U.S. patent application number 10/574270 was filed with the patent office on 2007-06-28 for articulated dump truck.
This patent application is currently assigned to Technology Investments Limited. Invention is credited to Eanna Pronsias Timoney, Sean Timoney.
Application Number | 20070145809 10/574270 |
Document ID | / |
Family ID | 34395491 |
Filed Date | 2007-06-28 |
United States Patent
Application |
20070145809 |
Kind Code |
A1 |
Timoney; Eanna Pronsias ; et
al. |
June 28, 2007 |
Articulated dump truck
Abstract
An article dump truck has a front tractor unit connected to an
associated rear trailer unit with a tipping container by an
articulated coupling. The articulated coupling is operable to allow
the front tractor unit and rear trailer unit to pivot about a
vertical pivot axis, rams being provided to turn the front tractor
unit and rear trailer unit about the pivot to steer the dump truck.
The articulated coupling also allows the front tracter unit and
rear trailer unit to rotate relative to each other about a
longitudinal axis of the dump truck. In addition, the front tractor
unit has a front chassis mounted on a pair of wheels by an
independent suspension system.
Inventors: |
Timoney; Eanna Pronsias;
(Navan, IE) ; Timoney; Sean; (Dublin, IE) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Technology Investments
Limited
Navan
IE
|
Family ID: |
34395491 |
Appl. No.: |
10/574270 |
Filed: |
October 1, 2004 |
PCT Filed: |
October 1, 2004 |
PCT NO: |
PCT/IE04/00136 |
371 Date: |
January 22, 2007 |
Current U.S.
Class: |
298/22P ;
180/235 |
Current CPC
Class: |
B62D 53/021 20130101;
B60G 2200/422 20130101; B60G 2204/124 20130101; B60G 2204/1244
20130101; B60G 2206/60 20130101; B60G 2204/19 20130101; B60G
2300/026 20130101; B62D 12/00 20130101; B60G 2204/143 20130101;
B60G 3/20 20130101; B60G 11/16 20130101; B60G 2204/15 20130101;
B60G 2206/124 20130101; B60G 2300/07 20130101; B60G 2202/12
20130101; B60G 2206/0114 20130101; B60G 2200/144 20130101; B60G
7/02 20130101 |
Class at
Publication: |
298/022.00P ;
180/235 |
International
Class: |
B60P 1/16 20060101
B60P001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2003 |
IE |
S2003/0720 |
Oct 1, 2003 |
IE |
S2003/0721 |
Claims
1-47. (canceled)
48. An articulated dump truck vehicle, including: a front tractor
part connected to an associated rear trailer part by means of an
articulated coupling which is mounted between a rear end of the
tractor part and a front end of the trailer part, said articulated
coupling being operable to allow the front tractor part and the
rear trailer part to rotate relative to each other about a first
vertical axis, with steering means for turning the front tractor
part relative to the rear trailer part about said first vertical
axis for steering the vehicle, and said articulated coupling also
allowing the front tractor part and the rear trailer part to rotate
relative to each other about a second longitudinal axis of the
vehicle, the front tractor part having a front chassis, a pair of
front wheels being mounted by a front suspension assembly on the
front chassis, a prime mover mounted on said front tractor part and
driveably connected to at least one pair of wheels on the vehicle,
a vehicle driving station on said front tractor part with controls
for vehicle drive and steering, the rear trailer part having a rear
chassis, at least two pairs of rear wheels mounted by a rear
suspension assembly on the rear chassis, a tipping container
pivotally mounted on said rear trailer part with means for moving
said tipping container on the rear chassis between a normally
lowered load carrying position on the rear chassis and an inclined
load tipping position on the rear chassis, characterised in that
the front suspension assembly includes an independent suspension
system for mounting the pair of front wheels on the front chassis
of the front tractor part.
49. An articulated dump truck as claimed in claim 48 wherein said
front suspension assembly is an independent suspension module
mounted on the front chassis.
50. An articulated dump truck as claimed in claim 49 wherein said
independent suspension module includes an axle housing with means
for attachment to the front chassis, the two front wheels being
pivotally mounted at opposite sides of said axle housing for
vertical movement, each front wheel being mounted by one or more
suspension arms on the axle housing, each suspension arm being
pivotally connected to the axle housing and to a wheel carrier on
which the front wheel is rotatably mounted to allow vertical
movement of the wheel on the axle housing, and spring means mounted
between a suspension arm or the wheel carrier and the front chassis
to resist vertical wheel movement.
51. An articulated dump truck as claimed in claim 50 wherein a pair
of suspension arms are provided, namely an upper suspension arm and
a lower suspension arm which are vertically spaced-apart, each of
the upper suspension arm and the lower suspension arm having an
inner end and an outer end, the inner end of each suspension arm
being pivotally connected to the axle housing and the outer end of
each suspension arm being pivotally connected to the wheel
carrier.
52. An articulated dump truck as claimed in claim 48 wherein the
front suspension assembly includes a suspension unit for each front
wheel, said suspension unit having one or more suspension arms,
each suspension arm being pivotally connected to the front chassis
and to a wheel carrier on which the front wheel is rotatably
mounted to allow vertical movement of the front wheel on the front
chassis, and spring means mounted between a suspension arm or the
wheel carrier and the front chassis to resist vertical wheel
movement.
