the bores, and
an inner track seal positioned within the inboard collar; a drive
sprocket; a rotatable track engaging idler in contact with at least
one of the bushings between the first and second chain assemblies,
the idler defining an axis of rotation, and including an inner
surface centered about the axis of rotation, and a first and a
second axial side surface facing opposed axial directions and
extending radially outward from the inner surface to a first and a
second corner of the body, respectively; and a guide limiting side
to side movement of the idler relative to the first and second
chain assemblies during guiding the ground engaging track, such
that contact between the corners and the exposed seal regions is
prevented.
10. The track assembly of claim 9 wherein each of the plurality of
bushings is rotatable about the corresponding track pin.
11. The track assembly of claim 10 wherein the idler includes a
first guide element, and each of the plurality of bushings includes
a complementary guide element, the first guide element and the
complementary guide elements together comprising the guide, and the
first guide element being mated with at least one of the
complementary guide elements.
12. The track assembly of claim 11 wherein the first guide element
is circumferential of the axis of rotation and projects in a
radially outward direction.
13. The track assembly of claim 12 wherein the first guide element
includes a first and a second guide surface, each having a sloping
profile in a section plane which includes the axis of rotation.
14. The track assembly of claim 13 wherein the first guide element
includes a crown, and the complementary guide elements each include
a groove formed in the corresponding bushing.
15. The track assembly of claim 12 wherein the first guide element
includes a tab, and the complementary guide elements each include a
slot formed in the corresponding bushing.
16. The track assembly of claim 9 wherein the guide includes a
first and a second end flange formed on each of the bushings and
positioned between the corners and the exposed seal regions when
the corresponding bushing is in contact with the idler.
17. The track assembly of claim 14 wherein the first and second end
flanges include a sacrificial wear material, and the idler includes
a hardened sacrificial wear material in corresponding
locations.
18. The track assembly of claim 15 wherein the inboard and outboard
links include straight links.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 12/888,542, now U.S. Pat. No. ______ filed
Sep. 23, 2010, which is a continuation of U.S. patent application
Ser. No. 11/975,206, filed Oct. 18, 2007, now U.S. Pat. No.
8,100,483.
TECHNICAL FIELD
[0002] The present disclosure relates generally to machine track,
and relates more particularly to a machine and associated track
assembly having a unique interface design between track assembly
components to protect inboard track seals from damage.
BACKGROUND
[0003] A wide variety of machines utilize tracks, commonly as
ground engaging propulsion elements, but also for other purposes
such as torque transmission and conveying. It is common for such
tracks to include a plurality of rotatable track engaging elements,
with the track forming an endless chain that is moved about the
rotating elements during operation. The demands placed upon such
machines and their associated track assemblies can be quite
substantial, and machine tracks are often relatively robust to
provide a long operating life despite significant mechanical
stresses, strain and wear experienced during operation.
[0004] One conventional track system known from track-type tractors
and the like utilizes one or more rotatable idlers which engage the
tracks, typically working in conjunction with a drive sprocket. The
idlers passively rotate to guide the associated track about a
desired path. It is common in conventional track systems for the
rotatable idler to roll against "rails" located on links of the
track chains. More recently, designs have been implemented in
certain machines where the rotatable idler and track are configured
such that the idler contacts the track between adjacent parallel
track chain assemblies, rather than riding on the rails.
[0005] One such design is known from U.S. Pat. No. 5,829,849 to
Lawson. In the Lawson strategy, an idler contacts roller bushings
located between track chain assemblies to support and guide the
track as it rotates to propel the machine. Tapered side portions of
the idler provide lateral guiding of the track chain assemblies.
Lawson overcomes certain design and operating issues associated
with conventional systems where the idler rides on rails. While
Lawson provides a successful strategy, there is always room for
improvement, particularly with regard to the wear characteristics
of the system.
[0006] The present disclosure is directed to one or more of the
problems or shortcomings set forth above.
SUMMARY
[0007] In one aspect, a track assembly for a machine includes a
track having a first chain assembly, a second chain assembly
coupled with the first chain assembly via a track pin, and a first
and second seal located within a first and second bore,
respectively, of track links of the first and second chain
assemblies. The track assembly further includes a rotatable track
engaging element configured to guide the track at least in part by
contacting the track between the chain assemblies, and a contact
interface between the rotatable track engaging element and the
track. The contact interface includes means, located on at least
one of the track and the rotatable track engaging element, for
inhibiting track link wear in regions adjacent the seals during
contacting the track with the rotatable track engaging element.
