U.S. patent application number 12/796910 was filed with the patent office on 2011-12-15 for undercarriage for a tracked vehicle.
Invention is credited to Ronald Hall.
Application Number | 20110303470 12/796910 |
Document ID | / |
Family ID | 45095323 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110303470 |
Kind Code |
A1 |
Hall; Ronald |
December 15, 2011 |
UNDERCARRIAGE FOR A TRACKED VEHICLE
Abstract
In a first aspect, the invention is directed to an undercarriage
for a tracked vehicle. The undercarriage includes a main frame
including a frame body and an equalizer bar extending laterally on
either side of a pivot connection with the frame body, a first
track frame and a second track frame. A first front spherical
bearing connects a first end of the equalizer bar and the front end
of the first track frame. A second front spherical bearing connects
a second end of the equalizer bar and the front end of the second
track frame. A first rear spherical bearing connects the rear end
of the main frame to the rear end of the first track frame. A
second rear spherical bearing connects the rear end of the main
frame to the rear end of the second track frame. The spherical
bearings between the rear end of the main frame and the rear ends
of the track frames permit the rear ends of the track frames to
accommodate the arcuate movement of the front ends of the track
frames as the equalizer bar pivots about its pivot connection when
the vehicle travels over uneven terrain. The spherical bearings
further on both the front and the rear of the vehicle also permit
the tracks of the vehicle to more fully contact the ground when the
ground is not perfectly flat. An example of such a situation may be
when the vehicle travels on a road which is crowned.
Inventors: |
Hall; Ronald; (Woodstock,
CA) |
Family ID: |
45095323 |
Appl. No.: |
12/796910 |
Filed: |
June 9, 2010 |
Current U.S.
Class: |
180/9.1 |
Current CPC
Class: |
B62D 55/0842
20130101 |
Class at
Publication: |
180/9.1 |
International
Class: |
B62D 55/00 20060101
B62D055/00 |
Claims
1. An undercarriage for a tracked vehicle, comprising: a main frame
having a front end and a rear end and defining a longitudinal axis
and including a frame body having a front end and a rear end, and
an equalizer bar extending laterally and having a first end and a
second end, wherein the equalizer bar is mounted proximate the
front of the frame body for rotation about a longitudinally
extending equalizer bar pivot axis that is approximately centered
laterally between the first and second ends of the equalizer bar; a
first track frame and a second track frame each having a front end
and a rear end; a first front spherical bearing connecting the
first end of the equalizer bar and the front end of the first track
frame; a second front spherical bearing connecting the second end
of the equalizer bar and the front end of the second track frame; a
first rear spherical bearing connecting the rear end of the main
frame to the rear end of the first track frame; and a second rear
spherical bearing connecting the rear end of the main frame to the
rear end of the second track frame.
2. An undercarriage as claimed in claim 1, wherein each track frame
has a center of mass, and wherein each spherical bearing has a
center of rotation, wherein an axis of rotation for each track
frame extends between the centers of rotation of the front
spherical bearing and rear spherical bearing associated with each
track frame, wherein the center of mass of each track frame has
approximately the same lateral position as the axis of rotation for
each track frame.
3. An undercarriage as claimed in claim 2, wherein the center of
mass of each track frame has approximately the same vertical
position as the axis of rotation for each track frame.
4. An undercarriage as claimed in claim 1, further comprising at
least one first limit member and at least one second limit member
associated with each track frame, wherein the at least one first
and the at least one second limit members are positioned to limit
the range of angular rotation available to the track frame.
5. An undercarriage as claimed in claim 4, wherein the positions of
the at least one first limit member and the at least one second
limit member are selected based at least in part on the position of
the center of gravity of the tracked vehicle.
6. An undercarriage as claimed in claim 1, wherein each spherical
bearing has a bearing pass-through aperture that extends laterally,
and wherein one of the spherical bearings is supported at the front
and rear ends of each track frame and wherein a front bearing
mounting shaft extends laterally from each end of the equalizer bar
and passes through the bearing pass-through aperture of each of the
front spherical bearings, and wherein a rear bearing mounting shaft
extends laterally from each side of the rear end of the main frame
and passes through the bearing pass-through aperture of each of the
rear spherical bearings.
