Note: Descriptions are shown in the official language in which they were submitted.
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A DUMP VEHICLE
FIELD OF THE INVENTION
[0001] The present invention relates to dump vehicles, and more particularly
to
actuation systems mounted on dump vehicles for raising and lowering dump beds.
BACKGROUND
[0002] Various kinds of dump vehicles are used in agriculture, construction,
mining and
other industries. In general, such vehicles are used to, at one location,
receive materials
such as produce, soil, ore, gravel, and construction debris for transport and
off-loading to
another site. A common example of such a vehicle is a dump truck. Other
examples
iriclude dump trailers, sleds, hoppers and the like.
[0003] A typical dump truck includes a chassis with a dump bed mounted thereto
so that
the bed can receive materials to be transported while in a generally
horizontal position.
T'he dump bed is movably mounted to the chassis so that the materials received
can
subsequently be unloaded by rotating or tilting the bed, allowing the
materials to flow out
of the bed. Typically, such dump beds are hinge mounted with the hinge being
located
at a rearward portion of the chassis. The bed is tilted typically by a
hydraulic cylinder
located near a forward portion of the bed, causing the bed to rotate about the
hinge from
a horizontal position to a tilted position.
[0004] The hydraulic cylinder is pivotably mounted, directly or indirectly, to
the chassis
and to the dump bed so that as the cylinder is extended, the bed is pushed
upward and
pivots about its hinge. Such cylinders are generally powered by a PTO-driven
pump
which may be energized to pump oil from an onboard reservoir into the cylinder
to cause
it to extend, and a valving system is employed to permit oil to return to the
reservoir as
the cylinder retracts.
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[0005] Due to the nature of the material typically transported in dump trucks
and to the
terrain over which they operate, it is common to have unbalanced loads
experienced by
cylinders used in dump trucks. These unbalanced loads give rise to unwanted
bending
rnoments which may severely affect the performance of the dump truck.
[0006] One example of an unbalanced load is evident when the load is not
uniformly
distributed within the bed. For example, when hauling debris, the debris may
contain a
niixture of soil, concrete, steel, framing materials, stumps, tree limbs, and
leaves. A
heavy concrete slab that winds up in a load disposed near one side wall of the
dump
bed, otherwise filled with tree limbs and relatively light debris, will cause
a greater
downward force on that side of the bed. Typically the cylinder is positioned
near a
transverse center of the bed and must therefore resist not only the vertical
load but also
the bending moment due to the concrete slab being disposed near one side wall
of the
bed.
[0007] Another example of an unbalanced load is the condition that arises due
to
unlevel terrain. Even where the material loaded in the dump bed is uniformly
distributed
and of uniform density, if the dump truck is on a transverse incline while
dumping, side
loads will occur due to gravity.
[0008] The bending moments generated by side loads in such situations are
often very
clamaging to the hydraulic cylinder and to the pivotable connections of the
cylinder to the
ciump bed and chassis. The bending moments generated by side loads will tend
to bend
the cylinder. In the least troublesome case, such cylinder bending may result
in seal
ciamage to the cylinder that then results in oil leakage and reduced
performance. In the
rnore catastrophic case, the bending moment may result in cylinder failure by
breaking.
Generally, in hydraulic cylinder design and selection, cylinders may be
employed that
are significantly over-designed to resist the side load moments, and this adds
unwarranted cost to the dump vehicie.
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[0009] Even with robust cylinder design to resist bending moments, there is
the
irnportant issue of the pivotable connections of the cylinder to the bed and
to the chassis
or other support structure. Ultimately, it is these connections that must
carry not only the
axial load from the cylinder, but also the bending moment introduced by side
loads.
For example, the hydraulic cylinder used to actuate the dump vehicle typically
includes a
cylinder pivot bearing or sleeve that is journaled around a cross shaft
mounted in a
support structure. Side or lateral loads placed on the cylinder are
transmitted to the
bearing, and over time, these loads tend to distort the bearing, resulting in
a loose
connection with the cross shaft. This loose connection results in the dump bed
being
unstabie as it is raised or supported by the hydraulic cylinder.