[0008] In another aspect, a machine includes a frame, and at least
one track coupled with the frame which includes a first chain
assembly and a second chain assembly, the chain assemblies each
including a plurality of track links and being coupled together via
a plurality of track pins. A plurality of seals are positioned
within bores in the track links, and the machine further includes a
rotatable track engaging element having an outer diameter
contacting the track between the first chain assembly and the
second chain assembly. The machine further includes a contact
interface between the rotatable track engaging element and the
track which includes a contact element on at least one of the track
and the rotatable track engaging element which is configured to
inhibit track link wear in regions adjacent to the seals during
contacting the track with the rotatable track engaging element.
[0009] In still another aspect, a method of protecting seals of a
machine track during operating the machine track includes the steps
of moving a machine track having first and second parallel chain
assemblies of track links about a rotatable track engaging element,
and guiding the machine track relative to the track engaging
element at least in part by contacting the track engaging element
with the track between the first and second chain assemblies. The
method further includes a step of, during guiding the machine
track, protecting inner track seals disposed within the track links
at least in part by inhibiting contact between the rotatable track
engaging element and regions of the track links adjacent the inner
track seals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side diagrammatic view of a portion of a machine
according to one embodiment;
[0011] FIG. 2 is a side elevational view of an idler according to
one embodiment;
[0012] FIG. 3 is a sectioned view taken along line 3-3 of FIG.
1;
[0013] FIG. 4 is a sectioned view taken along line 4-4 of FIG.
1;
[0014] FIG. 5 is a partial sectioned view taken along line 5-5 of
FIG. 1;
[0015] FIG. 6 is a partial sectioned view of a track assembly
according to one embodiment;
[0016] FIG. 7 is a partial sectioned view of the track assembly of
FIG. 6 taken in a different section plane;
[0017] FIG. 8 is a partial sectioned view of a track assembly
according to one embodiment;
[0018] FIG. 9 is a diagrammatic view of a portion of a track
assembly according to one embodiment;
[0019] FIG. 10 is a partial sectioned view of a track assembly
according to one embodiment;
[0020] FIG. 11 is a partial sectioned view of a track assembly
according to one embodiment; and
[0021] FIG. 12 is a partial sectioned view of a track assembly
according to one embodiment.
DETAILED DESCRIPTION
[0022] Referring to FIG. 1, there is shown a portion of a machine
10 according to the present disclosure. Machine 10 is shown in the
context of a track-type machine having a first ground engaging
track 16, mounted at a first side of a frame 12, and also including
a second ground engaging track identical to track 16 and positioned
at a second side of frame 12 but not visible in FIG. 1. Track 16
extends about a plurality of rotatable track engaging elements,
including an idler 20 having an axis of rotation A, a drive
sprocket 68 having an axis of rotation B and a plurality of track
rollers, one of which is shown and identified via reference numeral
26. Machine 10 may also include other rotatable track engaging
elements coupled with each of its one or more tracks such as an
additional idler. While only a single track is shown in FIG. 1, the
present description of track 16 and the track assembly 14 of which
it is a part should be understood to refer also to a second track
and associated track assembly of machine 10. While machine 10 may
be a track-type machine such as a track loader, excavator, tractor
or another mobile machine, the present disclosure is not thereby
limited. In other embodiments, track assembly 14 might comprise a
portion of a machine such as a conveyor. In all embodiments
contemplated herein, track assembly 14 will be configured such that
certain types of wear, in particular wear affecting track seals as
described hereinbelow, will be reduced or eliminated as compared
with conventional designs.
[0023] Track 16 will typically comprise two parallel track chain
assemblies, one of which is shown in FIG. 1 and identified with
reference numeral 18b, extending in parallel and coupled together
via a plurality of track pins 28. In the illustrated embodiment,
track chain assembly 18b consists of a plurality of straight
outboard track links 22 alternating with a plurality of straight
inboard track links 24, although other track configurations such as
those having S-shaped links or multi-piece link assemblies are
contemplated herein.
[0024] During moving track 16 about idler 20, inboard links 24 may
intermittently or continuously contact idler 20, guiding track 16
thereabout. Each inboard link 24 may have a contact length L with
idler 20, the significance of which will be apparent from the
following description. Links 24 will also tend to contact sprocket
68 during moving track 16 thereabout, and the present description
emphasizing idler 20 should be understood to be similarly
applicable to an interaction between sprocket 68 and track 16,
except as otherwise indicated. Referring also to FIG. 2, there is
shown a side view of idler 20 showing axis of rotation A, an outer
diameter 34 or outer diameter surface, which is positioned at a
constant radial distance from axis A, and an inner diameter 95 or
inner diameter surface. In the embodiment shown, outer diameter 34
is configured to contact track 16 between its respective chain
assemblies, in particular contacting track pins 28, or rotating
bushings positioned on track pins 28, as further described herein.
