Note: Descriptions are shown in the official language in which they were submitted.
CA 02216497 1997-09-24
TRUCK MOUNTED PAYLOAD LOADING AND UNLOADING APPARATUS AND
METHOD
BACKGROUND OF THE INVENTION
This invention relates generally to removable truck-
mounted payloads, and more particularly to a tilting bed
method and apparatus for loading and unloading such
payloads.
A number of mechanisms have been invented to simplify
the operation of loading and unloading payloads from trucks
and the payload carrying beds thereof. Many such mechanisms
are directed to truck-beds that tilt about a bed pivot axis
located near the aftmost portion of the truck frame. The
bed pivot joint is so located because, with this
configuration, the truck frame is less likely to interfere
with the tilting bed during the tilting operation.
Typically, in trucks having such mechanisms, the
forwardmost end of the bed is mechanically raised, while the
opposing aft end simultaneously lowers toward the ground.
In this type of tilting bed construction, the loading and
unloading procedure is facilitated when the aft end of the
tilting bed, or an extension thereof, is lowered to a point
where it contacts the ground in the tilting procedure.
Generally, to achieve this result, the aft end of most
tilting beds cantilever or overhang a substantial distance
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CA 02216497 1997-09-24
rearward from the bed pivot joint which, as noted above, is
typically located at the rear of the frame. In this way,
the further the tilting bed cantilevers past the frame, the
closer to the ground the aft end thereof travels for a given
amount of tilting bed rotation about the bed pivot joint.
The maximum distance the aft end can cantilever, however, is
often limited.
More specifically many small, light trucks have a
li.mited "overall" bed length because of their moderate load
carrying capacity. In addition, for stability reasons,
lilght trucks are designed with the rear wheels placed as far
ta the rear as possible to achieve the longest wheel base
that can fit within the frame. However, for reasons of
de:sign, a vehicle frame must extend some distance past the
rear wheels to accommodate the components that connect the
rear wheels to the frame. Thus, because the overall bed
leng'th of light trucks is limited, and a maximum wheel base
is desired, the amount of bed extension past the frame, and
thezefore past the wheels, must be minimized.
In contrast, however, the aft end of the tilting bed
musat often extend a large distance past the frame to enable
the aft end of the tilting bed to reach the ground when the
bed is tilted. Accordingly, there is a trade-off between
miriimizing the distance the tilting bed can extend past the
ve?isicle frame, and maximizing the wheel base length.
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CA 02216497 1997-09-24
To overcome this, many early designs incorporated
folding extensions that extend from the aft end of the
tilting bed. This type of design, however, is somewhat more
complicated, expensive and to build and install, and lacks
flexibility. For example, in 1973 U.S. Patent 3,712,491
issued disclosing a dump and transport vehicle that included
a tilting bed having an aft end that lowered to a point
substantially above the ground, and a tailgate portion that
unfolded therefrom to form a planar extension that extends
to the ground. This design requires additional mechanically
controlled components to control the planar extension.
Similarly, in 1976 U.S. Patent 3,964,626 issued disclosing a
truck for handling containers. The 1626 design includes a
retractable extension having wheels to permit the extension
to roll on the ground. Further in 1982 U.S. Patent
4,319,658 issued showing a tilting deck vehicle that
included a hydraulically operated apron that extended from
the tilting deck to the ground.
Later designs included U.S. Patent 4,595,210 issued in
1986 to Groeing disclosing a fruit bin trailer that included
an aft end that cantilevered well beyond the rear wheels of
the vehicle. Although this design permitted the aft end to
reach the ground, the wheel base of the vehicle is
substantially shortened. Additionally, a shortened wheel
base in combination with a substantially cantilevered aft
~
CA 02216497 1997-09-24
end may effect the handling characteristics of the vehicle
at higher speeds, or over irregular terrain.
A subsequent design shown in U.S. Patent 4,954,039
issued in 1990 discloses a uniframe rolloff dumpster that
includes a movable frame that pivots relative to a support
plate. This design would be impracticable for light trucks
because of its complicated, expensive design.
Finally in 1991, U.S. Patent 5,000,645 issued
illustrating an apparatus for handling containers that
includes an auxiliary body that is turnable relative to a
chassis wherein a coupler connects the auxiliary body to the
chassis. Although the aft end in this design can rotate to
contact the ground, the '645 design is similar to Groeing in
that it requires the aft end to cantilever substantially
from the chassis thareby limiting the length of the
wheelbase.
Although all of the above cited vehicles provide some
form of a tilting bed that can be lowered substantially to
the ground, they all likewise include a bed structure that
overhangs substantially from the rear of the vehicle frame.
Thus, in each of the above noted designs, the wheelbase
length is somewhat limited.
Accordingly a need remains for a tilting bed design
for use with light trucks where the length of the rear
"overhanging" portion of the bed structure, that extends
4
CA 02216497 1997-09-24
past the vehicle frame is minimized, yet can be lowered
substantially to the ground during the tilting operation.
SUMMARY
One object of the invention is to adapt a tilting bed
apparatus for use on small light trucks to load and unload
payloads.
A second object is to facilitate loading and unloading
payloads on to the tilting bed of a truck from the ground
level.
Another object of the invention is to minimize the
distance the rear portion of a tilting bed must extend
beyond the vehicle frame to facilitate loading and unloading
payloads from the ground.
An additional object is to maximize the wheel base of a
light truck that is configured to receive a tilting bed.
Yet another object is to install a tilting bed to the
frame of a light truck in a way that permits the rear end
portion of the tilting bed to reach the ground when the same
is fully tilted.
A further another object is to, reduce the overall
length of a tilting bed that lowers to the ground during the
tilting operation.
Still another object is to shift the entire tilting bed
rearward during the tilting operation.
CA 02216497 1997-09-24
Another object of the invention is to minimize the
distance the rear portion of a tilting bed must extend
beyond the vehicle frame while maintaining the capacity to
substantially reach the ground during the payload unloading
and loading operation.
The invention is an improved truck mounted payload
loading and unloading apparatus that comprises a tilting bed
disposed over the frame assembly of a vehicle. The tilting
bed includes a forward end, an aft end, and a receiving area
disposed therebetween. The tilting bed is pivotally
supported at a bed pivot joint defined by a portion of the
tilting bed, wherein the tilting bed pivots at the bed pivot
joint about a substantially horizontal bed pivot joint axis.
Importantly, a link member is provided to pivotally
link the tilting bed to the frame assembly. The link
comprises a first end pivotally engaging the frame assembly
at a link pivot joint, a second end pivotally engaging the
tilting bed at the bed pivot joint, and a body portion
extending from the first end to the second end wherein the
link member is pivotable about the link pivot axis.
The tilting bed is pivoted, i.e., tilted by actuators.
Included therein is a first actuator spaced forward of the
link member toward the forward end. The first actuator
being operatively disposed between the frame assembly and
the tilting bed. In this way, the first actuator engages
the frame assembly, extending therefrom to drivingly engage
6
CA 02216497 1997-09-24
the tilting bed. Accordingly, the tilting bed pivots at the
bed pivot joint, elevating the forward end thereof
responsive to actuation of the first actuator.