7. An undercarriage as claimed in claim 6, wherein each spherical
bearing is held in a pillow block which is mounted to one of the
track frames.
8. An undercarriage as claimed in claim 6, wherein each spherical
bearing is held in a pillow block which is removably fastened to
one of the track frames.
9. An undercarriage as claimed in claim 1, wherein each front
spherical bearing has a bearing pass-through aperture that extends
vertically, and wherein a front bearing mounting shaft extends
upwards from the front end of each track frame and passes through
the bearing pass-through aperture on one of the front spherical
bearings.
10. An undercarriage as claimed in claim 1, wherein the equalizer
bar is a front equalizer bar and wherein the undercarriage further
comprises a rear equalizer bar extending laterally and having a
first end and a second end, wherein the equalizer is mounted to the
rear of the frame body for rotation about a longitudinally
extending rear equalizer bar pivot axis that is approximately
centered laterally between the first and second ends of the rear
equalizer bar.
11. An undercarriage as claimed in claim 1, wherein each spherical
bearing is made up of a cast ball trunnion and a cast ball trunnion
support member.
12. An undercarriage as claimed in claim 1, wherein each spherical
bearing is made up of a cast steel ball trunnion extending
laterally from the main frame or from the equalizer bar and a cast
steel ball trunnion support member mounted one of the track frames,
wherein the cast steel ball trunnion is supported on the cast steel
ball trunnion support member and in use is movable relative to the
cast steel ball trunnion support member without an externally
supplied lubricant.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to tracked vehicles and more
particularly to tracked vehicles that have an undercarriage that
incorporates an equalizer bar.
BACKGROUND OF THE INVENTION
[0002] Tracked vehicles are in widespread use in several
industries, such as construction and farming to name but a few.
These vehicles are typically used on terrain that is uneven. These
vehicles often include an undercarriage that permits the left and
right track assemblies to accommodate the unevenness of the
terrain. For example, the main frame of the undercarriage may
include a laterally extending equalizer bar at the front which
pivots relative to the rest of the undercarriage and which is
connected at its ends to the fronts of the track frames. The
equalizer bar permits the fronts of the left and right track frames
to rise and drop relative to the main frame. Typically, there is no
equalizer bar at the rear of the main frame, however and so the
rears of the track frames are connected to the main frame via a pin
joint. The pin joints permit the rears of the track frames to pivot
as necessary while the fronts of the track frames to rise and drop.
It has been found, however, that the pin joints are prone to
seizing and to inhibit this, they are typically manufactured with a
lot of play in them. This play, however, can contribute to
premature wear in the rear joints, and so the rear joints can in
some cases require frequent and expensive maintenance.
[0003] It would be advantageous to provide an undercarriage for a
tracked vehicle that at least partially overcame the aforementioned
problem.
SUMMARY OF THE INVENTION
[0004] In a first aspect, the invention is directed to an
undercarriage for a tracked vehicle. The undercarriage includes a
main frame including a frame body and an equalizer bar extending
laterally on either side of a pivot connection with the frame body,
a first track frame and a second track frame. A first front
spherical bearing connects a first end of the equalizer bar and the
front end of the first track frame. A second front spherical
bearing connects a second end of the equalizer bar and the front
end of the second track frame. A first rear spherical bearing
connects the rear end of the main frame to the rear end of the
first track frame. A second rear spherical bearing connects the
rear end of the main frame to the rear end of the second track,
frame. The spherical bearings between the rear end of the main
frame and the rear ends of the track frames permit the rear ends of
the track frames to accommodate the arcuate movement of the front
ends of the track frames as the equalizer bar pivots about its
pivot connection when the vehicle travels over uneven terrain. The
spherical bearings further on both the front and the rear of the
vehicle also permit the tracks of the vehicle to more fully contact
the ground when the ground is not perfectly flat. An example of
such a situation may be when the vehicle travels on a road which is
crowned.