In other embodiments, a different engagement strategy between track
16 and idler 20 might be used, for example, a sprocketed idler
could be used. Idler 20 further includes a step 32 spaced radially
inwardly of outer diameter 34 and separated from outer diameter 34
via a transition surface 33 which is an outboard surface.
Transition surface 33 extends a first radial distance from a seal
protecting wear surface 43b to outer diameter 34. An inboard
surface 97 extends a second, greater radial distance from seal
protecting wear surface 43b to inner diameter 95. In connection
with idler 20, the terms "inboard" and "outboard" mean,
respectively, toward inner diameter 95 and away from outer diameter
34, and toward outer diameter 34 and away from inner diameter 95.
Step 32 extends/protrudes axially from an axial side 30 of idler
20, axial side 30 extending in a radial direction from inner
diameter 95 to outer diameter 34. Step 32 assists in mitigating
wear in track assembly 14 during operation, as further described
herein. It may further be noted from FIG. 2 that step 32 includes
concentric radially inward and radially outward step edges 103 and
101, respectively, which each define a circle centered on axis A,
and that transition surface 33 adjoins outer diameter 34 at a
corner 100. An opposite axial side of idler 20 is not visible in
FIG. 2, but will typically be substantially identical to axial side
30.
[0025] Referring now to FIG. 3, there is shown a sectioned view
taken along line 3-3 of FIG. 1. As illustrated in FIG. 3, outer
diameter 34 of idler 20 contacts a rotating bushing 25 positioned
about pin 28. In the illustrated embodiment, pin 28 comprises a
cartridge pin having a fluid cavity 39 sealed via a plug 47. Pin 28
may further include inboard collars 50 positioned on opposite sides
of rotating bushing 25, and outboard collars 52 positioned outboard
of each inboard collar 50, and coupled with pin 28 via any suitable
means such as snap rings or the like. In other embodiments, a pin
configuration or a pin assembly different from that illustrated in
FIG. 3 might be used, such as a pin having an integral bushing, or
a pin assembly other than a cartridge pin. Track chain assembly
18b, including an inboard link 24b and an outboard link 22b is
positioned on pin 28, as is another track chain assembly 18a, also
including an inboard link 24a and an outboard link 22a. Each of
inboard links 24a and 24b includes a bore 46a and 46b,
respectively, which is typically press fit with inboard collars 50.
A first inner track seal 54a and a second inner track seal 54b are
positioned within collars 50, and thus positioned within bores 46a
and 46b, respectively. Exposed seal regions 105 of links 24a and
24b face a track guiding space 107. Lubricating fluid from cavity
39 may be distributed to various of the components of track 16, and
fluidly sealed from escaping via seals 54a and 54b, and such other
seals as may be used in conjunction with outboard collars 52. Each
of track chain assemblies 18a and 18b may further include a rail 23
upon which other rotatable track engaging elements such as track
roller 26 ride during operation.
[0026] It has been discovered that in certain conventional track
assembly designs, rotatable components such as idlers and drive
sprockets can have a tendency to wear away material from inboard
track links, eventually exposing and damaging inboard track seals
and causing leaks of lubricating fluid, as well as potentially
damaging the track. This phenomenon tends to result at least in
part from the shape of the track assembly components in regions
where they have a tendency to contact one another. The present
disclosure provides unique strategies for inhibiting this type of
wear, and in particular includes a first contact interface 40a and
a second contact interface 40b, which inhibit track link wear in
regions of the track links adjacent seals 54a and 54b.
[0027] In one embodiment, seals 54a and 54b may be protected from
wear-related damage at least in part by placing seals 54a and 54b
within recesses 60 of contact interfaces 40a and 40b. It may be
noted from FIG. 3 that ends of roller bushing 25 extend into
recesses 60 in links 24a and 24b. The illustrated configuration can
assist in inhibiting wear of regions of track links 24a and 24b
adjacent seals 54a and 54b, respectively, by positioning seals 54a
and 54b relatively further from idler 20. It should be appreciated
that over the course of many hours of operation, components such as
bushing 25 can wear away, such that idler 20 can actually migrate
closer to seals 54a and 54b than that which is shown in FIG. 3.
Recessing seals 54a and 54b can prevent or delay a time at which
idler 20 wears material of links 24a and 24b and begins to impinge
on seals 54a and 54b. Moreover, in some embodiments using recesses
60 to protect seals 54a and 54b may be the sole means for
inhibiting track link wear in regions adjacent thereto, whereas in
other embodiments recesses 60 might be used in conjunction with
other means for inhibiting track link wear, or might not be used at
all.