SUMMARY OF THE INVENTION
[0010] The present invention discloses a dump vehicle comprising a chassis and
a
dump bed. The dump bed is pivotably mounted to the chassis and is movable
between
generally horizontal and inclined positions. A support structure secured to
the chassis
supports a cylinder that is pivotably attached thereto. The cylinder is
operable between
retracted and extended positions. A stabilizing structure is included for
laterally
stabilizing the cylinder as the cylinder moves between the retracted position
and the
extended position. In one embodiment, the stabilizing structure comprises a
pair of arms
vrith the telescoping cylinder extending generally between the arms. A
retainer extends
around the cylinder and is interconnected with the pair of arms.
[iD011] The present invention also discloses a dump vehicle with a chassis and
a dump
bed pivotally mounted thereto and movable between generally horizontal and
inclined
positions. The invention includes a stabilizer mounted adjacent the cylinder
for generally
laterally confining the cylinder as the cylinder moves between retracted and
extended
positions.
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[0012] The present invention further discloses a method of laterally
stabilizing a cylinder
utilized to actuate a dump bed on a vehicle chassis. The method comprises
constraining
the cylinder, connected between a support structure and the dump bed, to move
in a
plane that is generally perpendicular to the chassis. Constraining cylinder
movement
includes transmitting at least a portion of a lateral load imposed on the
cylinder to a
guide structure that is independent of the chassis and the dump bed.
[0013] Other objects and advantages of the present invention will become
apparent and
obvious from a study of the following description and the accompanying
drawings which
are merely illustrative of such invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 is a side view of a dump truck.
[0015] Figure 2 is a fragmentary pictorial view of a dump bed shown in a
tilted
configuration.
[0016] Figure 3 is a pictorial view illustrating a telescoping cylinder for
actuating the
dump bed and a stabilizer for stabilizing the telescopic cylinder.
[0017] Figure 4 is an elevational view illustrating the stabilizer and its
relationship with
the telescoping cylinder.
[0018] Figure 5 is an exploded pictorial view of one embodiment of the
stabilizer.
[0019] Figure 6 is a fragmentary cross sectional view taken through a portion
of the
stabilizer.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT
[0020] The present invention is directed to a dump vehicle, a typical example
of which is
the dump truck shown in Figure 1 and indicated generally by the numeral 100.
Dump
truck 100 is a wheeled vehicle comprising a chassis 110 mounted on at least
front and
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rear axles 112, 114. Wheels 116 support dump truck 100 and provide locomotive
traction for the dump truck. A cab 130 is disposed on a forward portion of
chassis 110,
and the cab is adjacent an engine compartment 132. Cab 130 includes an
operator
location and passenger compartment 134 which provides a protective environment
for
operators and passengers. Dump bed 140 is pivotably mounted on chassis 110 by
a
hinge 146 disposed on a rearward portion of the chassis. Dump bed 140 includes
a bin
140A in which to load materials to be hauled by dump truck 100. See Figure 2.
[0021] Tuming now to more particular aspects of the present invention, a
support
structure 200 is mounted on chassis 110. In one embodiment, the support
structure 200
is a subassembly that is mounted on the chassis 110. However, the support
structure
200 can be an integral part of the vehicle chassis. As shown in Figures 2 and
3, support
structure 200 includes a generally rectangular base weldment having a
hydraulic
reservoir 220 and a telescoping cylinder 300 disposed thereon. While hydraulic
reservoir 220 is not necessarily disposed on support structure 200, when the
reservoir is
a part of a hydraulic system dedicated solely to actuating cylinder 300, a
typical design
may locate the reservoir on the support structure. More particularly, support
structure
200 includes a pair of spaced apart longitudinal frame members 230, 232 welded
to two
spaced apart transverse frame members 242, 244. See Figure 3. In one
embodiment,
one or more of frame members 230, 232, 242, 244 may be formed from hot rolled
steel
angle having horizontal and vertical flanges indicated, for example, by the
numerals
230A, 230B in Figure 3. Note, as shown in Figures 2 and 3, that horizontal
flanges 230A
and 232A are tumed outwardly.