[0005] In a preferred embodiment, the equalizer bar is a front
equalizer bar and the main frame further includes a rear equalizer
bar, which extends laterally on either side of another pivot
connection with the main frame. The rear spherical bearings connect
between the rear equalizer bar and the track frames.
[0006] In a preferred embodiment (with or without the rear
equalizer bar), the spherical bearings are made from cast steel
ball trunnions which extend laterally from the main frame, and cast
steel ball trunnion support members which extend vertical and which
support the cast steel ball trunnions. Such an arrangement is
particularly advantageous in that it has been found that they do
not require externally provided lubrication (eg. grease or oil) in
order to operate. During use, they can pivot as necessary for
operation of the tracked vehicle without such lubrication, which
eliminates a maintenance task in respect of keeping the tracked
vehicle in good operating condition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The present invention will now be described by way of
example only with reference to the attached drawings, in which:
[0008] FIG. 1 is a perspective view of a tracked vehicle with an
undercarriage in accordance with an embodiment of the present
invention;
[0009] FIG. 2a is a perspective view of one side of the
undercarriage shown in FIG. 1;
[0010] FIG. 2a is a perspective view of the other side of the
undercarriage shown in FIG. 1;
[0011] FIG. 3 is a front elevation view of the undercarriage shown
in FIG. 1;
[0012] FIG. 4 is a front elevation view of an equalizer bar that is
part of the undercarriage shown in FIG. 1;
[0013] FIG. 5 is a front elevation view of a rear portion of the
undercarriage shown in FIG. 1;
[0014] FIG. 6 is a front elevation view of an alternative equalizer
bar for use in the undercarriage shown in FIG. 1;
[0015] FIG. 7 is a magnified front elevation view of the equalizer
bar shown in FIG. 6;
[0016] FIG. 8 is a perspective view of a tracked vehicle with an
undercarriage in accordance with another embodiment of the present
invention;
[0017] FIG. 9 is a rear elevation view of the tracked vehicle shown
in FIG. 8 on uneven terrain;
[0018] FIGS. 10a and 10b are perspective views of the undercarriage
shown in FIG. 8; and
[0019] FIG. 11 is a magnified perspective sectional view of a
portion of the undercarriage shown in FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Reference is made to FIG. 1, which shows an undercarriage 10
for a tracked vehicle 12 in accordance with an embodiment of the
present invention. The tracked vehicle 12 may be any type of
tracked vehicle, such as, for example, a bulldozer, an excavator, a
tractor, a trencher, a pipelayer, a brush tractor and a utility
plow, a tracked trailer.
[0021] The undercarriage 10 permits the tracked vehicle to drive
over uneven terrain, while being configured to require relatively
less maintenance than some undercarriages of the prior art.
Furthermore, the undercarriage 10 is also configured to permit the
tracks of the vehicle 12 (which are shown at 14) to more fully
contact the ground in some instances, as compared to the contact
provided by certain prior art vehicles.
[0022] Referring to FIG. 2a, the undercarriage 10 includes a main
frame 16, which is made up of a frame body 17 and an equalizer bar
18, a first track frame 20 and a second track frame 22 (FIG. 2b).
The frame body 17 may be a solid weldment made up of a plurality of
structural members, which is configured to support the vehicle
body, the cab, the engine and the functional structure (eg. a
drainage plow structure in the exemplary embodiment shown). The
frame body 17 has a front end 24 and a rear end 25, which together
define a longitudinal axis 28 for the undercarriage 10. The frame
body 17 further has a first side 26 and a second side 27. The main
frame 16 itself has a front end 150 and a rear end 151.