[0028] In certain embodiments, with or without using recesses 60,
contact interfaces 40a and 40b may be understood as "wear"
interfaces which direct wear between element 20 and chain
assemblies 18a and 18b predominantly to areas of links 24a, 24b
other than regions adjacent track seals 54a and 54b. For example,
regions of track links 24a and 24b where recesses 60 are disposed
in the FIG. 3 version may be understood as "adjacent to" seals 54a
and 54b as the term "adjacent to" is intended to be understood
herein. In other embodiments, described hereinbelow, contact
interfaces of a track assembly may comprise guide interfaces,
which, rather than directing wear, inhibit or limit certain types
of contact between the respective components in the first place. By
designing track assembly 14 in the manner described herein, wear on
inboard track links 24a and 24b in regions adjacent seals 54a and
54b, respectively, can be reduced or eliminated as compared with
conventional designs. In one embodiment, each contact interface 40a
and 40b may include sacrificial wear material 42a and 42b,
respectively, located on idler 20, as well as sacrificial wear
material 44a and 44b located on inboard track links 24a and 24b,
respectively. In other embodiments, sacrificial wear material might
be located on only one of track 16 and element 20. As mentioned
above, idler 20 may include a step 32b on a first axial side 30,
and another step 32a on an opposite axial side 31, comprising
portions of contact interfaces 40a and 40b. Each of steps 32a and
32b may protrude in axial directions relative to sides 31 and 30,
respectively, and be spaced radially inwardly of outer diameter
34.
[0029] In one embodiment, each of contact interfaces 40a and 40b
may comprise a first planar face 43a and a second planar face 43b
located on steps 32a and 32b, respectively, each of which comprises
a seal protecting wear surface also identified via reference
numerals 43a and 43b, and including wear material 42a and 42b.
Contact interfaces 40a and 40b may also include a third planar face
45a and a fourth planar face 45b located on track links 24a and 24b
and including sacrificial wear material 44a and 44b, respectively.
Planar faces 43a, 43b, 45a and 45b may be oriented perpendicular
axis A of idler 20 such that a contact length L between links 24a
and 24b and idler 20 comprises a planar interface. The respective
planar faces of the wear interfaces may face toward one another, in
opposed directions, at all locations where idler 20 and links 24a
and 24b may come into contact during operation, and may be
parallel. This configuration can eliminate or reduce contact
between edges or corners of idler 20 and portions of links 24a and
24b, as may occur where an idler having tapered axial surfaces is
used. In other embodiments, certain of which are described herein,
non-planar faces of wear material may be used.
[0030] In one embodiment, wear material 42a and 42b and wear
material 44a and 44b may consist of hardened forged or cast
material of idler 20 and inboard track links 24a and 24b,
respectively. Wear material 42a, 42b, 44a and 44b may consist of
the forged material of the respective components which is hardened
by heat treating. In other embodiments, induction hardening,
coatings or some other hardening strategy might be used. In FIG. 3,
reference numeral 45 identifies forged material of inboard track
links 24a and 24b. It will often, though not necessarily, be
desirable to avoid hardening material of inboard track links 24a
and 24b in regions where bores 46a and 46b are located, to avoid
interfering with press fits with inboard inserts 50. To this end,
unhardened material 45 of each link 24a and 24b may define bores
46a and 46b.
[0031] Turning now to FIG. 5, there is shown a partial sectioned
view taken along line 5-5 of FIG. 1. As mentioned above, drive
sprocket 68 may have a configuration having certain similarities
with that of idler 20 to address similar wear concerns with respect
to track 16. Sprocket 68 may include a plurality of outer track
contacting segments 70, one of which is shown, each including a
plurality of teeth 72 alternating with a plurality of pockets 74.
It should be appreciated that in the FIG. 5 illustration, tooth 72
is positioned forwardly of the section plane and is therefore shown
in phantom. It may also be noted from FIG. 5 that pocket 74 engages
with rotating bushing 25 between the respective track chain
assemblies.
[0032] A first contact interface 140a and a second contact
interface 140b may be positioned on opposite axial sides of
sprocket 68, and each may include wear material 80a and 80b located
on sprocket 68 and wear material 44a and 44b located on inboard
track links 24a and 24b. Interfaces 140a and 140b may each have a
configuration based at least in part on a location of seals 54a and
54b within their corresponding track links, similar to wear
interfaces 40a and 40b associated with idler 20. In other words, by
providing a particular shape for the interfacing components, based
on a location of the seals to be protected, wear can predominantly
occur in regions not adjacent to the subject seals. For instance,
in the case of sprocket 68 and idler 20, they are each configured
via wear interfaces having wear material of an appropriate shape
and location such that material is worn away from links 24a and 24b
predominantly in regions relatively closer to rails 23, avoiding
wear relatively closer to seals 54a and 54b.