[0022] In one embodiment, support structure 200 is secured to chassis 110 with
chassis
mounting brackets 200A, 200B welded on the underside of flanges 230A, 232A.
Holes
200C disposed as shown in Figures 2 and 3 on brackets 200A, 200B align with
holes
drilled in chassis 110 and allow support structure 200 to be bolted to chassis
110.
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[0023] Brackets 252 are welded to rear-facing flange 242B of transverse frame
member
242. Safety supports 250 are connected by pivot pins 252A to support brackets
252 as
shown in Figures 1 and 2. In a typical operation, safety supports 250 are
supported on
chassis 110 when not in use. With dump bed 140 inclined, safety supports 250
may be
pivoted upward to engage receptacles (not shown) formed in or welded to an
underside
ofi the dump bed 140 to support the bed during repair and maintenance
procedures.
[0024] Tuming now to the cylinder pivot structure for pivotably connecting
cylinder 300
to support structure 200, the cylinder pivot structure includes a pair of
interior, spaced-
alpart, longitudinal brackets 260 secured between transverse members 242 and
244. In
one embodiment brackets 260 may be formed using hot rolled angle steel similar
to that
used for the frame members 230, 232. Each bracket 260 has an opening 262
disposed
in a vertical flange of bracket 260 such that the openings in the pair of
brackets are
aligned. A bearing sleeve 264 is aligned with each opening 262 on the pair of
brackets
260 and secured thereto. One or more ribs are secured to each bearing sleeve
264 and
biracket 260 to reinforce the cylinder pivot structure. Members 268 extend
angularly
from brackets 260. An access opening 234 is provided in flange 232B of
transverse
frame member 232 to permit inserting cylinder pivot shaft 350 as will be
described here
bielow.
[0025] Telescoping cylinder 300 comprises, in one embodiment a cylinder
connector
bearing or sleeve 330 and a rod connector bearing 340. Telescoping cylinder
300
further comprises one or more interior cylindrical elements 310 adapted to
sealably slide
within the cylinder and a cylinder rod 320 (Figure 2) adapted to slide
sealably within the
innermost cylindrical element 310. It is appreciated that when, in one
embodiment,
hydraulic oil is pumped into the interior of telescoping cylinder 300,
cylinder rod 330 and
cylindrical elements 310 extend telescopically as shown in Figures 2 and 4.
The use of
telescoping cylinder 300 in dump vehicle 100 provides, at least, the
advantages of a
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stable structure with high resistance against buckling and bending as well as
a compact
retracted profile.
[0026] As discussed below, stabilizer 400 is disposed adjacent cylinder 300
and moves
back and forth therewith as the cylinder is extended and retracted. Lateral
loads
experienced by the cylinder 300 are transferred to the stabilizer 400, which
in turn
transfers the lateral loads to support structure 200.
[0027] Stabilizer 400 includes a pair of angled arms 410 and a retainer 401.
Each arm
410 includes a lower end portion 410A and an upper end portion 410B. Each arm
is
tapered such that the arm becomes progressively smaller in cross-section from
lower
end portion 410A to upper end portion 410B. See Figure 5. Arms 410 are
transversely
aligned with cylinder 300 and extend generally downwardly and outwardly
relative to the
cylinder, as shown in Figures 2, 3, and 4. Lower end portions 410A are
pivotably
connected to support structure 200 as will be described in more detail below.
Upper end
portions 410B are disposed adjacent cylinder 300 and are connected to retainer
401,
which extends around the cylinder. Included on each upper end portion 410B is
a
receiver, indicated generally at 412, adapted to receive and connect to a
portion of
retainer 401. Receiver 412 includes a web 414, first flange 416, and second
flange 418.
'OJeb 414 includes an opening 414B for securing retainer 401 as will be
described herein.
[0028] Each arm 410 includes a bearing sleeve 419 disposed on lower end
portion
410A for pivotably mounting the arm onto shaft 350. It is appreciated that
each bearing
sleeve 419 is angled relative to its respective arm 410 consistent with the
angulation of
the arms as described above.
