Note: Descriptions are shown in the official language in which they were submitted.
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WHEELED WORK MACHINE
BACKGROUND OF THE INVENTION
The present invention relates to power
machinery. More particularly, the present invention
relates to an overall configuration or layout of a
wheeled work machine.
Although compact tractors, skid steer
loaders and other types of wheeled work machines have
enjoyed great success and are used throughout the
world in a number of different applications, these
machines are not well suited for all work
environments. For example, compact tractors, while
useful in some applications, frequently have a number
of characteristics, which limit their usefulness in
some applications. Typically, compact tractors have
poor visibility to the front (i.e., toward the
bucket). Compact tractors also typically have
limited hydraulic systems for operation of
attachments, and the attachments are frequently
behind the operator, forcing the operator to turn
around to see them. Further, for the operator of the
compact tractor, entry/egress is often awkward or
difficult and usually the tractor only provides
seating for a single person. Also, compact tractors
lack a cargo area, which severely limits their
usefulness in many applications. Other common
limitations of compact tractors include a relative
lack of stability and the rough ride provided by many
compact tractor designs.
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Utility carts. are another type of wheeled
work machine, which have a number of characteristics
that limit their usefulness in some applications.
For example, utility carts do not have a loader
option, and typically have limited or no attachment
capability. Also, utility carts generally have
limited, if any, onboard hydraulic systems for the
operation of hydraulic attachments. Other typical
characteristics of utility carts, which limit the
applications in which they can be used, include a
relatively large turning diameter and a limited
ability to carry cargo. Utility carts are frequently
low on power needed to pull equipment or carry cargo.
In many applications, a small turning
diameter would be a beneficial feature of a wheeled
work machine. However, many wheeled work machines,
if not most, do not have small turning diameters.
Thus, to change direction of travel, these machines
need to stop, change direction, reorient the machine,
and proceed in the intended direction. Typically,
machines with front steerable wheels (for example,
tractors and most utility vehicles) have to maintain
a short wheelbase in order to maintain a small
turning diameter, as wheelbase and turning diameter
are inversely proportional. However, a short
wheelbase has a negative effect by decreasing
stability, lift capacity, operat~r area, cargo area,.
etc.
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Most compact tractors maintain a relatively
small turning diameter by turning the front wheels
extremely sharply and generally by having a shorter
wheelbase. Turning the wheels excessively sharp can
be damaging to sensitive grounds such as lawns and
turf areas. Further, even with a short wheelbase
(and the disadvantages which result), the relatively
small turning diameter of compact tractors may not be
small enough for some applications. Most utility
parts have a large turning diameter, which is
unacceptable for many applications, due to the fact
that they cannot turn the wheels as sharply as a
typical tractor and that they require a longer
wheelbase to place the operator seating, engine,
cargo area, etc. A wheeled work machine which
provides a small turning diameter without the
disadvantages associated with the short wheelbase of
tractors, would be a significant improvement in
wheeled work machine applications.
Generally, wheeled work; machines such as
compact tractors, utility carts, and other types have
numerous limitations, which prevent them from being
suited for some applications. Some of these
limitations are discussed above with reference to
compact tractors and utility vehicles, but they may
apply to other types of work machines as well. In
addition to turning diameter characteristics, a
common limitation in many wheeled work machines is a
general inability to carry more than one person to a
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work site. Other limitations include an inability to
carry cargo, poor visibility, lack of attachments
such as a bucket or loader, low power, and
instability, to name a few.
Skid steer loaders have proven to be highly
useful in many applications. Skid steer loaders have
features, which are often highly beneficial for
certain work environments. For example, skid steer
loaders can support a wide variety of work tools and
attachments. Skid steer loaders can also be turned
very sharply. Numerous other features of skid steer
loaders provide these machines with highly
advantageous capabilities. '
Although skid steer loaders have enjoyed
great success and are used throughout the world in a
number of different applications, the skid steer
loader is not well suited for all work environments.