[0033] "Guide" interfaces, as further described herein, may also be
used in connection with sprocket 68, rather than the illustrated
wear features. In one embodiment, sprocket 68 may include a hub
portion 76 having track contacting segment 70 coupled therewith via
a plurality of bolts 82. In other embodiments, rather than plural
track contacting segments, sprocket 68 might consist of a single
cast or forged piece, or one track contacting portion coupled with
a separate hub portion. A nut strip 78 or the like may be provided
which receives a threaded end of each of bolts 82. In FIG. 5, nut
strip 78 is shown diagrammatically as a single piece, but may
include a plurality of segments corresponding to a plurality of
track contacting segments 70. In one embodiment, wear material 80a
may be positioned on nut strip 78, at a first axial side of
sprocket 68, whereas other wear material 80b may be positioned on
an opposite axial side of sprocket 68, comprising a portion of
segment 70. It will be noted that the configuration of nut strip 78
and segment 70 is at least generally analogous to steps 32a and 32b
of idler 20, each of elements 78 and 70 having a planar face 143a
and 143b which comprises a portion of the corresponding contact
interface 140a and 140b, respectively.
[0034] Turning now to FIG. 6, there is shown a track assembly 214
according to yet another embodiment. Track assembly 214 includes a
rotatable track engaging element 220, such as an idler, having a
first axial side 231 and a second axial side 230. Rotatable track
engaging element 220 is configured to contact a track 216 between a
first track chain assembly 218a and a second track chain assembly
218b. Track assembly 214 further includes a first contact interface
240a between element 220 and chain assembly 218a, and a second
contact interface 240b between element 220 and track chain assembly
218b. Contact interfaces 240a and 240b may include a first step
232a and a second step 232b, respectively, positioned to extend
from first and second axial sides 231 and 230 and spaced radially
inward of an outer diameter 234 of element 220, and each including
sacrificial wear material thereon. The embodiment shown in FIG. 6
has certain similarities with previously described embodiments, in
that contact interfaces 240a and 240b may comprise wear interfaces
whereby damage to inner track seals 54a and 54b is inhibited via
the proper placement of wear material, having an appropriate shape,
which is based at least in part on a location of track seals 54a
and 54b within their corresponding track links. In other words,
like the embodiment of FIG. 3 the embodiment shown in FIG. 6 can
include sacrificial wear material which wears away as track chain
assemblies 218a and 218b are moved about element 220, avoiding wear
in regions of the corresponding track links adjacent track seals
54a and 54b. In one embodiment, each of steps 232a and 232b may
have a conical face 243a and 243b, respectively, which includes
sacrificial wear material, whereas each of the inboard track links
224 may include an opposed face 245a and 245b, respectively, which
is configured to contact faces 243a and 243b, respectively, during
operation of track assembly 214.
[0035] Track assembly 214 differs from track assembly 14 described
above in that, rather than each contact interface including an
interface of planar surfaces, faces 243a and 243b may be conical,
and disposed at an angle relative to an axis of rotation of element
220, rather than being perpendicular thereto as in track assembly
14. Faces 245a and 245b may be conical, planar or some other
configuration. Referring also to FIG. 7, there is shown a sectioned
view of track assembly 214 taken in a different section plane, at a
location spaced from pin 28 in contrast to FIG. 6 which is
sectioned approximately through the middle of pin 28.
[0036] Referring now to FIG. 8, there is shown another track
assembly 314. It should be appreciated that track assembly 314
might be used with or comprise a part of one of the other track
assemblies described herein, and is thus not necessarily a separate
system. Track assembly 314 may include a rotatable track engaging
element 368, such as a drive sprocket, having a flange 376 which is
coupled with at least one track contacting segment 370 having
alternating teeth 372 and pockets 374. Sprocket 368 operates
generally in a manner similar to that described above with regard
to the embodiment of FIG. 5, but has certain differences. Sprocket
368 is configured to engage with a track having a first track chain
assembly 318a and a second track chain assembly 318b, and contacts
the corresponding track between chain assemblies 318a and 318b,
track contact segment 370 functioning in a manner similar to that
of the embodiment of FIG. 5 to apply driving force to the
associated track. A nut strip 378 may be bolted to flange 376, and
in certain embodiments could include a plurality of separate nut
strips. Nut strip 378 comprises a portion of a contact interface
340 between drive sprocket 368 and chain assemblies 318a and 318b.
In contrast to the embodiment of FIG. 5, nut strip 378 may include
a conical face 343 which is configured to contact another face 345
on links of chain assembly 318b. An additional contact interface
having a configuration similar to that of interface 340, to protect
seals within track chain assembly 318a, might be located on a side
of sprocket 368 opposite that of interface 340 in certain
embodiments.