Additionally, a second actuator is operatively disposed
between the frame assembly and the link member. The second
actuator engages the frame assembly and extends therefrom to
drivingly engage the link member. With this arrangement,
the link member pivots about the link pivot axis, shifting
the bed pivot joint, and likewise the aft end of the tilting
bed, rearward and downward responsive to actuation of the
second actuator. Accordingly, the entire tilting bed shifts
in a rearward direction while simultaneously pivoting so
that the aft end thereof is lowered to the ground.
In accordance with one aspect of the invention, the
actuation of the first and second actuators is synchronized.
More specifically, the first and second actuators are
hydraulically operated by hydraulic fluid, and are
synchronized by a flow divider which metes out the flow of
hydraulic fluid in a predetermined ratio to the first and
second actuator to synchronize their respective motions.
In accordance with another aspect of the invention a
method for loading and unloading payloads from a vehicle
having a frame assembly is disclosed. The method includes
the steps of positioning a tilting bed horizontally over the
frame assembly of the vehicle. The tilting bed comprises a
forward end, an aft end, and a receiving area disposed
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CA 02216497 1997-09-24
= ~
therebetween. The tilting bed being pivotally supported at a
bed pivot joint and capable of pivoting at the bed pivot
joint about a substantially horizontal bed pivot axis.
A link member is provided which includes a first end
pivotally engaging the frame assembly at a link pivot joint,
a second end pivotally engaging the tilting bed at the bed
pivot joint, and a body portion extending from the first end
to the second end. In this way, the link member is
pivotable at the link pivot joint about a link pivot axis
A first actuator is positioned so that it is spaced
forward of the link member toward the forward end.
Accordingly, the first actuator is operatively disposed
between the frame assembly and the tilting bed. Further the
first actuator is engaged with the frame assembly extending
therefrom to drivingly engage the tilting bed. With this
configuration, the tilting bed pivots at the bed pivot
joint, elevating the forward end thereof responsive to
actuation of the first actuator.
Likewise, a second actuator is provided. The second
actuator is operatively disposed between the frame assembly
and the link member. Additionally, the actuator is engaged
with the frame assembly, and extends therefrom to drivingly
engage the link member. Accordingly, the link member pivots
at the link pivot joint, shifting the bed pivot joint, and
likewise the aft end of the tilting bed, rearward and
downward responsive to actuation of the second actuator.
19
CA 02216497 2006-10-04
Further, the first and second actuators are actuated to
elevate the forward end of the tilting bed and shift the aft
end thereof rearward and downward.
With the tilting bed in the tilted position, a payload
can be loaded onto the tilting bed. Finally, the action of
the first and second actuators is reversed to return the tilt-
ing bed to its original horizontal position with the payload
loaded thereon. Unloading the payload is the reverse of the
above noted steps.
The invention thus provides according to an aspect, for a
self-unloading vehicle comprising: a load bed to receive a
demountable load or load deck, movably disposed over a vehicle
chassis, and configured for longitudinal and/or tilting load
or deck movement; the load bed having a pivot mechanism at one
end of the bed, wherein the mechanism comprises a pivot link,
pivotally attached to the load bed at one end, and to the
chassis at the other end, and a link actuator pivotally con-
nected to the pivot link, and operative to displace the load
bed about the chassis, at the opposite end from the pivot
mechanism, a tilt actuator being disposed between the bed and
the chassis frame, and operative to tilt the load bed relative
to the chassis.
The foregoing and other objects, features, and advantages
of this invention will become more readily apparent from the
following detailed description of a preferred embodiment which
proceeds with reference to the accompanying drawings, wherein
the preferred embodiment of the invention is shown and
described, simply by way of illustration of the best mode
contemplated of carrying out the invention. As will be
realized, the invention is capable of other and different
embodiments, and its several details are capable of modifi-
cations in various obvious respects, all without departing
9
CA 02216497 2006-10-04
from the invention. Accordingly, the drawings and description
are to be regarded as illustrative in nature, and not as
restrictive.
9a
CA 02216497 1997-09-24
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation view showing a prior art vehicle
having a tilting bed that pivots about a bed pivot joint
disposed substantially at the aftmost point on the frame
assembly.
FIGS. 2 through 5 are fragmentary side elevation views
showing the synchronized operation of actuators and the
resulting simultaneous movement of a link member and tilting
bed in the tilting sequence of the tilting bed; the sequence
begins with the tilting bed in the horizontal stowed
position shown in FIG. 2, continuing with intermediate
tilted positions shown in FIGS. 3 and 4, and finally a full
tilted position as shown in FIG. 5 wherein the aft end of
the tilting bed is lowered substantially to the ground.
FIG. 6 is a rear perspective view showing a tilting bed
in the tilted position, wherein the payload conveyance
mechanism is in the aft release position, and the payload
support structure thereof is separated and not illustrated.
FIG. 7 is a fragmentary view looking down on the
forwardmost portion of the drive mechanism, wherein dual
spaced apart drive chains are being driven by hydraulic
motors.
1t~
CA 02216497 1997-09-24
FIG. 8 is a fragmentary side elevation view of a
link member connecting the tilting bed to the frame
assembly, wherein the tilting bed in the tilted position.
FIG. 9 is a fragmentary perspective view showing the
carriage portion of a payload conveyance mechanism.
FIG. 10 is a simplified fragmentary isometric view
showing the drive mechanism of a payload conveyance
mechanism.
FIG. 11 is a fragmentary perspective view of a link
member connected to spaced apart hydraulic cylinders that
extend from the frame assembly, the centrally located
phantom lines showing a single hydraulic cylinder driving a
link member. -
FIG. 12 is a rear side perspective view showing a
tilting bed in the fully tilted position with a single
counter link member/ hydraulic cylinder forwardly disposed,
wherein the payload conveyance mechanism is unloading a
payload support structure.
\1
CA 02216497 1997-09-24
FIG. 13 is a schematic diagram illustrating a hydraulic
control circuit/system in accordance with the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
FIGS. 2 through 13 illustrate a truck mounted payload
loading and unloading apparatus 20 constructed in accordance
with the present invention. In contrast, FIG. 1 shows a
typical arrangement for vehicles having a tilting bed
constructed in accordance with the prior art where the rear
bed pivot joint is stationary, and thus does not move
relative to the vehicle frame. Indicated generally at 30 is
a truck of the type having a frame assembly 32 supported by
a plurality of wheels including a pair of forwardmost wheels
34 and a pair of aftmost wheels 36. Mounted atop the truck
30, over the frame assembly 32, is a tilting bed 38. As
will be discussed more fully below, the tilting bed 38 is
tiltable from a horizontal position to an upright tilted
position for unloading and loading payloads.
The tilting bed 38 comprises a forward end 40 disposed
adjacent the passenger cab 42; an aft end 44 that defines
the most rearward portion of the tilting bed 38; and a
receiving area 45 disposed therebetween. To enable pivoting
thereof relative to the frame assembly 32, the tilting bed
01
CA 02216497 1997-09-24
{
38 comprises a bed pivot joint 46 disposed between the
forward end 40 and the aft end 44. The bed pivot joint 46
is defined by a portion of the tilting bed 38: the bed pivot
joint 46 defines the connection point between the tilting
bed 38 and the link member 56. As can be seen, that portion
of the tiltina bed 38 that extends rearward from the bed
pivot joint 46 to the aft end 44 is cantilevered from the
bed pivot joint 46. Further, the tilting bed 38 is
pivotally supported at the bed pivot joint 46 and is
pivotable at the bed pivot joint 46 about a substantially
horizontal bed pivot axis 48 as best seen in FIGS. 8 and 11.