There is thus a continuing need for an
improved wheeled work machine. A machine that
addresses one, several or all of the deficiencies
discussed above would be particularly advantageous.
SUMMARY OF THE INVENTION
A wheeled work machine of a first aspect of
the present invention includes a rigid frame assembly
having a support with a boom pivot. A front wheel
assembly is joined to the frame assembly proximate
the support, while a rear wheel assembly is joined to
the frame assembly at an end remote from the support.
The frame assembly further supports an engine,
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operator platform and cargo support. The operator
platform is disposed between the boom pivot and the
engine, while the cargo support is disposed behind
the operator platform.
A second aspect of the present invention is
a rigid frame assembly for a wheeled work machine that
includes a pair of spaced apart longitudinal members
with transverse ties. The longitudinal members define
a cargo support portion at one end of the
longitudinal members and a front portion at an end
remote from the cargo support portion. A cab portion
is disposed between the cargo support portion and the
front portion. The cargo support portion has a
transverse width greater than at least one of the
cargo support portion and the front portion. An
upstanding support is joined to the front portion. The
support includes a lift arm pivot.
A wheeled work machine in accordance with a
third aspect of the present invention includes a rigid
frame assembly and front and rear wheel assemblies
joined to the frame assembly. An engine is mounted to
the frame assembly and an operator seat is supported by
the frame assembly at least partially between the front
wheel assembly and the engine. A cargo support is
supported by the frame assembly behind the operator
seat and over at least a portion of the engine. A
radiator assembly is supported by the frame at least
partially behind the operator seat for cooling the
engine. The radiator assembly includes a radiator
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oriented in a generally flat position relative to the
ground to facilitate a compact design of the wheeled
work machine. .
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a wheeled
work machine pf the present invention.
Fig. 2 is a side elevational view of the
wheeled work machine with portions removed.
Fig. 3 is a perspective view of the wheeled
work machine with portions removed.
Fig. 4 is a side elevational view of the
wheeled work machine with portions shown with dashed
lines.
Fig. 5 is a bottom plan view of the wheeled
work machine.
Fig. 6 is a side elevational view of a lift
arm assembly.
Fig. 7 is a rear elevational view of the
lift arm assembly.
Fig. ~ is a front elevational view of the
lift arm assembly.
Fig. 9 is a perspective view of a frame
assembly.
Fig. 10 is a bottom plan view of a frame
assembly.
Fig. 11 is a side elevational view of a
front suspension.
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Fig. 12 is a top plan view of the front
suspension.
Fig. 13 is a front elevational view of the
. front suspension.
Fig. 14 is a side elevation view of a rear
portion of the frame assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
An exemplary embodiment of a wheeled work
machine 10 of the present invention is illustrated in
Figs. l, 2 and 3. The wheeled work machine 10
includes a rigid frame assembly 12 having a support
14 with a boom pivot 16. A front wheel assembly 18 is
joined to the frame assembly 12 proximate the support
14. Similarly, a rear wheel assembly 20 is joined to
the frame assembly 12 at an end thereof remote from
the support 14.
The wheeled work machine 10 further
includes an engine 24, an operator platform 26
(herein embodied as a seat) and a cargo support 28.
location of these elements in combination
with the support 14 for the boom pivot 16 provides a
unique, multi-purpose machine that is compact and
usable in a number of different applications. In
particular, the operator platform 26 is located
behind the support 14 and between the boom~pivot 16
and the engine 24. In addition, the cargo support 28,
which is also supported by the frame assembly 12, is
located behind the operator platform 26 and, in one
embodiment, over at least a portion of the engine 24.