[I1029] Retainer 401 comprises a pair of yokes 420. Each yoke 420 comprises a
generally curved portion 422 and two faces 424. See Figure 5. Curved portions
422
form generally semi-circular sections. Faces 424 are disposed on opposite ends
of
curved portion 422 and are disposed generally perpendicular to the curved
portions.
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Each face 424 includes a boss 424A formed thereon and an opening 424B that
extends
through the face and the boss. Each face 424 further includes first and second
edges
426, 428 wherein the angle between the edges approximately matches the angle
between flanges 416 and 418 of receiver 412.
[0030] Yokes 420 are disposed opposite each other such that opposing curved
portions
422 form an opening for receiving and constraining cylinder 300 as shown in
Figure 3.
The opening formed by yokes 420 is sized to provide a generally loose fit
around
cylinder 300. Faces 424 of opposed yokes 420 sandwich webs 414 of arms 410.
See
Figure 6. Bosses 424A protrude into openings 414B such that in each opening,
bosses
projecting from faces 424 oppose each other and openings therein align.
Further, edges
426 and 428 of faces 424 abut flanges 416 and 418 of receivers 412. Connector
bolts
421 A extend through openings 424B, and with washers 421 B, 421 C and nuts 421
D,
compressively secure yokes 420 to arms 410. It is appreciated that the
engagement of
bosses 424A with openings 414B and the engagement of edges 426, 428 with
flanges
416, 418 provide secure connections between yokes 420 and arms 410 that
protect
bolts 421A from shear forces. In other words, bosses 424A and flanges 416, 418
carry a
portion of the lateral load imposed on telescoping cylinder 300.
[0031] Telescoping cylinder 300 extends between the support structure 200 and
dump
bed 140. Cylinder connector bearing 330 is aligned and secured between
brackets 260
with cylinder pivot shaft 350 inserted through the connector bearing. Cylinder
pivot shaft
350 is inserted through access opening 234 and into bearing sleeves 264 and
cylinder
connector bearing 330. Washers 352 and cotter keys 354 may be inserted to
secure
cylinder connector shaft 350. In the embodiment illustrated herein, the shaft
350 is fixed
in the support structure 200 and the arm 410 and cylinder 300 rotate about the
transverse axis of the shaft. Portions of shaft 350 extend outwardly from
brackets 260 to
receive arms 410. Similarly, rod connector bearing 340 is pivotably connected
to dump
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bed 140 with a rod connector bracket 142 disposed on the underside of the dump
bed
and a rod pivot pin 142A. See Figure 1. Hydraulic connections from the
hydraulic power
system, including reservoir 220, are made to telescoping cylinder 300 by
conventional
means.
[0032] Stabilizer 400 is pivotably mounted on shaft 350 and pivots back and
forth with
telescoping cylinder 300. As seen in Figure 3, lower end portions 410A of arms
410 are
secured to the outer end portions of shaft 350 such that the stabilizer and
telescoping
cylinder 300 pivot about a common axis.
[0033] Considering now the operation of dump truck 100, and in particular the
stabilization of cylinder 300 by stabilizer 400, it is appreciated that as
cylinder 300 is
extended, dump bed 140 moves from a generally horizontal position to an
inclined
position. As has been described heretofore, unevenly distributed loads in dump
bed 140
arid/or operation of dump truck 100 on uneven terrain may cause potentially
destructive
side loads to be applied to telescoping cylinder 300. These side loads tend to
cause
cylinder 300 to deflect laterally. This lateral deflection is potentially
damaging to the rod
connector bracket 142, rod connector pin 142A, telescoping cylinder 300,
cylinder
connector bearing 330, cylinder pivot brackets 260, and shaft 350. Stabilizer
400
absorbs and transmits portions of the side loads imposed on the cylinder 300
to the
support structure 200, and the stabilizer constrains the cylinder to move in a
generally
vertical plane aligned with a longitudinal axis of chassis 110 thereby
preventing
damaging lateral deflection of the cylinder
[0034] The present invention may, of course, be carried out in other specific
ways than
those herein set forth without departing from the scope and the essential
characteristics
of the invention. The present embodiments are therefore to be construed in all
aspects
as illustrative and not restrictive and all changes coming within the meaning
and
equivalency range of the appended claims are intended to be embraced therein.
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