53. An articulated dump truck as claimed in claim 52 wherein a pair
of suspension arms are provided, namely an upper suspension arm and
a lower suspension arm which are vertically spaced-apart, each of
the upper suspension arm and the lower suspension arm having an
inner end and an outer end, the inner end of each suspension arm
being pivotally connected to the front chassis and the outer end of
each suspension arm being pivotally connected to the wheel
carrier.
54. An articulated dump truck as claimed in claim 51 wherein the
spring means includes a coil spring and associated damper housed
within the spring and mounted between a lower mounting bracket and
an upper mounting plate, the lower mounting bracket having a spring
holder with downwardly extending forked arms which engage the lower
control arm by means of a pivot pin, the upper mounting plate being
secured by bolts to the front chassis.
55. An articulated dump truck as claimed in claim 50 wherein a top
of the axle housing is bolted to an underside of the front
chassis.
56. An articulated dump truck as claimed in claim 50 wherein the
front chassis includes a pair of spaced-apart longitudinal members
interconnected by cross members, the axle housing being bolted to
an underside of cross members between the longitudinal members.
57. An articulated dump truck as claimed in claim 51 wherein pivot
pins are provided at each end of the suspension arms which
rotatably engage in complementary pivot blocks mounted on the wheel
carrier, on the axle housing or on the front chassis, the upper
suspension arm being I-shaped having a pair of laterally extending
pivot pins at each end which project forwardly and rearwardly of
the upper suspension arm to rotatably engage the pivot blocks, the
lower suspension arm being of wishbone construction and has a pair
of laterally extending pivot pins at an outer end which project
forwardly and rearwardly of the lower suspension arm to rotatably
engage associated pivot blocks on the wheel carrier, inwardly
extending fork arms of the lower suspension arm each having at
their inner end a laterally extending pivot pin which rotatably
engages an associated pivot block on the axle housing or front
chassis.
58. An articulated dump truck as in claim 48 wherein said tipping
load container does not extend substantially over the steer axis so
that the centre of gravity of the loaded container is normally
between the axes of rotation of the rear wheels or only slightly in
front of the axle closest to the steer axis.
59. An articulated dump truck as in claim 48 in which an anti-roll
bar is fitted to the front independent suspension.
60. An articulated dump truck as in claim 48 in which the front
wheels are steerable on the front chassis, sensing means to measure
one or more of the vehicle speed and the steer angles of the front
wheels and of the articulation joint and control means to apportion
steering action between the said front wheels and the articulation
joint.
61. An articulated dump truck as claimed in claim 60 having means
for locking articulation around the vertical steering axis.
62. An articulated dump truck as claimed in claim 60 having means
for locking the front wheel steering.
63. An articulated dump truck as claimed in claim 48 that includes
a motion control system having means for controlling operation of
the vehicle suspension system in response to pitch, roll or yaw
movement of the vehicle, wherein said means controls operation of
the tractor suspension system in response to pitch, roll or yaw
movement of the vehicle.
64. An articulated dump truck as claimed in claim 63 having a roll
control system which includes means for stiffening the suspension
in direct proportion to the amount of roll.
65. An articulated dump truck as claimed in claim 64 which includes
means for locking the suspension when a preset roll angle is
reached.
66. An articulated dump truck as claimed in claim 63 having a roll
control system which includes means for controlling operation of
the suspension system in response to the sensed turn angle between
the tractor and the trailer.
67. An articulated dump truck as claimed in claim 66 wherein the
roll control system includes means for sensing turning of the
tractor unit relative to the trailer unit and suspension locking
means operably connected to the sensing means to lock the
suspension when a preset turn angle is reached, and release the
suspension for normal operation below said preset turn angle.
68. An articulated dump truck vehicle, including: a front tractor
part connected to an associated rear trailer part by means of an
articulated coupling which is mounted between a rear end of the
tractor part and a front end of the trailer part, said articulated
coupling being operable to allow the front tractor part and the
rear trailer part to rotate relative to each other about a first
vertical axis, with steering means for turning the front tractor
part relative to the rear trailer part about said first vertical
axis for steering the vehicle, and said articulated coupling also
allowing the front tractor part and the rear trailer part to rotate
relative to each other about a second longitudinal axis of the
vehicle, the front tractor part having a front chassis, a pair of
front wheels being mounted by a front suspension assembly on the
front chassis, a prime mover mounted on said front tractor part and
driveably connected to at least one pair of wheels on the vehicle,
a vehicle driving station on said front tractor part with controls
for vehicle drive and steering, the rear trailer part having a rear
chassis, at least two pairs of rear wheels mounted by a rear
suspension assembly on the rear chassis, a tipping container
pivotally mounted on said rear trailer part with means for moving
said tipping container on the rear chassis between a normally
lowered load carrying position on the rear chassis and an inclined
load tipping position on the rear chassis, characterised in that
the front suspension assembly includes an independent suspension
system for mounting the pair of front wheels on the front chassis
of the front tractor part, said front suspension assembly being an
independent suspension module mounted on the front chassis.