Supported by the tilting bed 38, is a payload
conveyance mechanism 50. As will be more fully described in
the following, the payload conveyance mechanism 50 includes
a payload support structure 52 which is provided to support
and secure a payload 54 during the transportation thereof.
The payload support structure 52 is a platform that can be
removed from the tilting bed 38 for ease of unloading and
loading payloads 54 thereon. A typical payload 54 could
comprise a container as illustrated (by phantom lines) in
FIGS. 2 through S.
During transportation of the payload 54, the payload
support structure 52 is disposed over the tilting bed 38,
adjacent the receiving area 45 and is supported thereby.
Further, as will be described more fully below, the payload
conveyance mechanism 50 includes a combination of working
13
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CA 02216497 1997-09-24
parts, supported by the tilting bed 38, that cooperate to
enable the user to transfer the payload support structure 52
onto and off the tilting bed 38.
Importantly, a link member 56 is provided to pivotally
connect the tilting bed 38 to the frame assembly 32. A link
member 56 so provided enables the entire tilting bed 38 to
shift in a rearward direction as will as pivot, i.e. tilt.
In this way, the aft end 44 of the tilting bed 38 is capable
of reaching the ground during the tilting operation, yet
shift close to the frame assembly 32 when the tilting bed 38
is in the horizontal, untilted position.
It should be noted that FIGS. 2 through 5 are provided
primarily to illustrate the shifting and tilting action of a
tilting bed 38 in accordance with the present invention;
those FIGS., however, do not show the preferred embodiment
of the construction of a link member 56. The construction
of a link member 56 in accordance with the preferred
embodiment is illustrated in FIGS. 6, 8 and 11. As will be
seen in the following, the link member 56 is comprised of a
combination of tubular steel members coupled together by
welding the same to form one unitary link member 56 arranged
to fit within the frame assembly 32.
As best seen in FIGS. 8 and 11 the link member 56
includes a first end 58, an opposing second end 62, and a
body portion 64. The first end 58 pivotally engages the
frame assembly 32 at a link pivot joint 60; the second end
,y
CA 02216497 1997-09-24
62 pivotally engages the tilting bed 38 at the bed pivot
joint 46; and the body portion 64 extends therebetween from
the first end 58 to the second end 62. Accordingly, the
link member 56 is pivotable at the link pivot joint 60 which
is defined by the pivotal connection of the link member 56
to the frame assembly 32.
To actuate the tilting motion of the tilting bed 38, a
pair of longitudinally spaced-apart actuators are provided.
Included therein is a first actuator 66 spaced forward of
the link member 56, toward the forward end 40 of the tilting
bed 38. The first actuator 66 is operatively disposed
between the frame assembly 32 and the tilting bed 38. More
specifically, the first actuator 66 engages the frame
assembly 32, extending therefrom to drivingly engage the
tilting bed 38, wherein the tilting bed 38 pivots at the bed
pivot joint 46, about a bed pivot axis 48, elevating the
forward end 40-responsive to actuation of the first actuator
66.
Similarly, a second actuator 68 is operatively disposed
between the frame assembly 32 and the link member 56. The
second actuator engages the frame assembly 32 forward of the
link pivot joint 60 and extends therefrom to drivingly
engage the link member 56. In this way, the link member 56
pivots at the link pivot joint 60, about a link pivot axis
99, finally shifting the bed pivot joint 46 rearward and
downward responsive to actuation of the second actuator 68.
1C___1
CA 02216497 1997-09-24
Likewise the aft end 44 of the tilting bed 38 shifts
rearward and downward thereby bringing the same closer to
the ground to facilitate loading and unloading payloads. it
should be appreciated that in the preferred embodiment, the
first and second actuators 66-68 operate simultaneously, and
are synchronized to operate at a predetermined but different
rate, so that the tilting bed 38 moves and shifts in a one
continuous motion from a horizontal position to a fully
tilted position as seen in FIGS. 2 through 5.
Considering now in more detail the structure of the
components from which the payload loading and unloading
apparatus 20 is assembled, FIGS. 1 through 6 illustrate a
truck 30 having frame assembly 32. The primary structural
components of the frame assembly 32 are a pair of parallel,
spaced apart frame rails 70-71 (left side and right side)
that run longitudinally, substantially the length of the
truck 30. The-frame rails 70-71 provide support, directly
or indirectly, for most of the components of the payload
loading and unloading apparatus 20.
In addition, for the purposes of this specification, it
should be appreciated that the frame assembly 32 includes a
plurality of mounting plates fixed thereto for mounting
various components of the payload loading and unloading
apparatus 20 to the frame rails 70-71. Included therein is
a front actuator mounting plate 72 which secures one of the
two hydraulic cylinders 74-75 that comprise the first
lL
CA 02216497 1997-09-24
actuator 66. The actuator mounting plate 72 is located on
th-e left frame rail 70 for securing hydraulic cylinder 74.
A matching "mirror image" mounting plate is similarly
located on the right frame rail 71 (not illustrated) for
securing hydraulic cylinder 75 to frame rail 71 as shown in
FIG. 6. Typically, the mounting plates are constructed of
ordinary plate steel arranged to receive and secure a
hydraulic cylinder. The mounting plates are fixed to the
frame rails 70-71 by welds, bolts or by some other suitable
means of fastening.
Turning now to FIG. 6, a tilting bed 38 is illustrated
in the tilted position. The tilting bed 38, in the tilted
position, is supported substantially at the forward end 40
by the first actuator 66. In the preferred embodiment the
first actuator 66 comprises two spaced apart double acting
hydraulic cylinders 74-75. The operation and control of the
hydraulic cylinders 74-75 will later be more fully
described. Although hydraulic cylinders are employed in the
present invention, other equipment could be adequately
substituted therefor including pneumatically driven
cylinders.
The tilting bed 38 is constructed of common structural
components welded together to form a generally planar,
rectangular frame. The sides thereof comprise a pair of
spaced apart, parallel side rails 76-77. Typically the side
rails 76-77 are constructed from steel "I" sections with the
1--I
-------------- --------
CA 02216497 1997-09-24
= 4
flanges extending horizontally. However, channel sections
could be substituted without any significant change in
performance or design.
The extremities, forward end 40 and aft end 44, of the
tilting bed 38 comprise "built-up" structural components
that extend transversely and horizontally from one side rail
76 to the opposite side rail 77. At the forward end 40 is
the forward end member 84, and at the aft end 44 is the aft
end member 86. The forward end member 84 is constructed
from plate steel oriented normal to the longitudinal
direction of the side rails 76-77, with a thin steel bar
welded continuously to the edge thereof forming a continuous
flange 88. The forward end member 84 is attached to the
ends of the side rails by butt welding the same to the plate
steel. Additionally, the forward end member 84 is of
sufficient width to extend horizontally approximately two to
three inches past each side rail 76-77. In this way, a slot
90 is formed between the respective side rail and the
flange. A slot so formed provides a connection point for
the respective hydraulic cylinder 74-75 or the piston
thereof. Specifically, holes are provided through the
flange 88 and the respective side rail 76-77, so that the
piston 89 of a hydraulic cylinder can be received
therebetween and secured with a bolt (not illustrated.)