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In the embodiment illustrated, the engine 24 is
coupled to a ,hydraulic pump 30, which in turn, is
coupled to a lift cylinder 32. Under selective
control by the operator, the lift cylinder 32 can be
used to tilt a lift arm 34 that is pivotally coupled
at the boom pivot 16. In a manner discussed below,
various tools can be attached to the lift arm 34 to
perform various work functions at a position
convenient for forward viewing by the operator
sitting in operator platform 26. For instance, as
illustrated, a bucket 36 can be coupled to a remote
end 49 of the lift arm 34 and used to scoop or lift
various types of materials. As illustrated and
discussed below, a tilt cylinder 38 can also be
coupled between the lift arm 34 and the bucket 36,
which allows the bucket 36 to be pivoted relative to
the lift arm 34. It should be noted however that the
bucket 36 is but one exemplary tool that can be used
with the wheeled work machine 10. However, as another
aspect of the present invention, the wheeled work
machine 10 includes a single lift arm or boom 34
pivotally joined to the boom pivot 16. Use of a
single lift arm 34 provides a stable, strong lifting
device, but also minimizes obstruction to the remote
end of the lift arm 34 as viewed by the operator
sitting in operator platform 26. Nevertheless,
although illustrated as a single lift arm 34, those
skilled in the art can appreciate that additional
lift arms can be used, for instance, in a side-by-
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side relationship from the support or supports 14
disposed in front of the operator platform 26, and
therefore, this configuration is also considered
another embodiment of this aspect of the present
invention.
As illustrated, the lift arm 34 extends
between a line between wheels of the front wheel
assembly 18. In one embodiment, a minimum angle 39
formed between the boom pivot 16 and a second boom
pivot 42 typically provided at a remote end of the
lift arm 34 and a normal reference line 44 from the
boom pivot 16 to a level ground surface is in the
range of 20 to 35 degrees and in a further embodiment
in the range of 22-28 degrees.
Using a rigid lift arm 34 between pivots 16
and 42 enables the bucket 36 to move forwardly during
lifting from the initial angle 39 described above.
The forward movement of~the bucket 36 allows a less-
experienced operator to easily fill the bucket 36
without requiring the wheeled work machine 10 to move
forward during lifting. Due to the path taken by the
bucket 36, the bucket 36 is filled during,
approximately, the first 65 degrees of travel.
Although many forms of loaders have the capability to
raise a loaded bucket, many do not have the required
traction or power to push the bucket completely into
a pile of heavy material. Likewise, because many
buckets lift primarily vertically, due to the long
extension of the booms or lifting arms, many machines
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do not have the ability to lift a full bucket through
the material that is above the bucket in view that
that bucket was driven into the pile. In contrast,
the large forward component of bucket movement during
lifting enables the bucket 36 to be easily filled
with rotation of the lift arm 34. In one embodiment,
the lift arm 34 pivots through an arc of 102 degrees
from its initial starting position. In this manner,
once the bucket 36 is filled, the bucket 36 moves
away from the pile of material. The use of a single
boom support 14 and a single lift arm 34 is
particularly beneficial because this construction
enables a compact assembly of 'the work machine 10 and
also provides excellent viewing of the remote end of
the lift arm 34 for the operator sitting in the
operator platform 26.
In a preferred embodiment, the height of
the pivot 16 with respect to a level ground surface
is in the range of 48 to 54 inches, for example,
50.94 when angle 39 is 27.5°. Other dimensions
include the position of pivot 42 with respect to
pivot 16 (55 to 49 inches, preferably 51.83 when
angle 39 is 27.5°) and the height of pivot 42 above
the ground (2 to 8 inches, preferably 5 inches when
angle 39 is 27.5°). Similarly, the position of pivot
48 with respect to pivot 16 is in the range of 42.5
to 48.5 inches, preferably 45.5 when angle 39 is
27.5°, and the height of pivot 48 above the ground is
in the range of 9 to 15 inches, preferably 12 when
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angle 39 is 27.5°. Likewise the position of the lift
cylinder connection (pivot 47) to lift arm 34 with
respect to pivot 16 is 13 to 19 inches, preferably 16
when angle 39 is 27 . 5 ° , while the length of the lift
arm 34 (from pivot 16 to pivot 42) is also 49 to 55
inches, preferably 51.83 when angle 39 is 27.5°.