[0023] Referring to FIG. 3, the equalizer bar 18 extends laterally
relative to the main frame 16 and has a first lateral end 29 and a
second lateral end 30. The equalizer bar 18 is mounted pivotally to
the front end 24 of the frame body 17 via a pivot joint 32. The
pivot joint 32 may have any suitable structure, such as a
cylindrical tubular member 34a that is rotatable about a
cylindrical core member 34b and permits pivoting of the equalizer
bar 18 about an equalizer bar pivot axis 35, which extends
longitudinally (ie. which extends parallel to or co-linearly with
the longitudinal axis 28).
[0024] Referring to FIG. 2a, the first track frame 20, which is
provided on the first side 26 of the frame body 17, has a front end
36 and a rear end 38.
[0025] At the front end 36 a first front pillow block 40 is
provided, which holds a first front spherical bearing 42 (FIG. 4)
therein. The spherical bearing 42 may be any suitable spherical
bearing, such as one manufactured by FK Bearings of Southington,
Conn. 06489, USA.
[0026] The spherical bearing 42 has a pass-through aperture 44,
through which a laterally extending mounting shaft 46 passes. The
mounting shaft 46 is provided at the first end 29 of the equalizer
bar 18. A retainer plate 48 may be mounted to the outer end of the
mounting shaft 46 to capture the spherical bearing 42 on the shaft
46. It will be noted that the outer race of the spherical bearing
42 is shown to be canted at an angle relative to the vertical in
FIG. 4 to illustrate the type of movement that the bearing 42 is
capable of. However, when the vehicle 12 is travelling over level
ground, the outer race of the bearing 42 will be oriented
vertically.
[0027] Referring to FIG. 2a, at the rear end 38 a first rear pillow
block 50 is provided, which holds a first rear spherical bearing 52
(FIG. 5) therein. The spherical bearing 52 may be similar to the
spherical bearing 42.
[0028] The spherical bearing 52 has a pass-through aperture 54,
through which a laterally extending mounting shaft 56 passes. The
mounting shaft 56 is provided at the rear end 25 (FIG. 2a) of the
frame body 17 on the first side 26. Referring to FIG. 5, a retainer
plate 58 may be mounted to the outer end of the mounting shaft 56
to capture the spherical bearing 52 on the shaft 56.
[0029] Referring to FIG. 2b, the second side 27 of the frame body
17 has a similar arrangement to the first side 26. The second track
frame 22 has a front end 59 and a rear end 60. A second front
pillow block 62 is provided at the front end 59 and holds a second
front spherical bearing 64 (FIG. 4) therein. The second front
spherical bearing 64 may be similar to the first front spherical
bearing 42. The second spherical bearing 64 has a pass-through
aperture 66 through which a laterally extending mounting shaft 68
passes. The mounting shaft 68 is provided on the second end 30 of
the equalizer bar 18. A retainer plate 70 similar to the retainer
plate 48 captures the spherical bearing 64 on the shaft 68. It will
again be noted that the outer race of the spherical bearing 52 is
shown to be canted at an angle relative to the vertical in FIG. 4
to illustrate the type of movement that the bearing 52 is capable
of. When the vehicle 12 is travelling over level ground, the outer
race of the bearing 52 will be oriented vertically.
[0030] Referring to FIG. 2b, at the rear end 60 of the second track
frame 22 a second rear pillow block 72 is provided, which holds a
second rear spherical bearing 74 (FIG. 5) therein. The second rear
spherical bearing 74 may be similar to the first rear spherical
bearing 52.
[0031] The spherical bearing 74 has a pass-through aperture 76,
through which a laterally extending mounting shaft 78 passes. The
mounting shaft 78 is provided at the rear end 25 (FIG. 2b) of the
frame body 17 on the second side 27. Referring to FIG. 5, a
retainer plate 80 may be mounted to the outer end of the mounting
shaft 78 to capture the spherical bearing 52 on the shaft 78.
[0032] By providing horizontally extending mounting shafts the
assembly of the main frame 16, equalizer bar 18 and track frames 20
and 22 can be carried out relatively simply. The mounting shafts 46
and 56 may be connected to the equalizer bar 18 and the equalizer
bar 18 may be connected to the main frame 16. The mounting shafts
68 and 78 may be connected to the rear end 25 of the frame body 17.