Similarly, the aft end member 86 is "built-up" from
plate steel and extends from the one side rail 76 to the
18
CA 02216497 1997-09-24
opposite side rail 77. The plate steel is oriented normal
to the longitudinal direction of the side rails 76-77, and
like the forward end member 84, the aft end member 86 is
butt welded to the ends of the respective side rail. Like
the forward end member 84, the aft end member 86 includes
thin bar steel welded to the plate steel edge to form a
flange 92. In the aft end member 86, however, no portion
thereof extends past the side rails 76-66. It should be
noted that the side rails 76-77 and the end members 84-86
are the primary "frame" components of the tilting bed 38.
Moreover, the construction of each end member 84-86 and
the attachment thereof to the side rails as noted above is
somewhat arbitrary and could therefore be accomplished in a
number of different ways without changing the performance or
operation of the invention. For example, the end members
84-86 could be constructed of standard structural shapes,
such as channel sections, with slight modification to
produce equally desirable results.
In addition to the above, the tilting bed 38 comprises
a plurality of bed cross members 78, 80 and 82. The cross
members 78, 80 and 82 are made from square or rectangular
steel tube, and extend transversely from one side rail to
the opposing side rail. They are attached to the bottom of
the respective side rails 76-77 by welding the same together
in a conventional manner. The cross members 78, 80 and 82
are provided primarily to rigidify the tilting bed 38 and to
. \ck
CA 02216497 1997-09-24
provide support for hydraulic hoses (not illustrated.) As
will be more fully explained below, the area defined by the
above noted tilting bed construction, between the aft end 44
and the forward end 40 is the receiving area 45, where a
payload support structure 52 is located and supported during
transport of the payload that is loaded atop the payload
support structure 52.
Attention is now directed to FIGS. 2 through 6, and 8
wherein a link member 56 is illustrated. The link member 56
is disposed between the tilting bed 38 and the frame
assembly 32. The link member 56 is the component that
"pivotally links" the tilting bed 38 to the frame assembly
32 in a way that enables the tilting bed 38 to shift
rearward as well as tilt. As previously noted, FIGS. 2
through 5 are provided primarily to illustrate the shifting
and tilting action of a tilting bed 38, and do not show the
preferred embodiment of the construction of a link member
56. The preferred embodiment/construction of a link member
56 is illustrated in FIGS. 6, 8 and 11.
In the preferred embodiment, the link member 56 is
constructed from a combination of steel components welded
together to form a rigid, unitary structure adapted to fit
between the frame rails 70-71, extending horizontally from
one frame rail 70 to the opposing frame rail 71. Broadly
stated, the link member 56 comprises a first end 58 disposed
adjacent the frame rails 70-71 of frame assembly 32, a
CA 02216497 1997-09-24
= 4
second end 62 disposed adjacent the side rails 76-77 of
tilting bed 38, and a body portion 64 extending between the
first end 58 and the second end 62. The first end 58 is
defined by that portion of the link member 56 that provides
means for pivotally connecting the link member 56 to the
frame assembly 32. Likewise, the second end 62 is that
portion of the link member 56 that provides means for
connecting the link member 56 to the tilting bed 38. As
will be more fully discussed in the following, the preferred
means for connecting the link member 56 at its end to the
tilting bed 38 and to the frame assembly 32 includes a
plurality of pivot rods disposed through bores provided in
the respective first end 58 or second end 62.
To enable connection of the link member 56 to the frame
assembly 32, the frame assembly 32 includes a pair of rear
mounting plates 94 (FIGS. 2-5) and 96 (FIGS. 6, 8, 11 and
12). The rear-mounting plates are similar in construction
wherein each is the "mirror image" of the other. Rear
mounting plate 94 is fixed to the rear of frame rail 70, and
rear mounting plate 96 is fixed to the rear of frame rail
71. The rear mounting plates 94-96 can be fastened to the
frame rails in any conventional manner including bolts,
welds or a combination thereof. As will be described below,
the first end 58 of the link member 56 fits between the
frame rails 70-71 and is pivotally attached to the mounting
plates 94-96.
,3t\
CA 02216497 1997-09-24
To enable pivotal attachment of the link member 56 to
the rear mounting plates 94-96, a horizontally disposed
pivot rod 98 extends from one rear mounting plate 94,
through the first end 58 of link member 56, and on to the
opposing rear mounting plate 96. Accordingly, the pivot rod
98 defines a link pivot axis 99 about which link member 56
pivots. The pivot rod 98 is pivotally supported at its ends
by a pair of pivot sleeves (only one pivot sleeve 100 is
illustrated - see FIG. 11.) For example, in the preferred
.embodiment, a sleeve bore 101 is provided through pivot
sleeve 100 and is so provided to receive the pivot rod 98
therethrough, and support the same along the link pivot axis
99.
For this purpose, the pivot sleeve 100 is welded to
rear mounting plate 96 wherein a coaxially disposed plate
bore 102 is similarly provided through mounting plate 96.
In this way, pivot rod 98 extends along the link pivot axis
99 through sleeve bore 101, and through bore 102. It should
be noted that a gusset plate 103 is welded between the pivot
sleeve 100 and the rear mounting plate 96 for added
strength. Additionally, the pivot rod 98 extends a short
distance outside of rear mounting plate 96 so that a common
retaining device such as a "C" clip or a cotter pin (not
illustrated) can be properly installed on the pivot rod 98
to prevent the same from sliding back through pivot sleeve
100.
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CA 02216497 1997-09-24
It should be appreciated that the opposing end of pivot
rod 98 (not illustrated) is supported in exactly the same
way by a corresponding pivot sleeve attached to rear
mounting plate 94; thus the arrangement of the left side is
a mirror image of the right side. In addition, in the
preferred embodiment, the pivot rod 98 is centrally braced
by a pivot rod brace 97. The pivot rod brace 97 is provided
to prevent any possible deformation of the pivot rod 98 that
might take place due to extreme loads imparted thereon by
the link member 56. The pivot rod brace 97 is simply a
steel tubular sleeve, sized to receive the pivot rod 98,
attached to a bracket that is welded to a frame cross member
95.
Considered below in more detail, are the components
from which a link member 56 is constructed. Included
therein are a plurality of steel tubular members arranged
and welded together to form a substantially planar, rigid,
unitary structure that defines the greater portion of link
member 56. Specifically, two transversely disposed, spaced
apart, parallel steel tubular members 104-105 are welded at
the ends thereof to two opposing pivot members 108-109. As
best seen in FIG. 11, pivot members 108-109 are spaced,
wherein pivot member 108 is disposed adjacent rear mounting
plate 94, and pivot member 109 is disposed adjacent rear
mounting plate 96. The pivot members 108-109 are aligned in
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CA 02216497 1997-09-24
= 4
a direction substantially parallel to the longitudinal
direction of the truck 30.
Importantly, respective end portions of pivot members
108-109 define the first end 58 and the second end 62 of
link member 56. In particular, pivot member 108 includes a
frame end 110 disposed adjacent the frame assembly 32, and a
bed end 111 disposed adjacent the tilting bed 38.
Similarly, pivot member 109 includes a frame end 112
disposed adjacent the frame assembly 32, and a bed end 113
disposed adjacent the tilting bed 38. Together, frame end
110 in combination with frame end 112 represent the first
end of link member 56. Likewise, bed end 111 together with
bed end 113 represent the second end of link member 56.