As discussed above, the lift cylinder 32 is
operably coupled between the frame 12 and the lift
arm 34 to pivot the lift arm 34. In a further
embodiment, the remote end 49 (Fig. 6) of the lift
arm is joined, for example, pivotally, to the frame
assembly 12 between the wheel assemblies 18 and 20 to
provide a compact assembly. In this manner, the front
wheel assembly 18 is disposed between the lift arm 34
and the lift cylinder 32. Use of a single lift
cylinder 32 in the center of the wheeled work machine
also minimizes any damage thereto.
In the embodiment illustrated, a quick
attachment interface member or assembly 50 is
provided at the remote end of the lift arm 34 forward
of the operator platform 26, which is a far more
convenient position of the tool at the end of the
lift arm 34. The quick attachment interface 50 has
been utilized extensively by Bobcat Company and sold
under the trade name BOBTACH. The interface assembly
50 allows quick attachment of various work tools such
as buckets, grapples, brooms, augers or the like. In
this manner, by including the interface 50, the work
machine 10 can readily accept and use all of the
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various types of work tools currently in use or
developed in the future.
Referring to Figs. 6, 7 and 8, the
interface 50 includes an attachment plate 52
pivotally attached to the second pivot 42. The
tilting of the attachment plate 52 is controlled by
the tilt cylinder 38, which is operably coupled
between the lift arm 34 and the attachment plate 52.
In the embodiment illustrated, a bracket 56 is
provided with a pivot 58 to which an end of the tilt
cylinder 38 is coupled. A second end 54 of the tilt
cylinder 38 is operably coupled to the interface 50,
and in the embodiment illustrated, through a link 60
that is pivotally coupled to the attachment plate 52.
A standoff support 64 is also pivotally coupled to
the lift arm 34 and to a common pivotal connection
between the tilt cylinder 38 and the link 60.
Typically, the attachment plate 52 includes
a lip 70 that will fit under a flange on an
attachment or work tool such as the bucket 36. As is
well known, apertures provided on the work tool will
align with apertures of the attachment plate 52, or
at least sliding wedges 74 provided on the attachment
plate 52. The wedges 74 move linearly on the
attachment plate 52. Typically, each of the wedges 74
have a tapered wedge end to aid in pushing the wedge
into the desired aperture on the attachment plate 52
or work tool when it is in position to be mounted. A
spring 78 joins each of the wedges 74 to a
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corresponding lever 80 that is pivotally connected to
the attachment plate 52. The arrangement is
conventional and the levers 80 and spring 78 will
load each corresponding wedge 74 downward to lock the
wedge 74 as well as upward in an unlocked position.
An actuator end of each of the levers 80 carry pivot
pins 77 for the springs 78. Handles are provided on
each of the levers 80 in order to allow manual
operation. A power actuator such as disclosed in U.S.
Patent 5,562,397 can also be provided, if desired.
Some work tools or attachments couplable to
the interface 50 can be powered or operated
hydraulically. The work machine 10 can include
hydraulic couplings that are fluidly coupled to the
pump 30 through suitable control valves or the like.
The couplings can be provided at or near the
interface 50 and/or proximate the support 14,~for
example, on the work machine body at 81 (Fig. 1).
Likewise, if desired, hydraulic couplings can be
provided at the rear of the work machine proximate
the cargo support 28.
Referring to Figs . 3 and 5, movement of the
work machine 10 is provided by wheels 94 mounted on
each of the wheel assemblies 18 and 20. Either or
both of the wheel assemblies 18 and 20 can be powered
by the engine 24, for example, by mechanical drive
shafts, chains, belts or the like. In the embodiment
illustrated, hydraulic drive motors are mounted to
the housing assemblies 84, which in turn, drive the
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wheels 94. The drive housing assemblies 84 can be
independent, i.e., one for any chosen wheel 94, or as
illustrated, have opposed output shafts 88 to drive a
pair of wheels 94.