The spherical bearings 42, 52, 64 and 74 may be mounted to the
mounting shafts 46, 56, 68 and 78 respectively. The pillow blocks
40, 50, 62 and 72 may be mounted over the spherical bearings 42,
52, 64 and 74 respectively. The assembly including the main frame
16, the equalizer bar 18, the mounting shafts 46, 56, 68 and 78,
the spherical bearings 42, 52, 64 and 74 and the pillow blocks 40,
50, 62 and 72 may be lowered onto the first and second track frames
20 and 22. The positions of the pillow blocks may be adjusted so
that mounting apertures in the pillow blocks may be brought into
alignment with mounting apertures in the track frames 20 and 22, at
which point fasteners, such as bolts (shown for example at 105 in
FIGS. 2a and 2b), may be used to fasten the pillow blocks to the
track frames 20 and 22.
[0033] Referring to FIG. 2a, the spherical bearings 42 and 52 have
centers of rotation shown at 104 and 106 respectively, which define
a first axis of rotation 110 for the first track frame 20.
Referring to FIG. 2a, the spherical bearings 64 and 74 have centers
of rotation shown at 108 and 109 respectively, which define a
second axis of rotation 111 for the second track frame 22.
[0034] Furthermore, referring to FIG. 3, the track frames 20 and 22
have centers of mass shown at 112 and 114 respectively. The lateral
position of the first axis of rotation 110 compared to the lateral
position of the center of mass 112 of the track frame 20 determines
whether gravity causes a moment on the track frame 20 that is
resisted by the ground on which the track frame 20 travels. If
there is a gravity-induced moment on the track frame 20, then the
track 14 (FIG. 1) on the track frame 20 will tend to wear unevenly
across its width and will have reduced traction. Preferably, the
axis of rotation 110 (FIG. 3) is at the same lateral position as
the center of mass 112 of the track frame 20, so that there is no
gravity induced moment on the track frame 20. As a result, when the
vehicle 12 is driving over level ground, the track 14 (FIG. 1) on
the track frame 20 would tend to wear evenly across its width.
Similarly, it is preferable for the axis of rotation 111 (FIG. 3)
to be at the same lateral position as the center of mass 114 of the
track frame 22, so that there is no gravity induced moment on the
track frame 22.
[0035] Referring to FIG. 3, the height of the axis of rotation 110
relative to the center of mass 112 of the track frame 20 also plays
a role in the performance of the undercarriage 10. More
specifically, if the spherical bearings 42, 52, 64 and 74 are
positioned such that the axes of rotation 110 and 111 extend above
or below the centers of mass 112 and 114 respectively, as the track
frames 20 and 22 rotate about the axes 110 and 111, the centers of
mass 112 and 114 will become more and more laterally offset from
the axes of rotation 110 and 111. As a result, moments will be
created on the track frames 20 and 22 as gravity urges the track
frames 20 and 22 towards a stable position of reduced potential
energy. Such moments are detrimental to the performance (eg.
reduced traction) and longevity (eg. non-uniform wear) of the
tracks 14 (FIG. 1).
[0036] For each spherical bearing 42, 52, 64 or 74, there may be
first and second limit members 118 and 120 provided to limit the
amount of rotation that is permitted by the track frames 20 and 22
about the axes of rotation 110 and 111. Limiting the ranges of
rotation of the track frames 20 and 22 inherently imposes
limitations on the topography of the terrain on which the vehicle
12 can drive while keeping its tracks 14 flat to the ground. By
selecting the positions of the limit members 118 and 120 one can
inhibit the vehicle 12 from being driven over terrain that would
impose a risk of tipping the vehicle 12 over. It will be understood
that the selected positions of the limit members 118 and 120 will
be based at least in part on the position of the center of mass of
the vehicle 12. It will be noted that, while a limit member 118 and
a limit member 120 may be provided in association with each
spherical bearing 42, 52, 64 and 74, the limitations on the range
of rotation can be achieved using only one limit member 118 and one
limit member 120 for each track frame 20 and 22.