In light of the above, it should be understood that
the end portions of the pivot members 108-109 are defined by
that portion of the pivot member that provides means for
pivotally connecting the same to an adjacent supporting
component, namely a pivot rod. Accordingly, as will be more
fully discussed below, the above noted end portions are
defined substantially by the portion of steel tube that
includes bores therethrough for receiving a pivot rod.
To enable pivotal support of the link member 56, pivot
rod 98 extends through bore 114 provided in frame end 110,
and through bore 115 provided in frame end 112. As
previously noted, pivot rod 98 is rotatably supported at the
ends thereof by pivot sleeves, including pivot sleeve 100,
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CA 02216497 1997-09-24
that are fixed to respective mounting plates 94-96. In this
way, the link member is pivotally connected to the frame
assembly 32 by way of rear mounting plates 94-96.
Accordingly, the link pivot joint 60 is defined by the
components that facilitate the relative pivotal movement of
the link member 56 to the frame assembly 32 including pivot
sleeves (only pivot sleeve 100 is illustrated), pivot rod
98, and the first end 58 of link member 56.
Similarly, to enable pivotal attachment of the tilting
bed 38 to the second end 62 of link member 56, a pair of
mounting brackets 122-124 are provided. Mounting bracket
122 is fixed, i.e., welded to the under surface of side rail
76, and, likewise mounting bracket 124 is fixed to the under
surface of side rail 77. Further, each mounting bracket
122-124 is disposed adjacent cross member 82 so that a
portion of each mounting bracket 122-124 can be welded to
cross member 82 for added strength and support. The
mounting brackets 122-124 are similarly constructed, each
being a mirror image of the other. The mounting brackets
122-124 are disposed along the side rails 76-77, located to
establish the location the bed pivot joint 46 relative to
the tilting bed 38.
In addition, each mounting bracket 122-124 comprises a
pair of spaced downwardly projecting tabs constructed from
welded plate steel, and arranged to form a slot. Slot 128
is formed on mounting bracket 122, and slot 129 is formed on
as
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CA 02216497 1997-09-24
mounting bracket 124. Slots so provided are disposed to
receive the bed ends 111-113 of pivot members 108-109
thereby pivotally connecting the link member 56 to the
tilting bed 38.
Connection of the second end 62 of link member 56 to
the mounting brackets 122-124 is facilitated by a pair of
pivot rods 126-127. Pivot rods 126-127 define the bed pivot
axis 48 and are disposed through the second end 62 of link
member 56 as well as through the mounting brackets 122-124.
Specifically, each bed end 111-113 of each pivot member 108-
109 is formed to include a horizontally disposed bore: bed
end 111 includes a bore (not illustrated), and bed end 113
includes bore 117. These bores are so provided to coaxially
align with bore 116 (shown in phantom lines FIG. 11) and
with bore 119 found 'Ln the mounting brackets 122-124. In
this way, pivot rods 126-127 can be employed through the
bores thereby pivotally connecting the link member 56 to the
tilting bed 38. Additionally, the pivot rods 126-127 are of
sufficient length so that a retaining device such as a "c"
clip or the like (not illustrated) can be employed to
maintain the pivot rods in proper position and thus prevent
the same from sliding out of position.
As will be more fully discussed below, pivoting of the
link member 56 is controlled and induced by an actuator
connected thereto. In the preset invention, the actuator is
a pair of hydraulically operated double acting cylinders
2k,
CA 02216497 1997-09-24
that extend from the frame assembly 32 to the link member
56. Further, the cylinders 134-135 include respectively
pistons 137-138 that are connected to the body portion 64 of
the link member 56, wherein the piston brackets 144-145
facilitate the connection. Specifically, in the present
invention, the piston brackets 144-145 are simply a pair of
triangular shaped steel plates spaced to form a slot that
can receive the piston of a hydraulic cylinder. The piston
brackets 144-145 are welded to member pivot members 108-109
and include a bore through which a pin (not illustrated) is
provided to secure the pistons 137-138 to the piston
brackets 144-145.
Considering now in more detail the actuators that
control the tilting motion of the tilting bed 38, actuators
56 and 68 are provided. As previously noted, in the
preferred embodiment, the first and second actuators 66-68
comprise a plurality of double acting hydraulically operated
cylinders. Each cylinder in the present invention includes
a cylinder bore of 3 inches, and a piston size of 1.75
inches. Further, the cylinders that tilt the tilting bed 38
have a travel length of 3 feet, whereas the cylinders that
pivot the link member 56 have a travel length of 1 foot.
Turning now to FIGS. 1 through 6 and 11, extending from
the forward portion of the frame assembly 32 is hydraulic
cylinder 74 on the left side of the frame assembly 32:
hydraulic cylinder 74 extends from the left frame rail 70 to
X-1-
CA 02216497 1997-09-24
the tilting bed 38; similarly hydraulic cylinder 75 extends
from the right frame rail 71 to the tilting bed 38. More
specifically, each hydraulic cylinder 74-75 includes a
piston 130-131 that is movably received within the cylinder.
Each piston 130-131 extends from a hydraulic cylinder for
connection to the tilting bed 38. The connection between
the hydraulic cylinders 74-75 and the respective frame rail
is facilitated by a actuator mounting plate: actuator
mounting plate 72 for hydraulic cylinder 74 as seen in FIGS.
2 through 5. The actuator mounting plate 72 is fabricated
from plate steel, arranged to form a connection seat (not
illustrated) of a design commonly used for receiving a
hydraulic cylinder. Similarly, a "mirror image" mounting
plate (not illustrated) is employed to attach hydraulic
cylinder 75 the frame assembly 32.
As previously noted, the pistons 130-131 of hydraulic
cylinders 74-75 extend to a respective slot defined by the
forward end member 84 of the tilting bed 38. For example,
piston 131 of hydraulic cylinder 75 extends to slot 90 as
seen in FIG. 6. Similarly, a slot (not illustrated) is
provided for the connection of piston 130 to the tilting bed
38. The slots are provided for receiving and pivotally
connecting the hydraulic cylinder to the tilting bed 38.
In operation, when the tilting bed 38 is in the
horizontal position (FIG. 2), the pistons 130-131 of the
hydraulic cylinders 74-75 are fully retracted. In this way,
ZZ8
CA 02216497 1997-09-24
actuation of the same causes pistons 130-131 to extend and
thereby raise the forward end 40 of the tilting bed 38
thereby urging the tilting bed 38 to pivot at the bed pivot
joint 46 about the bed pivot axis 48.
Extending from the rear portion of the frame assembly
32 to the link member 56 is the second actuator 68 which
comprises a pair of double acting hydraulic cylinders 134-
135. In the preferred embodiment, as best seen in FIG. 11,
the hydraulic cylinders 134-135 are disposed between the
frame rails 70-71. Accordingly, as noted above, the
arrangement of hydraulic cylinders as illustrated in FIGS. 2
through 5 are provided only to generally show the pivoting
action of the link member 56, and to generally show the
tilting motion of the tilting bed 38.
Like the hydraulic cylinders of the first actuator 66,
the hydraulic cylinders 134-135 include movable pistons 137-
138. In the preferred embodiment, the hydraulic cylinders
134-135 are supported from the frame assembly 32 from a
tubular cross member 95 that extends transversely from
mounting plate 94, as illustrated in FIG. 11, to mounting
plate 96 (not shown in FIG. 11). The cross member 95 is
attached to the mounting plates, adjacent to and under the
frame rails, by welding or bolting the same together.