The drive housing assemblies 84 can include
gear reduction, wet disk brake, differential,
differential lock and the output shafts 88. In one
embodiment as illustrated, pivotal couplings 90 are
provided at the ends of the drive housing assemblies
84 and are coupled to hub assemblies of the wheels 94
to allow the associated wheels 94 to pivot. Tie rods
94 coupled to a suitable steering mechanism having a
steering wheel 98 (Fig. 1) proximate the operator
platform 26 can control pivotal motion of the wheels
94. In the embodiment illustrated, each of the wheel
assemblies 18 and 20 allow the corresponding wheels
94 to be pivoted providing for all-wheel steering
capability resulting in a small turning diameter.
Nevertheless, in an alternative embodiment, the
steering mechanism can be coupled. to only the front
wheel assembly 18, or to only the rear assembly 20.
The steering mechanism for the front and/or
rear wheels 94 can take any number of forms such as a
mechanical linkage between the steering wheel 98 and
the steerable wheels of the front wheel assembly 18
and/or rear wheel assembly 20. In the embodiment
illustrated, the wheels are steered using hydraulic
cylinders mounted to the drive housings. There can be
a steering cylinder for each steerable wheel, or
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pairs of wheels can be steered with a single cylinder
and a tie rod connection. The steering wheel 98 can
be coupled to a steering sector to direct pressurized
hydraulic fluid to the appropriate steering cylinders
thus obtaining steering of the desired wheels. The
steering modes can illustratively include front wheel
steer, rear wheel steer, coordinated steer (in which
the front and rear wheels are steered in pairs in
opposite directions to implement tighter turns) and
crab steer (in which the front rear wheels are again
steered in pairs but in the same direction). A
control valve can be further used in the hydraulic
circuit of the rear wheels,' wherein the control valve
receives an input related to the type of steering
desired for the rear wheels, e.g. coordinated or crab
steer, and properly directs pressurized to the
steering actuator based on the desired mode of
steering. Allowing the work machine 10 to steer all
of the wheels 94 significantly minimizes damage to
the ground surface, which can occur during travel to
the work site or operation of the work machine 10 at
the job site.
In one embodiment, multiple seat positions
can be provided through individual seats, as
illustrated, or a common bench seat. Configured in
this manner, the work machine 10 allows side-by-side
seating positions for the transportation of -two or
more individuals to the job site. It should be
further noted that the operator platform 26 is
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disposed on the frame assembly 12 between the wheel
assemblies 18 and 20 so as to provide a stable
platform. In the embodiment illustrated, the operator
platform 26 forms part of an operator station 100
that can include a canopy 102. A windshield 104, back
window 106 and doors (not shown) can also be provided
in order to enclose the operator station 100, if
desired.
An instrument cluster and dash 110 is
generally disposed in front of the operator platform
26 and behind the boom pivot 16 and includes gauges,
controls and the like for operation of the work
machine~l0. The instrument cluster and dash 110 is
also disposed at a level such that an upper surface
thereof allows an operator of height in the range of
a female in the fifth percentile to a male in the
ninety-fifth percentile to view an end of the lift
arm 34 remote from the boom pivot 16.
The cargo support 28 located behind the
operator platform 26 and supported by the frame
assembly 12 allows the transportation of tools and/or
other material to the job site. Although exemplified
herein as a cargo box (open or enclosed), which can
also tilt through a suitable lift cylinder and hinge
coupling the cargo box to the frame assembly 12,
which has a floor 120 and side walls 122 (with or
without tailgates or side gates), the cargo support
28 can include other forms of containers or
platforms. For instance, the cargo support can also
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include a sprayer having a suitable tank for
containing liquid, a hopper such as for spreading
sand, or a plurality of tool boxes to name a few.