69. An articulated dump truck vehicle, including: a front tractor
part connected to an associated rear trailer part by means of an
articulated coupling which is mounted between a rear end of the
tractor part and a front end of the trailer part, said articulated
coupling being operable to allow the front tractor part and the
rear trailer part to rotate relative to each other about a first
vertical axis, with steering means for turning the front tractor
part relative to the rear trailer part about said first vertical
axis for steering the vehicle, and said articulated coupling also
allowing the front tractor part and the rear trailer part to rotate
relative to each other about a second longitudinal axis of the
vehicle, the front tractor part having a front chassis, a pair of
front wheels being mounted by a front suspension assembly on the
front chassis, a prime mover mounted on said front tractor part and
driveably connected to at least one pair of wheels on the vehicle,
a vehicle driving station on said front tractor part with controls
for vehicle drive and steering, the rear trailer part having a rear
chassis, at least two pairs of rear wheels mounted by a rear
suspension assembly on the rear chassis, a tipping container
pivotally mounted on said rear trailer part with means for moving
said tipping container on the rear chassis between a normally
lowered load carrying position on the rear chassis and an inclined
load tipping position on the rear chassis, the front suspension
assembly including an independent suspension system for mounting
the pair of front wheels on the front chassis of the front tractor
part, the front suspension assembly includes a suspension unit for
each front wheel, said suspension unit having a pair of suspension
arms, each suspension arm being pivotally connected to the front
chassis and to a wheel carrier on which the front wheel is
rotatably mounted to allow vertical movement of the front wheel on
the front chassis, and spring means mounted between a suspension
arm or the wheel carrier and the front chassis to resist vertical
wheel movement, the suspension arms comprising, namely an upper
suspension arm and a lower suspension arm which are vertically
spaced-apart, each of the upper suspension arm and the lower
suspension arm having an inner end and an outer end, the inner end
of each suspension arm being pivotally connected to the front
chassis and the outer end of each suspension arm being pivotally
connected to the wheel carrier.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to an articulated dump truck (ADT)
which consists of two vehicle chassis frames mounted on wheels and
linked by a steerable articulation joint, with a tipping load
container mounted pivotally on the rear chassis while the front
chassis carries the cab and prime mover. The articulation joint
allows rotation around two axes, namely a first vertical axis and a
second longitudinal axis. The rear chassis is mounted on four
wheels, two wheels being displaced longitudinally on each side,
while the front chassis is mounted on two wheels.
[0002] The vehicle is steered by controlling the relative rotation
of the chassis frames around the vertical axis at the articulation
joint, usually by means of hydraulic rams. The articulated joint
also incorporates a large bearing with axis of rotation along the
longitudinal axis of either the front or the rear chassis frame in
order to decouple the roll of the front and rear chassis frames.
This confers advantage in traversing rough terrain by allowing the
front and rear chassis frames to maintain better wheel contact with
the ground.
[0003] Existing designs of ADT provide limited or no roll
compliance in the front vehicle suspension, relying mostly on this
rotational degree of freedom around the longitudinal axis augmented
by tyre compliance, to maintain wheel contact when traversing rough
terrain. This approach works well at low speeds. However, at higher
speeds single wheel bumps are accompanied by a severe dynamic
rolling action of the entire front vehicle body about the
longitudinal axis of the articulation joint. Also, due to the high
driving position typical of these vehicles, this rolling action
subjects the driver to significant lateral accelerations resulting
in an uncomfortable ride. Thus the vehicle is effectively limited
to low speed operation over rough terrain and this in turn limits
productivity.
[0004] A suspension system is desirable in order to isolate the
chassis frame and hence the driver from road inputs. It also helps
to keep good contact between the wheels and the ground thus
ensuring good traction at all times. Ideally for good ride the
suspension should have a long wheel travel and a low natural
frequency. This is achieved by using soft springs. Unsprung mass
should also be minimised. Unfortunately, soft springs may result in
excessive roll of the vehicle when cornering. Hence there is a
trade off between the ride and handling properties of the vehicle.
This trade off is particularly acute for ADTs. Inherent with the
articulated steering system is the disadvantage that, as the
vehicle turns, the outside wheel of the front chassis frame moves
closer to the centreline of the load carrying rear chassis frame
and consequently bears more of the front axle load. This
significantly reduces the roll resistance of the front chassis
frame giving rise to larger roll angles when cornering. This
reduces stability and impacts on driver confidence.
[0005] The current state of the art for ADT front suspensions falls
broadly into three groups. The most basic system comprises a beam
axle mounted on a leading arm or frame pivotally connected to the
front chassis frame on an axis parallel to the axle. This allows
the wheels to move predominantly vertically but allows almost no
suspension compliance in roll. Consequently this suspension can be
fitted with very soft springs. A bump affecting both front wheels
simultaneously can be negotiated with a high degree of comfort due
to the soft springs. Single wheel bumps, however, are accompanied
by a severe rolling action of the front chassis frame about the
longitudinal axis of the articulation joint.