Further, it should be appreciated that the connection of the
hydraulic cylinders 74-75 and 134-135 to their respective
connection points, in the present invention, is done in a
XA,
- ------------------ ---
CA 02216497 1997-09-24
conventionally straightforward manner employing well known
details found in the construction of such hydraulically
actuated mechanisms.
For example, hydraulic cylinders 134-135 are each
pivotally connected to a separate cylinder bracket mounted
and welded to cross member 140. Cylinder 134 is connected to
cylinder bracket 141, and cylinder 135 is connected to a
similarly disposed, spaced apart cylinder bracket (not
illustrated). Cylinder bracket 141 is mounted to cross
member 140 by welding the same in a conventional manner.
Cylinder 134 extends therefrom to the body 64 of link member
56. Specifically, the pistons 137-138 of hydraulic
cylinders 134-135 are pivotally connected to piston brackets
144-145 which are constructed from spaced apart steel plates
as previously noted. The pistons 137-138 are respectively
connected thereto in a conventional manner where a pin
pivotally connects the piston to the central portion of the
bracket, between the plates. In this way the hydraulic
cylinders 134-135 can be actuated to pivot link member 56
about the link pivot axis 99.
In operation, when the tilting bed 38 is in the
horizontal position (FIG. 2), the pistons 137-138 of the
hydraulic cylinders 134-135 are fully retracted. In this
way, actuation of the same cause the pistons 137-138 to
extend and thereby pivot the link member 56 about the link
pivot axis 99 which, in consequence, causes the tilting bed
CA 02216497 1997-09-24
38 to shift in a rearward direction. As will be discussed
more fully below, the flow of hydraulic fluid to the
hydraulic cylinders 74-75 and 134-135 is meted, i.e.,
divided and split in a predetermined ratio so that the
operation of all hydraulic cylinders occurs simultaneously
to produce a synchronized smooth continuous tilting action
of the tilting bed 38.
Additionally, it should be appreciated that a single
actuator 142, as illustrated by phantom lines in FIG. 11,
could be employed in place of the preferred embodiment
configuration of dual cylinders 134-135. If a single
actuator 142 were employed, the connections to the cross
member 140 and to the body portion 64 of link member 56
would be of the same construction as those of the preferred
embodiment.
Similarly, a single actuator 146, as illustrated in
FIG. 12, could-be employed in place of cylinders 74-75 which
comprises the first actuator 66. Like single actuator 142,
the connections to the tilting bed 38, and to the frame
assembly 32 would be accomplished in a conventional manner
(not illustrated).
Turning now to FIGS. 6 through 10 and 12, a payload
conveyance mechanism 50 constructed in accordance with the
present invention is illustrated. The payload conveyance
mechanism 50 is provided for loading and unloading payloads
54 from the tilting bed 38. The payload conveyance
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CA 02216497 1997-09-24
mechanism 50 comprises a payload support structure 52 for
receiving a payload 54, and a drive mechanism 152 mounted to
the tilting bed 38 for transferring the payload support
structure 52 onto and off the tilting bed 38. Further, the
drive mechanism 152 comprises a combination of both moving
and stationary parts that cooperate to so transfer the
payload support structure 52.
Considering now in more detail, a drive mechanism 152,
as best seen in FIGS. 7, 9 and 10, comprises a carriage 154
that is movably supported within, and between the side rails
76-77 of the tilting bed 38. As will be seen below, the
carriage 154 is reciprocally movable, by a driven chain,
along the side rails 76-77 for moving the payload support
structure 52 onto and off the tilting bed 38. The carriage
154 comprises a pair of horizontally disposed, parallel,
abutting steel tubes welded together to form a carriage
frame 155. Welded to one end thereof is an end plate 156
provided for rotatably securing a pair of horizontally
spaced trolley wheels: see FIG. 9 where only one trolley
wheel 158 is illustrated. The opposing end of the carriage
154 is a mirror image and is shown in FIG. 10. Similarly,
an end plate 157 is welded to the carriage frame 155 to
rotatably secure a pair of horizontally spaced trolley
wheels: only one trolley wheel 159 is illustrated (FIG. 10).
Thus, the carriage 154 is supported at its ends by a
plurality of trolley wheels that are rotatably attached
J~
CA 02216497 1997-09-24
thereto via end plates 156-157. Moreover, the opposing
pairs of trolley wheels are so disposed and spaced to
support the carriage 154 in a stable, efficient manner. As
noted above the trolley wheels are received between the
flanges of the respective side rails 76-77. To illustrate,
FIG. 9 shows a wheel 158 rotatably mounted to carriage 154,
at one end thereof, for rotating engagement with side rail
77. Wheel 158, of the two wheel pair, is so disposed so
that it can ride between the flanges of the side rail 77.
Similarly, at the opposing end of the carriage 154 is wheel
159 rotatably mounted to end plate 157, for rotating
engagement with side rail 76 (not illustrated in FIG. 10).
Each pair of the above noted trolley wheels are attached to
the opposing end plates 156-157 of the carriage 154 in a
conventional manner, i.e., by bolts that are secured to the
end plates.
Disposed in the center of the carriage 154 is a hook
160. The hook 160 is fixed to carriage frame 155, by welds,
for releasable engagement with a catch 162 disposed on the
forward end of the payload support structure 52 as seen in
FIG. 9. In this way, the payload support structure 52 moves
responsive to movement of the carriage 154. It should be
appreciated that the payload support structure 52 can be
disengaged from the hook 160 by tilting the tilting bed 38
upward and simultaneously moving the carriage 154 to the aft
end thereof. In this way, the payload support structure 52
33
CA 02216497 1997-09-24
can be completely removed from the tilting bed as shown in
38 FIG. 6. It should be noted that the payload support
structure 52 is simply a form of a skid built to receive
payloads 54. In the preferred embodiment, the payload
support structure 52 is a simple frame having a rigid
surface disposed underneath to slide upon and along the side
rails 76-77 responsive to movement of the carriage 154.
Also, as illustrated in FIG 12, the preferred embodiment of
the payload support structure 52 includes four legs, one leg
161 at each corner. Further, the aft legs include wheels 163
which eases the removal of the payload support structure
from the tilting bed 38. Moreover, it should be understood
that the payload support structure 52 could be arranged and
built in many different configurations depending on the
needs of the user.
Turning now to FIG. 10, a fragmentary isometric view of
a drive mechanism is shown in accordance with the present
invention. Because the drive mechanism 152 is substantially
symmetrical about the longitudinal axis of the truck 30,
only the left side thereof is illustrated, i.e., the right
side is a mirror image of the left side. Included therein
is a drive chain 164 that is coupled to the carriage 154 via
a chain connector 166. As illustrated, a lug 167 extends
from the carriage 154 to receive the chain connector 166.
It should be noted that the chain connector 166 is a well
3'~
CA 02216497 1997-09-24
known and available component employed for connecting a
chain to another part.
The left drive chain 164 is of a sufficient length to
extend around a plurality of sprockets, including a chain
drive sprocket, wherein it finally is guided back to the
carriage 154 and connected thereto via another chain
connector 166 which, at this end of the drive chain 164, is
attached directly to the carriage frame 155. With this
configuration, the drive chain 164 can impart forces to the
carriage 154 to move it in either a forward direction 168 to
transfer a payload support structure 52 onto the tilting bed
38, or an aft direction 169 to transfer a payload support
structure 52 off the tilting bed 38.