[0037] Referring to FIG. 9, there is shown a diagrammatic view of a
track contacting segment 470 suitable for use with a track engaging
element such as a toothed idler or drive sprocket. Track contacting
segment 470 may include an arcuate body 471 having a plurality of
teeth 472 alternating with pockets 474, and is configured to engage
with a track in a conventional manner. Arcuate body 471 further
includes an outer diameter surface 434, an inner diameter surface
431 defining a segment of a circle C having a center axis Z, a
first axial side 430, a second axial side 431, and a plurality of
apertures 440 communicating between axial sides 430 and 431. An
outboard axial surface 433 is shown located on axial side 430 in
FIG. 9. Track contacting segment 470 further includes a contact
interface 440 which comprises a discontinuous contact interface
wherein faces of wear material 432 are spaced apart rather than
consisting of a continuous step or the like. Identical wear
material faces 432 may be located upon axially projecting steps
439, and spaced apart in an arcuate configuration as shown. The
spacing between the faces of wear material 432 may be used to
access bolts, etc. received in apertures 440 for coupling segment
470 with a hub component, etc. as will be readily apparent to those
of skill in the art.
[0038] Referring now to FIG. 10, there is shown a sectioned view of
yet another track assembly 514. Track assembly 514 may include a
rotatable track engaging element 520, such as an idler or possibly
a drive sprocket, configured to engage with a track having a first
chain assembly 518a and a second chain assembly 518b, each of which
includes a plurality of inner track seals 54a and 54b. Track
assembly 514 is an example of a track assembly according to the
present disclosure wherein rather than a contact interface which
comprises a wear interface to direct wear between the respective
components, the contact interface 540 of track assembly 514
comprises a guide interface wherein contact between rotatable track
engaging element 520 and track links of chain assemblies 518a and
518b is inhibited or avoided altogether, to protect inner track
seals 54a and 54b. Any of the "guide" interface embodiments
described herein might be used also with "wear" interfaces if
desired. In one embodiment, contact interface 540 may include a
first guide element 534 on rotatable track engaging element 520,
and a second guide element 535 complementary to guide element 534
which is located on a roller bushing 525. In the embodiment shown,
track engaging element 520 includes a crown 534 which fits within a
complementary groove 535 formed in roller bushing 525. Accordingly,
during operation of track assembly 514 rotatable track engaging
element 520 and track chain assemblies 518a and 518b are maintained
in a state at which contact between axial sides or corners of track
engaging element 520 and inboard track links 524 is limited or
avoided, as interaction between crown 534 and element 535 tends to
keep element 520 from moving laterally toward either of chain
assemblies 518a and 518b. In a related embodiment, the
configuration of the components of contact interface 540 might be
reversed. In other words, roller bushing 525 could include a crown,
and track engaging element 520 could include a groove.
[0039] Turning to FIG. 11, there is shown yet another track
assembly 614 according to the present disclosure. Similar to the
embodiment shown in FIG. 10, track assembly 614 includes a contact
interface 640 wherein, rather than directing wear between
components, wear is avoided by inhibiting or eliminating contact
between certain of the components. In particular, a rotatable track
engaging element 620 is provided which includes a tab or ridge 636
formed on an outer diameter 634 thereof. Tab 636 will typically be
circumferential of outer diameter 634 and may fit within a slot 635
formed in a roller bushing 625, such that side to side movement of
element 620 relative to a first track chain 618a and a second track
chain 618b is limited, reducing or eliminating a tendency for
rotatable track engaging element 620 to contact inner track links
624 in regions adjacent inner track seals 54a and 54b. Contact
interface 640 might also be reversed, such that slot 635 is in
element 620 and tab 636 is formed on roller bushing 625.
[0040] Turning now to FIG. 12, there is shown still another track
assembly 714 according to the present disclosure. Track assembly
714 also includes a rotatable track engaging element 720 having an
outer diameter 734. Outer diameter 734 contacts a roller bushing
725 positioned between a first chain assembly 718a and a second
chain assembly 718b. Track assembly 714 further includes contact
interfaces 740a and 740b. In the embodiment shown in FIG. 12, each
of contact interfaces 740a and 740b includes a flange 726a and 726b
located at each end of roller bushing 725. During operation,
flanges 726a and 726b may inhibit or eliminate contact between
track engaging elements 720 and inboard track links 724 in regions
where track seals 54a and 54b are located, as flanges 726a and 726b
are positioned inboard of track seals 54a and 54b and between links
724 and element 720. Flanges 726a and 726b could also comprise
sacrificial wear material, such as hardened material, which wears
away via contact with element 720.