[0006] A second class of front suspension system comprises a beam
axle mounted on a leading arm or frame pivotally connected to the
front chassis frame by a ball joint with single or multiple control
arms. The ball joint permits rolling of the front chassis relative
to the front axle. The ability of the axle to roll relative to the
chassis reduces the amount of lateral acceleration experienced by
the driver when traversing single wheel bumps. However the
suspension springs are now required to counter the tendency to roll
when cornering. Increasing spring stiffness to counter excessive
roll raises the suspension natural frequency and reduces suspension
travel thus detracting from ride quality. Another disadvantage of
this system is the large unsprung mass inherent in this design.
[0007] The third class of front suspension system used in state of
the art ADTs has separate wheel carriers mounted on leading arms
which are resiliently pivoted on the front chassis frame The
leading arms have a rod and tube crosstie which keeps the wheels on
the same axis while allowing rotation of one end of the crosstie
with respect to the other. Combined with the compliance of the
leading arm pivots, this allows the wheels a limited degree of
articulation relative to each other in response to a single wheel
bump.
[0008] In summary, none of the three presently used front
suspension systems is able to offer drivers acceptable levels of
both vertical and roll stability during operation at elevated
forward speeds.
[0009] In the prior art GB1008045 (General Motors) discloses a
dumper vehicle comprising a front and a rear chassis frame each
supported on a pair of driven wheels and hinged together about a
vertical steer axis located between the axes of rotation of the
pairs of wheels and a tippable body which is pivoted on the rear
frame and which, in its untipped position, extends over the steer
axis, the centre of gravity of the body being located, in said
untipped position, substantially mid-way between the said axes of
rotation. The front and rear chassis frames only pivot about a
single (vertical) axis for steering and thus this vehicle suffers
from the rolling difficulties mentioned above.
[0010] As the vehicle has only four wheels the centre of gravity of
the tippable body lies between the front and rear axles,
substantially mid-way between the front and rear wheels putting
considerable loading on the articulated connector.
[0011] GB1008045 (General Motors) further discloses such a dumper
vehicle in which each pair of wheels is mounted on an axle
connected to the associated chassis frame by a resilient suspension
system so as to allow the axle to oscillate relative to the frame
about a longitudinal axis. This appears to be the arrangement
depicted in FIGS. 1 and 2, but it is not clear from the description
how this is implemented. It also mentions the possibility that the
wheels could be independently mounted on resilient suspension
systems However this arrangement is not described and this proposal
appears to have been incorporated without consideration of
practical implementation. In practice, implementation of
independent suspension would be difficult or impossible on a
vehicle as shown in FIGS. 1 and 2 of GB1008045 because the large
twin wheels shown, allow insufficient room to successfully install
independent suspension.
[0012] U.S. Pat. No. 5,147,011 (Hvolka) describes a `uni-body`
digging service vehicle having an articulated chassis with a
two-wheel front chassis frame plus four-wheel rear chassis frame.
Here again, as with GB1008045, the articulation between front and
rear sections occurs solely about a single vertical axis for
steering purposes.
[0013] U.S. Patent Application Publication No. US2003/0094775 also
discloses a forestry vehicle having a two-plus-four articulated
chassis with articulation between front and rear segments only
about a single vertical axis for steering purposes.
[0014] U.S. Pat. No. 3,414,072 (Hodges) discloses a highly
maneuverable articulated vehicle, particularly for military use,
comprising front and rear units each mounted on four wheels and
interconnected by an articulated coupling. This construction
facilitates travel over rough terrain as well as normal highway
use. The driver and other personnel or cargo are carried in the
rear unit.
SUMMARY OF THE INVENTION
[0015] According to the invention there is provided an articulated
dump truck vehicle, including: [0016] a front tractor part
connected to an associated rear trailer part by means of an
articulated coupling which is mounted between a rear end of the
tractor part and a front end of the trailer part, [0017] said
articulated coupling being operable to allow the front tractor part
and the rear trailer part to rotate relative to each other about a
first vertical axis, with steering means for turning the front
tractor part relative to the rear trailer part about said first
vertical axis for steering the vehicle, and said articulated
coupling also allowing the front tractor part and the rear trailer
part to rotate relative to each other about a second longitudinal
axis of the vehicle, [0018] the front tractor part having a front
chassis, a pair of front wheels being mounted by a front suspension
assembly on the front chassis, [0019] the rear trailer part having
a rear chassis, at least two pairs of rear wheels mounted by a rear
suspension assembly on the rear chassis, [0020] a prime mover
mounted on said front tractor part and driveably connected to at
least one pair of wheels on the vehicle, [0021] a vehicle driving
station on said front tractor part with controls for vehicle drive
and steering, [0022] a tipping container pivotally mounted on said
rear trailer part with means for moving said tipping container on
the rear chassis between a normally lowered load carrying position
on the rear chassis and an inclined load tipping position on the
rear chassis, [0023] characterised in that the front suspension
assembly includes an independent suspension system for mounting the
pair of front wheels on the front chassis of the front tractor
part.