To so impart forces, the drive chain 164 is driven by a
train of sprockets and an endless chain that initially are
energized by a hydraulically powered, reversible transport
motor 170. As-will be more fully described below, the
transport motor 170 is part of a hydraulically controlled
system that also controls the actuators. The transport
motor 170 drives a main drive sprocket 172 which is keyed to
motor shaft 173. Motor shaft 173 extends directly from the
transport motor 170 to transfer forces generated thereby.
An endless drive chain 174 is guided around the main drive
sprocket 172, and similarly around a spaced apart driven
sprocket 176. Driven sprocket 176 is keyed to a driven
shaft 177 which in-turn transfers forces, initially
CA 02216497 1997-09-24
generated by the transport motor 170, to the drive chain
164.
More specifically, driven shaft 177 extends from the
driven sprocket 176 outward to drive chain 164 and is
coupled thereto by a keyed drive sprocket 178. Accordingly,
upon energizing the transport motor 170, forces generated
thereby are transferred via drive chain 174 to the driven
shaft 177, which in-turn transfers the same to the drive
sprocket 178 and thereby to drive chain 164 thus urging
carriage 154 along the side rails of tilting bed 38.
In order to guide and properly route the drive chain
164 from the carriage 154, around the drive sprocket 178 and
then back to the carriage 154, a plurality of like idler
sprockets, which are keyed to like idler shafts, are
provided. In particular, four like idler sprockets 180 are
keyed to four like idler shafts 182 to form four idler
assemblies 184; 185, 186 and 187. The same are disposed
generally as illustrated in FIG. 10. Idler assembly 184 is
provided to redirect drive chain 164 from a horizontal
direction downward to drive sprocket 178. Idler assemblies
185 and 186 are adjacently disposed and provided to raise
the drive chain 164 and guide the same to idler assembly
187. Finally, idler assembly 187 is provided to redirect
the drive chain 180 degrees, around an idler sprocket 180
and from there back to the carriage 154.
- - ---------- -
CA 02216497 1997-09-24
As earlier noted, the drive mechanism 152 is
substantially symmetrical about the longitudinal axis of the
truck 30, and that the right side is a mirror image of the
left side. Accordingly, each sprocket and drive chain on
the left side has a duplicate corresponding sprocket and
drive chain on the right side. Further, except for the
shafts that extend directly from the transport motors, each
shaft having a sprocket keyed thereto, extends horizontally
from the left side (side rail 76) of the tilting bed 38 to
the right side (side rail 77) thereof. Included therein is
the drive shaft 177 and idler assemblies 184 through 187.
In this way, each shaft that is provided to support a
sprocket on one end, also provides support for the
corresponding sprocket on the other end of the shaft.
Importantly, this arrangement synchronizes the chains
and sprockets of the opposing left side and right side.
Specifically, the tension forces and displacements developed
in the corresponding left side and right side chains are
equal and simultaneous and thereby prevent any tendency for
racking or binding of the carriage 154 as it travels along
the side rails 76-77. Further, it should be noted that in
the present invention, only two sizes of sprockets are
employed. As best seen in FIG. 10 sprockets 180 (four
each), 178, and 172 are of a sufficient size to have 9
teeth. In contrast, driven sprocket 176 is sized to
371-
- --- - --- ------
CA 02216497 1997-09-24
include 19 teeth. Accordingly shaft 177 turns at .47 times
the RPM of the motor shaft.
Directing attention to FIG. 7, a typical bearing block
175 is illustrated supporting idler assembly 184 on the
right side thereof. As can be seen, the shaft of each idler
assembly is supported by a pair of spaced apart bearing
blocks. Generally, the bearing blocks employed in the
preferred embodiment are of conventional construction and
readily available. The bearing blocks provide ball bearing
support wherein the shafts are permitted to freely rotate,
with set screws provided on the bearing blocks to prevent
translation of the shaft. Moreover, each bearing block is
attached to a portion or component of the tilting bed 38.
For example, idler assmbly 184 is fixed to forward end
member 84 by bolting the same.
Beyond this, it should be noted that the transport
motors 170 and-171 are supported from a pair of spaced motor
brackets 197 that are fixed to a support frame 196.
Accordingly, the support frame is disposed between the side
rails 76-77, and is attached thereto. The support frame can
be attached to the side rails by any conventional method
including bolts or welds. The design of the motor brackets
197, and the support frame 196 is simple and straight
forward, and could be modified in a number of equally
acceptable ways. Because understanding of this invention is
not dependent upon nor is it limited to such design details,
-3 S
CA 02216497 1997-09-24
which are within the capability of everyday mechanical
skill, the present disclosure has not included such details.
It should also be noted that through
Turning now to FIG. 13, a schematic diagram of a
hydraulic control system, hereinafter referred to a system
200, in accordance with the present invention is
illustrated. The system 200 is provided to control the flow
of hydraulic fluid to the various hydraulically controlled
components as described below. In the preferred embodiment,
the system 200 includes two primary actuators: first
actuator 66 and second actuator 68. First actuator 66
comprises two hydraulically operated double-acting cylinders
74-75. Similarly, the second actuator 68 comprises two
hydraulically operated double-acting cylinders 134-135.
The system also comprises a fluid reservoir 202, an
electric clutch hydraulic pump 204 which supplies all the
hydraulic fluid to the system 200, and two main control
valves 206 and 208. The pump 204 being mounted to the
vehicle engine (not illustrated), wherein activation thereof
is by an electric clutch controlled from a switch mounted in
the cab of the truck (not illustrated).
The main control valves 206-208 are 3 position, 4 way
tandem center (electric solenoid) control valves. As will
be discussed below, main control valve 206 controls the flow
of hydraulic fluid to the actuators 66-68, and main control
valve 208 controls the hydraulic fluid to the transport
3~
CA 02216497 1997-09-24
motors 170-171 of the drive mechanism 152. The transport
motors 170-171 are Bi-rotational and hydraulically operated.
Referring now to the main control valve 206, 3
position, 4 way tandem center (electric solenoid) control
valve is employed in accordance with the present invention.
Assuming that the truck 30 is in the position shown in FIG.
2, the main control valve 206 will be activated to direct
hydraulic fluid to flow under pressure through path 210 of
the system 200, in the direction of the arrow, thereby
causing the cylinders 74-75 and 134-135 to extend thus
tilting the tilting bed 38. Further, assuming that the
truck 30 is in the position shown in FIG. 5, the main
control valve 206 will be activated to direct hydraulic
fluid to flow under pressure through path 211, in the
direction of the arrow, to cause the cylinders to retract
from their extended position.
Importantly, in accordance with FIG. 13, it should be
noted that when the hydraulic fluid is flowing in the
direction of an arrow, the flow in the corresponding
opposing line is reversed. For example, hydraulic fluid
would flow according to path 210 to extend the tilting
.cylinders 74-75 and 134-135. With this direction of flow,
the fluid in path 211 would be reversed thus returning
hydraulic fluid to the main control valve. Similarly,
hydraulic fluid would flow according to path 211 to retract
the tilting cylinders 74-75 and 134-135. Accordingly, the
CA 02216497 1997-09-24
direction of flow in path 210 would be reversed thus
returning hydraulic fluid to the main control valve.