INDUSTRIAL APPLICABILITY
[0041] Referring to FIGS. 1-5, the portions of contact interfaces
40a and 40b located on idler 20, e.g. steps 32a and 32b and the
corresponding wear material 42a and 42b, are generally uniform
about idler 20, having a generally circular configuration and
extending inwardly from outer diameter 34, curving into and out of
the page in the FIG. 3 illustration. The portions of wear
interfaces 140a and 140b located on sprocket 68 may have an
analogous configuration. The following description of idler 20 in
conjunction with track 16 may thus be understood to refer to
sprocket 68, except where otherwise noted. The portions of contact
interfaces 40a and 40b located on links 24a and 24b and the
corresponding wear material 44a and 44b generally have a linear
configuration, extending perpendicular to and in and out of the
page in FIG. 3. As a result, the interface between wear material
42a and 42b on idler 20 and wear material 44a and 44b is different
at different locations along the contact length L, given the
interface of a curving component, idler 20, with straight links 24a
and 24b.
[0042] FIG. 3 illustrates the relative location of the respective
planar faces of each wear interface 40a and 40b at one location
along contact length L, i.e. at pin 28. Referring to FIG. 4, there
is shown a partially sectioned view taken along line 4-4 of FIG. 1.
FIG. 4 illustrates the differing relative locations of faces 45a
and 43a, and 45b and 43b at a location spaced from pin 28 along
contact length L. This configuration differs from that of certain
earlier designs wherein at certain points along a contact length
between track links and an idler, corners of the idler impinged
upon surfaces of the track links in regions adjacent the track
seals. As a consequence, the sharp idler corners had a certain
tendency to wear away link material more quickly than desired, at
least in certain instances. The present disclosure overcomes such
wear issues by providing a different type of contact interface
altogether, with hardened material placed in different locations
and having a different shape than that of earlier strategies. It
may also be noted from FIGS. 3 and 4 that surface 97 and a
counterpart surface 49 on axial side 31 each include a lower axial
elevation and a lower material hardness, surface 33 and a
counterpart surface 35 on axial side 31 each include a middle axial
elevation and a higher material hardness, and surfaces 43a and 43b
each include a higher axial elevation and a higher material
hardness. Idler 20 also includes a lesser axial thickness between
surfaces 97 and 49, a medium axial thickness between surfaces 33
and 35, and a greater axial thickness between surfaces 43a and
43b.
[0043] It should be appreciated that idler 20 will typically have
an axial thickness between planar faces 43a and 43b which is
slightly less than a distance between planar faces 45a and 45b. As
a result, idler 20 may alternately contact links 24a and 24b during
moving track 16 into engagement with, rotating about, and
disengaging from idler 20, the alternating contact serving to guide
track 16 laterally with respect to idler 20. In other words, track
16 may move back and forth relative to idler 20, resulting in
alternate contact therebetween at contact interfaces 40a and 40b.
Relative movement of links 24a and 24b as the subject portion of
track 16 moves into engagement with idler 20 can also result in
sliding contact at contact interfaces 40a and 40b as outer diameter
34 moves toward or away from bushing 25 during engagement or
disengagement, respectively, of a given portion of track 16 with
idler 20. Each of these types of contact between the respective
faces of wear interfaces 40a and 40b can, and is intended to, wear
away wear material 42a and 42b and 44a and 44b. Outer diameter 34
will also wear due to its engagement with bushing 25, often
increasing the total contact area at interfaces 40a and 40b as
steps 32a and 32b migrate relatively closer to outer diameter 34
due to loss of material from outer diameter 34. In the case of
sprocket 68, wear will take place in an analogous manner,
simultaneously wearing material 44a and 44b from links 24a and 24b,
and wearing material 80a and 80b from sprocket 68.
[0044] Returning to FIG. 5, it may further be noted that bushing 25
extends into recess 60. An end of bushing 25 within recess 60 of
inboard track link 24a lies in a plane A. Plane A also extends
approximately along/through an inboard edge of seal 54a. Plane A is
spaced from another plane O positioned inboard of plane A. The
terms "inboard" and "outboard" as used herein in describing planes
A and O will be understood to have meanings familiar to those
skilled in the art of machine track, i.e. inboard means toward a
center of track 16 between its track chain assemblies, in other
words toward a longitudinal midpoint of pin 28, whereas outboard
means away from the center of track 16 and toward lateral sides of
track 16, in other words toward terminal ends of pin 28. Plane O
lies approximately at an outboard end of recess 60, and is in turn
spaced inboard from yet another plane B which is defined by planar
face 45a. Planar face 143a of nut strip 78 also defines a plane,
plane C, which is spaced slightly inboard of plane B but will
typically move relative thereto with side to side motion of
sprocket 68 between track chain assemblies 18a and 18b. FIG. 5
illustrates certain of the design attributes of the present
disclosure via the illustration of planes A, B, C and O whereby
seals 54a and 54b, of each of the inboard links 24a and 24b of
track 16 can be protected from wear during track operation. It
should be appreciated that idler 20 has analogous features and wear
characteristics with regard to protecting seals 54a and 54b, as its
interaction with track 16 will be similar to the interaction of
sprocket 68 therewith. In other words, the present description of
planes A, B, C and O may be understood to refer to corresponding
features of idler 20.