[0024] The invention provides an independent suspension system on
the front chassis of an articulated dump truck of the type
described herein. Before the present invention there has been no
disclosure of this type of dump truck vehicle having in combination
with an articulated joint which allows rotation about both vertical
and longitudinal axes an independent front suspension system. This
may be because of the significant difficulty in packaging a
sufficiently robust independent suspension in a dump truck vehicle
of this type and the failure to recognise the significant benefits
which such a system confers. The fact that the longitudinal bearing
in the articulation joint decouples the front and rear chassis
frames in roll appears to have lead those versed in the art to
discount the utility of providing increased roll compliance in the
front suspension in order to improve the ride performance of the
vehicle. When such compliance has been provided, relatively stiff
springs have been employed to provide sufficient resistance to roll
movements induced in cornering. Independent suspension on the other
hand maximises the anti-roll moment for a given spring rate
measured at the wheel because the springs effectively act at the
wheels rather than at the spring location and consequently have a
larger effective moment arm. The invention minimises lateral
vibration of the cab and thus allows a driver to comfortably
operate at higher speeds over rough ground with consequent increase
in productivity. The modular design disclosed herein enables the
invention to be carried out in a particularly robust and affordable
manner.
[0025] In one embodiment of the invention front suspension assembly
is an independent suspension module mounted on the front
chassis.
[0026] In another embodiment said independent suspension module
includes an axle housing with means for attachment to the front
chassis, the two front wheels being pivotally mounted at opposite
sides of said axle housing for vertical movement, each front wheel
being mounted by one or more suspension arms on the axle housing,
each suspension arm being pivotally connected to the axle housing
and to a wheel carrier on which the front wheel is rotatable
mounted to allow vertical movement of the wheel on the axle
housing, and spring means mounted between a suspension arm or the
wheel carrier and the front chassis to resist vertical wheel
movement.
[0027] In another embodiment a pair of suspension arms are
provided, namely an upper suspension arm and a lower suspension arm
which are vertically spaced-apart, each of the upper suspension arm
and the lower suspension arm having an inner end and an outer end,
the inner end of each suspension arm being pivotally connected to
the axle housing and the outer end of each suspension arm being
pivotally connected to the wheel carrier.
[0028] In a further embodiment the front suspension assembly
includes a suspension unit for each front wheel, said suspension
unit having one or more suspension arms, each suspension arm being
pivotally connected to the front chassis and to a wheel carrier on
which the front wheel is rotatably mounted to allow vertical
movement of the front wheel on the front chassis, and spring means
mounted between a suspension arm or the wheel carrier and the front
chassis to resist vertical wheel movement.
[0029] In another embodiment a pair of suspension arms are
provided, namely an upper suspension arm and a lower suspension arm
which are vertically spaced-apart, each of the upper suspension arm
and the lower suspension arm having an inner end and an outer end,
the inner end of each suspension arm being pivotally connected to
the front chassis and the outer end of each suspension arm being
pivotally connected to the wheel carrier.
[0030] In another embodiment the spring means includes a coil
spring.
[0031] In another embodiment the spring means includes a pair of
coil springs each having a lower end pivotally connected to the
lower suspension arm and an upper end connected to the front
chassis, the upper suspension arm extending between said pair of
coil springs. Preferably an associated damper is provided with each
spring.
[0032] In another embodiment each spring includes a coil spring and
associated damper housed within the spring and mounted between a
lower mounting bracket and an upper mounting plate, the lower
mounting bracket having a spring holder with downwardly extending
forked arms which engage the lower control arm by means of a pivot
pin, the upper mounting plate being secured by bolts to the front
chassis.
[0033] In a further embodiment a top of the axle housing is bolted
to an underside of the front chassis.
[0034] In another embodiment the front chassis includes a pair of
spaced-apart longitudinal members interconnected by cross members,
the axle housing being bolted to an underside of cross members
between the longitudinal members.
[0035] In another embodiment pivot pins are provided at each end of
the control arms which rotatably engage in complementary pivot
blocks mounted on the wheel carrier, on the axle housing or on the
front chassis.
[0036] In another embodiment the upper suspension arm is I-shaped
having a pair of laterally extending pivot pins at each end which
project forwardly and rearwardly of the upper suspension arm to
rotatably engage the pivot block.
[0037] In another embodiment the lower suspension arm is of
wishbone construction and has a pair of laterally extending pivot
pins at an outer end which project forwardly and rearwardly of the
lower suspension arm to rotatably engage associated pivot blocks on
the wheel carrier, inwardly extending fork arms of the lower
suspension arm each having at their inner end a laterally extending
pivot pin which rotatably engages an associated pivot block on the
a)de housing or front chassis.
[0038] In another embodiment said tipping load container does not
extend substantially over the steer axis so that the centre of
gravity of the loaded container is normally between the axes of
rotation of the rear wheels or only slightly in front of the axle
closest to the steer axis
[0039] In another embodiment an ant-roll bar is fitted to the front
independent suspension.
[0040] In another embodiment the front wheels are steerable on the
front chassis.
[0041] In another embodiment there is provided sensing means to
measure one or more of the vehicle speed and the steer angles of
the front wheels and of the articulation joint and control means to
apportion steering action between the said front wheels and the
articulation joint.
[0042] In another embodiment articulation around the vertical
steering axis may be locked.