[0037] The limit member 118 and the limit member 120 may simply be
resilient (eg. rubber) members mounted to the main frame 16 that
are positioned relatively close to selected portions of the track
frames 20 and 22, as shown in FIG. 5.
[0038] The range of movement that is provided about the axes of
rotation 110 and 111 may be any suitable range, such as, for
example, about 15 degrees.
[0039] During operation of the vehicle 12, as the vehicle 12 over
uneven terrain, one of the track frames 20 or 22 may encounter a
patch of ground that is at a different elevation than the patch of
ground encountered by the other track frame 20 or 22, thereby
prompting the equalizer bar 18 to pivot so that the front ends of
the track frames 20 and 22 can accommodate the difference in their
elevations. During pivoting of the equalizer bar 18, the front ends
36 of the track frames 20 and 22 rise and drop relative to the main
frame 16, however, their movement is not strictly vertical; they
instead move in an arc about the pivot axis 35. As a result, the
front ends 36 are laterally offset from the rear ends 38 by some
amount at any given position of the equalizer bar 18 that is off of
horizontal.
[0040] By providing spherical bearings at both the front and rear
ends 36 and 38, the track frames 20 and 22 can pivot as necessary
to accommodate the lateral offset. Furthermore, even when the track
frames 20 and 22 are level the provision of spherical bearings at
both the front and rear ends 36 and 38 of the track frames 20 and
22 is advantageous in that it permits the vehicle 12 (FIG. 1) to
drive on certain kinds of terrain with improved contact between its
tracks 14 and the ground. For example, when driving along a road
that is crowned, the spherical bearings permit the track frames 20
and 22 to angle downwardly so that the tracks 14 are approximately
parallel with their local patch of road. By contrast, some vehicles
of the prior art have connections at the rear ends of the track
frames that substantially only permit pivoting about a lateral
axis. As a result, such vehicles unfortunately do not permit the
track frames to angle downward to accommodate terrain such as a
crowned road. As a result, when such a vehicle drives on a crowned
road (ie. most roads), the laterally inner edges of the tracks
wear, while the laterally outer edges of the tracks do not engage
the road. This can result in premature wear of the tracks,
necessitating their eventual replacement, which is both costly and
time-consuming. Providing the spherical bearings at the front and
rear of the track frames 20 and 22 permits the tracks 14 to engage
the road across relatively more of the width of the track 14,
thereby inhibiting the premature wear that can occur with prior art
vehicles.
[0041] While it has been shown to orient the spherical bearings 42,
52, 64 and 74 such that their pass-through apertures extend
horizontally, it is alternatively possible to configure the
spherical bearings so that their pass-through apertures extend
vertically. An example of such a structure is shown in FIG. 6, in
which an alternatively configured equalizer bar 81 has bearing
mounts 82 and 84 thereon, which hold spherical bearings 86 and 88
therein. As shown in FIG. 7 more clearly, the spherical bearings 86
and 88 have pass-through apertures 90 and 92 respectively, which
are oriented vertically. In this alternative embodiment shown in
FIG. 6, vertically oriented mounting shafts 94 and 96 are provided
at the front ends 97 and 98 of the track frames shown at 99 and
100. The assembly including the main frame 16, the equalizer bar
18, the bearing mounts 82 and 84 and the spherical bearings 86 and
88 may then be lowered onto the vertically oriented mounting shafts
94 and 96 until the bearings 86 and 88 each engage a shoulder on
each of the mounting shafts 94 and 96. Retainer plates 101 and 102
may be fastened to the ends of the shafts 94 and 96 to retain the
bearings 86 and 88 thereon. In this alternative embodiment, the
rear end 25 of the frame body 17 may still be provided with
horizontally oriented shafts 56 and 78 that pass through horizontal
apertures 54 and 76. Alternatively, it is possible that at the rear
end 25, bearing mounts may be provided that are similar to the ones
proposed on the equalizer bar 81 and that hold spherical bearings
with pass-through apertures that are oriented vertically, and which
mount on vertically oriented mounting shafts mounted at the rear
ends of the track frames 99 and 100.