[0045] The separation of plane A from plane O, and the separation
of plane O from plane B positions seal 54a sufficiently away from
wear interface 140a that any tendency for sprocket 68 to wear away
link material in a region of link 24a adjacent seal 54a is much
reduced or eliminated as compared with earlier designs. In other
words, for link 24a to begin to wear adjacent seal 54a, hardened
wear material 44a would need to be worn away such that planes B and
O are no longer separated. Then, additional material would need to
be worn away such that planes O and A are no longer separated. The
relative distances separating the respective planes may be chosen
such that seal service life is not a limiting factor in track
service life. The shape of the components defining the wear
interfaces described herein further reduces the wear rates as
compared with earlier designs, as planar wear interfaces 40a, 40b,
140a, and 140b may wear more slowly than interfaces wherein angled,
or otherwise non-planar interfaces between components are used.
Moreover, hardened material abuts and wears against hardened
material at the wear interfaces, in contrast to earlier strategies
wherein unhardened material was subjected to wear.
[0046] In view of the foregoing, it will be appreciated that the
unique configuration, location and composition of contact
interfaces 40a, 40b, 140a and 140b ensures that wearing of idler
20, sprocket 68 and track links 24a and 24b occurs in a manner that
protects seals 54a and 54b. In other words, by selecting an
appropriate shape for the relevant parts of idler 20, sprocket 68
and links 24a and 24b, wear of links 24a and 24b will predominantly
take place in regions not adjacent to seals 54a and 54b. Rather,
links 24a and 24b will have a tendency to wear at planar faces 45a
and 45b. This strategy contrasts with earlier designs, discussed
above, wherein contact interfaces between the respective components
had neither a shape nor other attributes that specifically
accounted for the location of the inboard track seals, and
consequently wear of inboard track links from contact with other
track components had a tendency to take place in regions close to
the inboard track seals, ultimately risking or causing seal damage
and leakage.
[0047] The embodiments of FIGS. 6 and 7 will have a tendency to
operate in a manner similar to that described with regard to the
embodiments of FIGS. 1-5. In some instances, the embodiment of
FIGS. 6 and 7 will be well suited to use with existing track
configurations, except for relatively minor differences. In other
words, the configuration of rotatable track engaging element 220 is
such that it may be used with track chain assemblies having
components sized and shaped similar to that of existing designs,
without the need for reconfiguring link shape, length, etc. The
embodiment shown in FIG. 8 has similar applicability to certain
existing track designs. With regard to the FIG. 9 embodiment, it
too will operate similarly to that of the embodiments of FIGS. 1-5,
however, rather than wear occurring along a continuous contact
interface, other intermittently spaced elements of contact
interface 440 will wear during track assembly operation.
[0048] As discussed above, each of the embodiments of FIGS. 10 and
11 may rely at least in part upon guiding between the rotatable
track engaging element 520, 620, and the associated track chain
assemblies 518a and 518b, and 618a and 618b, respectively. In other
words, rather than directing wear to particular regions of the
track links, contact between the respective components is limited
in the first place. The embodiment of FIG. 12 can function to
protect track seals 54a and 54b in a manner that relies upon both
guiding between the components and sacrificial wear material. In
one embodiment, flanges 726a and 726b may include sacrificial wear
material, and rotatable track engaging element 720 may also include
sacrificial wear material in corresponding locations. During
operation of track assembly 714, wear between flanges 726a and 726b
and element 720 can prevent wear of inboard track links 724 in
regions adjacent seals 54a and 54b. In addition, flanges 726a and
726b may assist in guiding element 720 to reduce or eliminate the
tendency for element 720 to contact links 724.
[0049] The present disclosure thus provides a number of different
ways of addressing certain wear issues in track assemblies. It
should be appreciated that many of the features of the various
embodiments could be combined in a single track assembly. Moreover,
many of the specific features disclosed herein might be omitted
from a track assembly design without departing from the scope of
the present disclosure. It should further be appreciated that the
specific geometry of the various contact interface designs might be
changed substantially. For example, rather than steps 32a and 32b
having the illustrated configuration, they might have a rounded
shape. Further still, the shapes of, and interaction between,
components may vary over time as material is worn away, while still
providing protection for seals 54a and 54b.
[0050] 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.
* * * * *