[0043] In a further embodiment the front wheel steering may be
locked.
[0044] In another embodiment there is provided a motion control
system having means for controlling operation of the vehicle
suspension system in response to pitch, roll or yaw movement of the
vehicle.
[0045] In another embodiment said means controls operation of the
tractor suspension system in response to pitch, roll or yaw
movement of the vehicle.
[0046] In a further embodiment there is provided a roll control
system having means for controlling operation of the vehicle
suspension system in response to roll of the vehicle.
[0047] In another embodiment said means controls operation of the
tractor suspension system in response to roll of the tractor
unit.
[0048] In another embodiment the roll control system includes means
for stiffening the suspension in direct proportion to the amount of
roll.
[0049] In a further embodiment there is provided means for locking
the suspension when a preset roll angle is reached.
[0050] In another embodiment the roll control system includes means
for controlling operation of the suspension system in response to
the sensed turn angle between the tractor and the trailer.
[0051] In a further embodiment the roll control system includes
means for sensing turning of the tractor unit relative to the
trailer unit and suspension locking means operably connected to the
sensing means to lock the suspension when a preset turn angle is
reached, and release the suspension for normal operation below said
preset turn angle.
[0052] According to another embodiment there is provided an
articulated dump truck including a two-wheel tractor unit connected
to an associated four-wheel trailer unit by an articulating hitch
connector which allows relative rotation of the tractor unit and
the trailer unit about a vertical axis and about a longitudinal
axis of the dump truck, steering means for relative rotation of the
tractor unit and the trailer unit about said vertical axis for
steering the dump truck, said tractor unit having an independent
suspension system.
[0053] In a further embodiment the suspension system for the front
tractor unit is a fully independent suspension system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] The invention will be more clearly understood by the
following description of some embodiments thereof, given by way of
example only, with reference to the accompanying drawings, in
which:
[0055] FIG. 1 is an elevational view of an articulated dump truck
according to the invention;
[0056] FIG. 2 is a plan view of the articulated dump truck;
[0057] FIG. 3 is an elevational view of another articulated dump
truck according to a second embodiment of the invention;
[0058] FIG. 4 is a plan view of the articulated dump truck shown in
FIG. 3;
[0059] FIG. 5 is a front elevational view of the articulated dump
truck shown in FIG. 3;
[0060] FIG. 6 is a rear elevational view of the articulated dump
truck shown in FIG. 3;
[0061] FIG. 7 is a detail, partially exploded, perspective view of
a modular independent suspension system for a front tractor part of
the articulated dump truck shown in FIG. 3;
[0062] FIG. 8 is another perspective view of the front independent
suspension system;
[0063] FIG. 9 is an elevational view of the front independent
suspension system;
[0064] FIG. 10 is another elevational view similar to FIG. 9
showing the front independent suspension system in another position
of use;
[0065] FIG. 11 is another elevational view similar to FIG. 9
showing the front independent suspension system in a further
position of use;
[0066] FIG. 12 is a detail perspective view showing the modular
front independent suspension system of FIG. 7 mounted on a front
chassis of the front tractor part of the articulated dump truck of
FIG. 3;
[0067] FIG. 13 is a detail partially sectioned elevational view
showing the modular front independent suspension system of FIG. 7
mounted on the chassis of the front tractor part of the articulated
dump truck of FIG. 3;
[0068] FIG. 14 is an elevational view of the modular front
independent suspension system;
[0069] FIG. 15 is a plan view of the modular front independent
suspension system;
[0070] FIG. 16 is a perspective view of another modular independent
front suspension system for the articulated dump truck;
[0071] FIG. 17 is a diagrammatic plan view of another articulated
dump truck incorporating a roll control system according to another
embodiment of the invention;
[0072] FIG. 18 is a diagrammatic elevational view of the
articulated dump truck shown in FIG. 17; and
[0073] FIG. 19 is a schematic illustration of a suspension system
for the articulated dump truck shown in FIG. 17.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0074] Referring to the drawings, and initially to FIGS. 1 and 2
thereof, there is illustrated an articulated dump truck vehicle
according to the invention indicated generally by the reference
numeral 1. The articulated dump truck 1 includes a front tractor
unit 2 connected to an associated rear trailer unit 3 by an
articulated coupling 4. The front tractor unit 2 is provided with
an independent suspension system for mounting wheels 5 on a front
chassis 6 of the front tractor unit 2.
[0075] The front tractor unit 2 has a cab 7 within which are
located controls for driving and operation of the articulated dump
truck 1.
[0076] The rear trailer unit 3 has a rear chassis 10 mounted on two
pairs of wheels 11. A tipping container 12 is pivotaly mounted on
the rear chassis 10 on which it can be tipped as shown in broken
outline in FIG. 1 by means of rams 14 at each side.
[0077] The articulated coupling 4 can rotate about longitudinal
axis X and vertical axis 22 of the truck 1 but is unable to rotate
about a transverse axis of the truck 1. Steering is achieved by the
forced articulation of the articulated coupling 4 about its
vertical axis 22 by means of steering rams 20 extending between the
front tractor unit 2 and rear trailer unit 3. These rams 20 are
operable to pivot the front tractor unit 2 and rear trailer unit 3
about a vertical pivot 22 of the articulated coupling 4.