Referring Figs. 2 and 5, engine 24 is
generally located behind operator platform 26 and
below cargo support 28. In one embodiment, a
transverse engine is supported by the frame assembly
12 at this location. The transverse engine 24
includes a crank shaft indicated by dashed line 138
oriented transversely with respect to a longitudinal
axis (front to back) of the work machine 10. Although
other orientations of engine 24 can be used, the
transverse engine provides a compact assembly that
can also be easily serviced.
Also shown in Figs. 2, 4, 5 and 14 is a
radiator assembly 145 for cooling engine 24.
Radiator assembly 145 is supported at least partially
beneath cargo support 28 by longitudinal frame
members 130. In one embodiment, longitudinal frame
members 130 are C-channel frame members (see for
example FIG. 9). In these embodiments, radiator
assembly 145 can be supported via positioning
between, and within the C-channels of, frame members
130.
In the embodiment illustrated, radiator
assembly 145 is supported by longitudinal frame
members 130 behind the rear axle. This is shown in
the Figs. by placement of the radiator assembly
behind rear wheel 94 or suspension assembly 180.
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Radiator assembly 145 includes a radiator
151 and optionally one or more air flow generation
device 153 such as a fan or other blower for removing
heat energy by moving air past radiator 151. In the
illustrated embodiments, radiator assembly 145
includes dual fans or air flow generation devices
153, with one positioned on top of radiator 151, and
one positioned below radiator 151. In other
embodiments, radiator assembly 145 and air flow
generation devices 153 can be positioned elsewhere.
Radiator assembly 145 also includes hoses 146 which
carry coolant between engine 24 and radiator 151.
Also, radiator assembly can include other features,
for example an airflow redirecting structure or
mechanism which redirects airflow from fans 153
toward the rear of the wheeled work machine in order
to minimize dust in the area of operator station 100.
Radiator 151 is supported relative to
longitudinal frame members 130 and the ground in a
"flat" position in order to further facilitate the
compact design of wheeled work machine 10. In other
words, radiator 145 has a vertical dimension relative
to the ground which is less than its longitudinal
dimensions indicated generally at 147 and 148 in
Figs. 2, 4, 5 and 14. Generally, radiator 151 is
oriented with its longitudinal dimensions
substantially parallel to the ground to give it a low
profile. However, radiator 151 can also be oriented
at slight angles relative to the ground, for example
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up to about 45° or less to create the exhaust.
Including a flat radiator 151 for cooling of engine
24 allows the radiator to be supported by
longitudinal frame members 130 beneath cargo support
28. In addition to saving space and facilitating a
compact and stable wheeled work machine
configuration, utilization of a flat radiator
assembly 145 placed in this position can also serve
to protect the radiator from damage relative to other
potential locations on the wheeled work machine.
Referring now to Figs. 5, 9 and 10, the
frame assembly 12 is a "rigid" frame assembly wherein
' no frame articulation is provided between the front
wheel assembly 18 and the rear assembly 20. In the
embodiment illustrated, the frame assembly 12
includes longitudinal frame members 130 extending
from the rear wheel assembly 20 toward the front
wheel assembly 18. Generally the frame assembly 12
includes a cargo support portion 132, a middle
portion 134 and a front or boom support portion 136.
The portions 132, 134, 136 can be attached together
as illustrated in FIG. 9 wherein cargo support
portion 132 and middle portion 134 are generally
attached and defined at connection 135, wherein
longitudinal members 130 extend from front to back
and are defined by longitudinal sections forming
portions 132, 134 and 136. Alternatively, portions
132, 134, 136 may be integral. The cargo support
portion 132 and the boom support portion 136 are not
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as wide as the middle portion 134. The narrower width
of the cargo support portion 132 and the front or
boom support portion 136 allows for increased
pivoting of the wheels 94 for steering of either the
front wheel assembly 18 and/or the rear wheel
assembly 20. In contrast, the wider transverse width
of the middle portion 134 allows accommodation of the
transverse oriented engine 24 and provides a stable
mount for the operator station 100.