[0042] While it has been shown to provide the undercarriage 10 with
an equalizer bar 16, it is optionally possible to provide the
undercarriage 10 without an equalizer bar 16. In such a case, the
spherical bearings 42 and 52 connect the fronts of the track frames
20 and 22 to the main frame, which would be a fixed weldment.
[0043] Reference is made to FIG. 8, which shows an undercarriage
200 for use in the tracked vehicle 12 instead of the undercarriage
10, in accordance with another embodiment of the present invention.
The undercarriage 200 may be similar to the undercarriage 10, but
with two modifications. One modification is that the main frame of
the undercarriage 200 is shown at 202 and includes a frame body
204, a front equalizer bar 206 and a rear equalizer bar 208. The
frame body 204 is similar to the frame body 17 (FIG. 1), except
that it is configured for the mounting of two equalizer bars
instead of one. The front and rear equalizer bars 206 and 208 may
each be similar to the equalizer bar 18 shown in FIG. 3. The front
equalizer bar 206 is mounted about a front equalizer bar pivot axis
210 which extends longitudinally (ie. which extends parallel to or
co-linearly with the longitudinal axis of the main frame). The rear
equalizer bar 208 is mounted about a rear equalizer bar pivot axis
212 which extends longitudinally (ie. which extends parallel to or
co-linearly with the longitudinal axis of the main frame).
[0044] By providing the front and rear equalizer bars 206 and 208
for the main frame 202, the main frame 202 has significantly
increased flexibility in terms of the types of terrain that can be
handled. As an example, the main frame 202 can hold the cab (shown
at 214 in FIG. 9) upright while driving on terrain shown at 215
that is sloped downwards laterally. One or more hydraulic or
pneumatic cylinders (not shown) can be provided between the frame
body 204 and one or both equalizer bars 206 and 208 to control the
angle of one or both equalizer bars 206 and 208 relative to the
frame body 204. In a preferred embodiment, cylinders would be
mounted between the frame and the rear stabilizer bar 208 on both
sides of the pivot axis 212, and would be controlled by a hydraulic
leveling system.
[0045] Another modification to the undercarriage 200 relative to
the undercarriage 10 (FIG. 1) is that the undercarriage 200
incorporates a different type of spherical bearing. The spherical
bearings in the undercarriage 200 are shown at 218, 220, 222 and
224 respectively in FIGS. 10a and 10b. The spherical bearings 218,
220, 222 and 224 may all be substantially identical, and may
include a ball trunnion 226 (FIG. 11) and a ball trunnion support
member 228.
[0046] In a preferred embodiment, the ball trunnion 226 is a cast
steel member, and the ball trunnion support member 228 is also a
cast steel member. As a result, it was found that surprisingly, the
spherical bearings 218, 220, 222 and 224 do not require any
lubrication. The bearings 218, 220, 222 and 214 are able to pivot
as necessary during operation of the tracked vehicle 12 without the
need for grease or oil to be present between the sliding surfaces
shown at 230 and 232 of the ball trunnion 226 and the ball trunnion
support member 228 respectively. By eliminating the need to
lubricate the surfaces 230 and 232, a maintenance task on the
vehicle 12 is eliminated, thereby saving time and cost.
[0047] The ball trunnion support members 228 may be in the form of
pillow blocks as shown in FIGS. 10a and 10b, and may be split into
upper and lower portions 234 and 236 for the introduction or
removal of the ball trunnion 226 therefrom. It will be noted that
the upper portions 234 of the ball trunnion support members 228 are
not shown in FIGS. 10a and 10b, so as to permit illustration of the
upper portions of the ball trunnions 226.
[0048] While the above description constitutes a plurality of
embodiments of the present invention, it will be appreciated that
the present invention is susceptible to further modification and
change without departing from the fair meaning of the accompanying
claims.
* * * * *