[0078] The tipping load container 12 in its untipped position does
not extend substantially over the steer axis 22 so that the centre
of gravity of the loaded container 12 is normally between the axes
of rotation of the rear wheels 11 or only slightly in front of the
middle axle.
[0079] It will be appreciated that any suitable independent
suspension system may be employed for the tractor unit 2.
[0080] Referring now to FIGS. 3 to 13 of the drawings there is
illustrated another articulated dump truck vehicle according to a
second embodiment of the invention indicated generally by the
reference numeral 30. Parts similar to those described previously
have been assigned the same reference numerals. A modular
independent front suspension system indicated generally by the
reference numeral 32 for mounting the front wheels 5 on the front
chassis 6 of the front tractor unit 2 is shown in FIGS. 7 to 15.
This modular independent front suspension system 32 has an axle
housing 33 which is bolted to the front chassis 6 and from which
are hung the front wheels 5.
[0081] The axle housing 33 has a bottom 34 with upright front wall
35, rear wall 36 and side walls 37, 38. A top 39 of the axle
housing 33 has a plurality of mounting holes 40 for reception of
mounting bolts (not shown) which bolt the axle housing 33 to the
front chassis 6. The axle housing 33 may be a casting or may be of
fabricated construction.
[0082] At each side of the axle unit 33 a suspension unit 41
supports a wheel hub unit 42 which carries one of the front wheels
5. The wheel hub unit 42 is mounted for vertical movement by means
of a pair of control arms of the suspension unit 41, namely an
upper control arm 44 and a lower control arm 45, both of which
extend between and are pivotally mounted on both the axle housing
33 and the hub unit 42. A drive shaft 46 is mounted between the
upper control arm 44 and lower control arm 45 extending between the
axle housing 33 and the hub unit 42 for drive transmission to the
front wheels 5.
[0083] Each upper suspension control arm 44 has an outer end 48
with laterally extending pivot pins 49 which engage with associated
pivot blocks 50 on an inside of the hub unit 42. Similarly, an
inner end 52 of the upper control arm 44 has laterally extending
pivot pins 53 which rotatably engage in associated pivot blocks 55
mounted on an exterior of the side wall 37, 38 of the axle housing
33. Each pivot block 55 is secured by screw bolts 56 on a
complementary mounting plate 57 on the side wall 37, 38 of the axle
housing 33. The pivot pins 49, 53 at the outer end 48 and the inner
end 52 of the upper control arm 44 have parallel pivot axes. A
striker plate 58 on top of the upper control arm 44 is engagable
with an associated bump stop 59 which is mounted on the front
chassis 6.
[0084] Each lower suspension control arm 45 is of wishbone
construction. Pivot pins 62 at an outer end 61 of the lower control
arm 45 engage associated pivot blocks 63 on an inner face of the
hub 42. This pivot arrangement is similar to that for the upper
control arm 44. Each pivot block 63 has a split housing 64 within
which is mounted a seal 65 which seals between an inner end of the
pivot block 63 and the pivot pin 62. The pivot pin 62 is supported
in a bush 66 retained within the pivot block 63 by means of a
washer 67, shim 68 and the end cover 69 of the pivot block 63. The
end cover 69 is secured on the body 64 of the pivot block 63 by
mounting bolts 70. Inwardly extending fork arms 72, 73 have at an
inner end 74 of each fork arm 72, 73 a pivot pin which rotatably
engages within an associated pivot block 75 as previously
described. The pivot pins at inner and outer ends of the lower
control arm 45 have parallel pivot axes.
[0085] A pair of spring and damper assemblies 78 each have a lower
end 79 pivotally mounted on one of the wishbone arms 72, 73 and an
upper end 80 which is attached to the front chassis 6. FIG. 9 shows
the springs and suspension arms in a neutral position. FIG. 10
shows the suspension arms and spring assembly in full bump position
at one side of the axle housing 33 and FIG. 11 shows the same
suspension arms and spring assemblies in full rebound position.
[0086] FIG. 12 shows the spring and damper assembly 78 in more
detail. A coil spring 82 and associated damper 83 housed within the
spring 82 are mounted between a lower mounting bracket 84 and an
upper mounting plate 85. The lower mounting bracket 84 has a spring
holder 86 with downwardly extending forked arms 87 which engage
with the lower control arm 45. A pivot pin 88 engages associated
through holes 89 in said arms 87 and a through hole 90 in the lower
control arm 45 to pivotally secure the lower end 79 of the spring
and damper assembly 78 on the lower control arm 45. The upper
mounting plate 85 is secured by bolts 93 to a laterally extending
horizontal mounting flange 94 on the front chassis 6 above the
suspension control arms 44, 45 with interposed spacer plates 92 if
required.
[0087] It will be appreciated that any suitable spring means may be
provided, for example single or multiple coil springs, hydro
pneumatic elements or other spring arrangements.