In the embodiment illustrated, the front or
boom support portion 136 is particularly strengthened
so as to inhibit bending or twisting due to loads
carried by the lift arm 34 such as with bucket 36.
The front or boom support portion 136 can therefore
include a plurality of transverse members
139extending between the longitudinal members 130, or
as illustrated herein, one or more plate members 140
to which the lift cylinder 32 is pivotally connected.
An elongated aperture 142 can be provided in an upper
plate member 140 as illustrated. in Fig. 9 to
accommodate pivoting motion of the lift cylinder 32
during operation thereof. Additional support and
resistance against twist to the frame assembly 12 can
result from a torque tube 143 being provided at or
near the connection 135 of middle portion 134 and
cargo support portion 132.. As described below,
transverse members 177, 179 provide support for rear
suspension assembly 20.
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The support 14 is joined to ends of the
longitudinal 130 members and to the transverse ties
or the plate members 140 as illustrated in Figs. 9
and 10. Generally, the support 14 includes side
plates 150, an upper back plate 152 and a lower front
plate 154, both of which connect the side plates 150
together. An inclined connecting plate 155 can also
be provided with an aperture 156 to allow the lift
cylinder 34 to extend therethrough. Extending
supports 158 can also be provided for support of the
operation station 100 on elastomeric isolators, if
desired. The operator station 100 can be supported on
two additional elastomeric isolators at the rear, 'if
desired. In this manner, the operator station 100
increases the strength of the boom support 14. It
should be noted that although direct support for the
operator station 100 is provided at supports 158 and
at the rear of the fxame 20, the operator platform 26
is nevertheless supported by the frame and disposed
between the boom support 14 and the cargo support 28.
It should be understood that the location of the
mounts for operator station 100 and thus the operator
platform 26 can occur anywhere on the frame 20.
Referring to Fig. 2, the longitudinal frame
members 130 can extend below the operator station
100, and in particular, at a level below an upper
surface 160 of the floor panel of the operator
station 100 in order to allow easy entry and egress
from the operator station 100. As further
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illustrated, each of the longitudinal frame members
130 can extend upwardly through the middle portion
134 and then over the rear drive assembly 20. In this
manner, the operator station 100 and operator
platform 26 can be lower so as to allow easy entry
into and egress from the operator station 100 and
provide a stable platform. Similarly, the front or
boom support portion 136 extends at substantially the
same level as the portion of the longitudinal frame
members 130 below the upper surface 160 of the floor
panel. As illustrated, the thickness of the
longitudinal frame' members 130 for the inclined
portions of the middle portion 134 is greater than
the thickness of the longitudinal members 130 in the
cargo support portion 132 and front or boom support
portion 136 so as to concentrate section modulus
where needed in order to inhibit bending associating
with heavy loads on the remote end of the lift arm.
34. Alternatively, front portion 136 and middle
portion 134 can be of increased height to concentrate
section modulus where needed. Likewise, the height of
the longitudinal frame members 130 in the cargo
support portion 132 can be similar to the front
portion 136 with only the inclined portions of middle
portion 134 being of greater height. Although the
frame assembly 12 has unique physical characteristics
for the reasons discussed above, these physical
characteristics can be included in numerous aesthetic
designs.
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In spite of the rigid frame assembly 12
described above, which is well suited for handling
loading due to the lift arm 34, each of the wheel
assemblies 18 and 20 can further include suspension
assemblies allowing the smooth transportation of
workers and materials to the job site. Referring to
Figs. 4 and''14, an exemplary suspension assembly 180
for the rear wheel assembly 20 can include a leaf
spring or springs 182 connected at remote ends
thereof to each of the longitudinal frame members
130. Opposed ends of the rear wheel assembly 20 are
joined to a center portion of the leaf spring or
springs 182. Zeaf spring 182 is supported by members
177, 179 attached to the frame assembly 12. In the
embodiment illustrated in Figs. 9 and 14, member 177
is a transverse bracket extending across the cargo
support portion 132, while member 179 is a bracket
mounted to torque tube 143. Other suitable suspension
elements that can be used include coiled springs, and
the like, operably coupled between the rear wheel
assembly 20 and the frame members 130.