[0088] The front chassis 6 has a pair of spaced-apart longitudinal
members 96 interconnected by cross members 97. The axle housing 33
is bolted to an underside of some of the cross members 97. Cab
mounting posts 98 project upwardly to receive and support the cab 7
of the vehicle. A pivot mounting frame 99 forming part of the
articulated coupling 4 is provided at a rear end of the front
chassis 6 and has vertically spaced-apart mounts 100 for pilot pins
22 of the articulated coupling 4. Support brackets 102 for
attachment of the steering rams 20 are also provided at each side
of the front chassis 6.
[0089] A drive assembly (not shown) is mounted within the axle
housing 33. A drive input flange 110 (FIG. 15) at a rear of the
axle housing 33 connects the drive assembly to a prime mover
mounted on the front chassis 6. The drive assembly transmits drive
through the drive shafts 46 which extend laterally from the axle
housing 33 to the wheels 5.
[0090] The articulated coupling 4 essentially has two
interconnected parts, namely a first part mounted on one of the
front chassis 6 and rear chassis 10 and a second part mounted on
the other of the front chassis 6 and the rear chassis 10. The first
part is fixed on one chassis 6, 10 and interconnected with the
second part by the vertical pivot 22. The second part is rotatably
mounted on the other chassis 6, 10 for rotation about a
longitudinal axis of said other chassis 6, 10. Steering rams 20 are
provided for relative rotation of both coupling parts about the
vertical pivot 22.
[0091] Referring now to FIG. 16 there is shown another modular
independent suspension system 120 for the dump truck 30. This is
largely similar to the suspension system of FIGS. 7 to 15 and like
parts are assigned the same reference numerals. In this case the
suspension system 120 further includes an antiroll bar 121 which
extends between and interconnects the suspension units 41 at
opposite sides of the axle unit 33. The anti-roll bar 121 is
rotatably mounted in associated bushings 122 secured by mounting
brackets 123 on the front wall 35 of the axle unit 33.
[0092] Referring to FIGS. 17 to 19 of the drawings, there is
illustrated another articulated dump truck according to another
embodiment of the invention indicated generally by the reference
numeral 130. The dump truck 130 comprises a tractor unit 132
sitting on a single non-steering axle with wheels 133. The tractor
unit 132 is connected to an associated trailer unit 135 having an
open topped container 136 mounted on a chassis 137 with wheels 138.
The tractor unit 132 is connected to the trailer unit 135 by means
of an articulating hitch indicated generally by the reference
numeral 140. The hitch 140 is free to rotate about longitudinal and
vertical axes of the dump truck 130 but is unable to rotate about a
transverse axis of the dump truck 130. Steering is achieved by the
forced articulation of the hitch 140 about its vertical axis
creating a turn angle between the tractor unit 132 and trailer unit
135. Turning of the tractor unit 132 relative to the trailer unit
135 is shown in broken outline in FIG. 17. A sensor 142 mounted at
the hitch 140 detects turning of the tractor unit 132 relative to
the trailer unit 135 and locks a suspension system of the tractor
unit 132 when a preset turning of the tractor unit 132 relative to
the trailer unit 135 is reached.
[0093] FIG. 19 schernatically shows a hydropneuratic suspension for
the tractor unit 132. This essentially comprises a right hand
hydropneumatic spring assembly indicated generally by the reference
numeral 152 operably connected to a right hand front wheel 133 of
the tractor unit 132. Similarly a left hand hydropneumatic spring
assembly 154 is operably connected to a left front wheel 133 of the
tractor unit 132. The hydropneumatic spring assemblies 152, 154 are
similar and essentially comprise a gas cylinder 155 having a gas
chamber 156 and oil chamber 157. A separator piston 158 divides the
gas cylinder 155 into the gas chamber 156 and oil chamber 157. An
oil line 159 connects through a restictor 160 and a lockout valve
162 with a pair of oil cylinders 164, 165 operably connected to the
associated wheel 133 for controlling vertical movement of the wheel
133.
[0094] Each lockout valve 162 is a solenoid operated valve having a
normally open position. A switch 166 associated with the sensor 142
is operable to supply power to close the lockout valve 162 when the
tractor unit 132 turns beyond a pre-set angle relative to the
trailer unit 135 as detected by the sensor 142. When closed the
lockout valve 162 isolates the oil cylinders 164, 165 from the gas
cylinder 155. When the lockout valve 162 is in the closed position
the oil cylinders 164, 165 are hydraulically locked and vertical
wheel travel is prevented.
[0095] The sensor 142 essentially comprises a proximity switch
mounted on the vertical axis of the hitch 140 the targets for the
proximity switch are mounted so that lockout only occurs for
turning of the tractor unit 132 relative to the trailer unit 135
beyond a pre-set angle.
[0096] The steer or turn angle at which lockout occurs is selected
to correspond to the maximum roll angle allowable for driver safety
and/or comfort. The roll effect is limited by locking the
suspension on the tractor unit 132 once the steer angle increases
beyond a specified angle. This angle is effectively equivalent to
the roll that would be experienced due to the centrifugal force,
but is also infinitely variable within specified limits.
[0097] The invention is not limited to the embodiments hereinbefore
described which may be varied in both construction and detail
within the scope of the appended claims.
* * * * *