If further desired, an overtravel assembly
184 can be provided and operable when substantial
loads are carried by the work machine 10, for
example, on the cargo support 28 when full deflection
of the leaf spring or springs 182 is obtained. The
overtravel assembly 184 can have a second spring rate
stiffer than that of the leaf spring or springs 182
and can be operable only when a selected amount of
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deflection has been obtained. For instance, the
second spring assembly 184 can comprise compressive,
elastomeric stops that selectively engage portions of
the rear drive assembly 20.
Schematically illustrated in Fig. 4, a
suspension assembly 190 for each side of the front
assembly 18 can include fluidic dampers 192 joined
between the front wheel assembly 18 and the frame
assembly 12. Coiled springs can also be provided. The
fluidic damper 192 can include fluid chambers formed
on opposite sides of a center piston in a suitable
cylinder housing 196. Generally, the center piston or
piston rod 194 is coupled to one of the front wheel
assembly 18 or frame assembly 12, while the cylinder
housing 196 is coupled to the other. During
transportation to the job site, control valves such
as check valves and/or pilot valves can be operated
so as to allow fluid flow between the opposed fluidic
chambers, wherein the fluid flow is restricted so as
to provide damping. However, when it is desired to
perform work using the lift arm 34, for example by
picking up material with the bucket 36, the control
values for each of the suspension assemblies 198 for
the front wheels 94 can be operated so as to
substantially inhibit or prevent fluid flow in order
to substantially hold the center piston. in a
substantially fixed position relative to the cylinder
housing 196. In this manner, the suspension
assemblies 190 are "locked" in order to prevent, or
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at least substantially inhibit, relative motion
between the front wheel assembly 18 and the frame
assembly 12. If desired, similar lockable suspension
assemblies can also be provided between the frame
assembly 12 and the rear wheel assembly 20.
Figs. 11,. 12 and 13 illustrate a front
suspension assembly 198. The front suspension
assembly 198 includes on each side of the frame 20 an
upper link 200 and a lower link 201 that are used to
control the location of the corresponding drive shaft
or axle 88 relative to the frame 20. Pivot mounts 210
are provided on the frame 20 and on axle supports 215
at 211 for each of links 200. These pivots are
parallel to each other and perpendicular to the
longitudinal axis of the frame 20. Pivot mounts 213
are provided on the frame 20 and on the supports 215
for each of links 201. Supports 215 are connected to
ends of the drive housing assemblies 84. An oblique
angle 218 formed between lower link 201 and the
longitudinal axis of the vehicle is set to provide
lateral stability to the driving house 84 and still
offer a defined range ~of motion for the axle. For
example, the angle 218 can be 45 degrees. The
geometry of the links 200 and 201 controls rotation
of axles throughout its vertical movement due to
input into the suspension system 198. Coils 219 over
shocks 220 or the fluidic dampers 192 mount to the
drive housing 84 and pivot connections are provided
on the boom support 14. The coils 219 allow the
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suspension to respond to input loads to the work
machine either through the wheels 94 or the loader
arm 34 or a combination of the two. It should be
noted a torsion spring can be provided at each of the
pivots 210 in the alternative or in addition to the
coils 219.
The arrangement of the links 200 and 201
maintains the front wheel assembly 18 position under
the front of the machine by working to inhibit any
fore-to-aft or side-to-side movement. The geometry of
the links 200 and 201 allows primarily rotational
motion of the front wheel assembly 18 and provides for
suspension travel.
Although the present invention has been
described with reference to preferred embodiments,
workers skilled in the art will recognize that
changes may be made in form and detail without
departing from the spirit and scope of the invention.