Further, it should be understood that in the following
that each reference to a"path" corresponds to a hydraulic
hose or line that actually carries the hydraulic fluid. In
the present invention, the hydraulic hoses 199 (as seen in
FIG. 7) are typically routed along the tilting bed 38 and
frame assembly 32, branching to the hydraulic device being
served. Additionally, it should be noted that a complete
box denoted by broken lines, such as box 212, indicates that
the components illustrated within are installed as a single
unit on an actual truck.
Considering now in more detail hydraulic flow path 210,
which extends cylinders 74-75 and 134-135, the hydraulic
flow is directed to a gear type flow divider 214 that
divides the hydraulic flow in a 3 to 1 ratio wherein path
215 receives 3-parts and path 216 receives 1 part. it
should be noted that path 215 flows to the first actuators
66 that tilt the tilting bed 38, and that path 216 flows to
the second actuators 68 that drive, i.e., pivot, link member
56. In this way, the flow divider 214 metes out the flow of
hydraulic fluid in a predetermined ratio, i.e., 3 to 1: 3
parts to hydraulic cylinders 74-75, and 1 part to hydraulic
cylinders 134-135, thereby synchronizing their movement. It
should be understood that in this specification, the term
synchronizing is used to mean only that the first and second
'i k
CA 02216497 1997-09-24
actuators 66-68 operate together, at the same time, but at a
predetermined unequal relative rate. More specifically,
hydraulic cylinders 74-75 operate at exactly three times the
rate of hydraulic cylinders 134-135. Accordingly, flow to
path 216 causes cylinders 134-135 to extend thereby pivoting
the link member 56. Path 215 is further directed through
flow control valve 221, and then through path 217, through a
1 to 1 flow divider 219 which splits the flow in equal parts
to paths 220 and 221. This causes hydraulic cylinders 74-75
to extend.
Now with the tilting bed as illustrated in FIG. 5, in
order to return the tilting bed 38 to its horizontal
position, the main control valve 206 is activated to direct
flow to path 211. Accordingly, the hydraulic flow is
directed to a gear type flow divider 222 that divides the
hydraulic flow in a 3 to 1 ratio wherein path 223 receives 3
parts, and path 224 receives 1 part. It should be noted
that path 223 flows to the first actuators 66, and path 224
flows to the second actuators 68. Accordingly, flow to path
224 causes cylinders 134-135 to retract thereby pivoting the
link member 56 to the position of FIG. 2. Path 223 is
further directed through flow control valve 225 then on
through a 1 to 1 flow divider 226 which splits the flow
equally into paths 228 and 229 which causes cylinders 74-75
to retract, returning the tilting bed 38 to the horizontal
position.
CA 02216497 1997-09-24
It should be noted that in the preferred embodiment,
the hydraulic flow paths to and from the first and second
actuators 66-68 is protected by various devices that
relieve and/or prevent excessive pressures from developing
that are too high for the system. For example two pilot
operated relief valves 232-233 are combined to form a
cushion valve that serves to reduce system surge created by
reversing the direction of hydraulic flow. Further, safety
relief valves 236, 237, 238 and 239 are provided to protect
against fluid expansion caused by heat. In addition, a
plurality bf cushion valves are provided by combining pairs
of pilot operate relief valves 240, 241, 242, and 243. The
cushion valves are provided to prevent chatter that could
arise from the merging of separate flows of hydraulic fluid.
Beyond this, a plurality of "four port load locks" 246,
247 and 248, which include pilot-to-open check valves, are
provided for safety purposes. For example, if a line to or
from a cylinder ruptured, like one along path 221, fluid
pressure would be maintained in cylinder 74 thus preventing
the same from lowering or raising at a dangerous rate.
Also, flow control check valves 250-251 are provided for
control purposes to augment the flow control valves 221 and
225. Similarly, for controllability reasons, internal
crossover relief valves 253-254 are provided so that the
rate of flow through flow control valves 221 and 225 can be
adjusted to any desired level.
4 3
CA 02216497 1997-09-24
Considering now in more detail, the hydraulic flow to
the reversible transport motors 170-171, the main control
valve 208 controls the flow thereto. Generally the
hydraulic flow can be directed along one of two paths 258
and 259. Path 258 causes the transport motors 170-171 to
rotate in a direction that results moving the carriage 154
toward the aft end 44 of the tilting bed 38. Path 259
causes the carriage to move toward the forward end 40 of the
tilting bed 38. Thus, for the carriage to move toward the
aft end 44, the hydraulic flow is directed along path 258
where the flow branches to path 262 and path 263 where the
flow reaches transport motor 170 after traveling through one
of the two pilot-to-open check valves found in the four port
load lock 265, and reaches transport motor 171 after
traveling through one of two pilot-to-open check valves
found in the four port load lock 266.
Conversely, directing the hydraulic flow along path 259
reverses the transport motors 170-171 to rotate in the
opposite direction which results in moving the carriage=154
toward the forward end 40 of the tilting bed 38. Thus the
hydraulic flow through path 259 continues until the flow
branches to path 268 where it continues to motor 170 after
passing through one of two pilot-to-open check valves found
in the four port load lock 265. Similarly, the flow
branches to path 269 where it continues to motor 171 after
CA 02216497 1997-09-24
passing through one of two pilot-to-open check valves found
in the four port load lock 266.
It should be noted that after passing through the main
control valve 208, the hydraulic flow first passes through a
pair of cushion relief valves, i.e., cross-port relief
valves, that assist to stabilize excessive pressures that
develop in that portion of the system.
Finally, it should be noted that a pair of pressure
relief valves 274-275 are connected to the hydraulic path
that leads to the main control valves 206-208. Pressure
relief valve 274 is a direct acting relief valve set at
3,000 psi; and pressure relief valve 275 is a internal pilot
relief valve.
It should be appreciated that the foregoing detailed
discription is the preferred embodiment of the present
invention. However, alternate embodiments that come within
the spirit of the invention could be easily practiced. For
example, in the present invention, the first actuator
comprises a pair of spaced hydraulic cylinders 74-75. This
construction could be modified to include only one centrally
disposed hydraulic cylinder 146 as illustrated in FIG. 12.
Also, a centrally located single cylinder so arranged could
likewise be adapted to the link member 56 as well as
illustrated in FIG. 11.
Further, each of the hydraulic cylinders 74-75 or 146,
could be replaced by an unyielding structural member such as
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CA 02216497 1997-09-24
a steel tube. With this arrangement, only the link member
56 would be connected to an actuator, i.e., second actuator
68. In this way, the tilting bed 38 would tilt about the
bed pivot axis 48, and shift rearward as the link member 56
pivots about the link pivot axis 99 responsive to actuation
of the second actuator 68.
In operation, let it be assumed that the tilting bed
occupies its initial or normal horizontal position as
depicted in FIG. 2. The method for loading and unloading
payloads is as follows. The user begins by actuating the
first and second actuators 66-68 wherein the tilting bed 38
pivots at the bed pivot joint 46, elevating the forward end
40 thereof, and the link member pivots shifting the tilting
bed 38 rearward and downward. With the tilting bed 38 in the
tilted position, a payload can be loaded onto the payload
support structure 52. Finally, the action of the first and
second actuators 66-68 is then reversed to return the
tilting bed to its original horizontal position with the
payload loaded thereon. Unloading the payload is the
reverse of the above noted steps.
To prevent the payload support structure 52 from
advancing too far forward in the loading process, a Spring
retention assembly 278 is provided as illustrated in FIGS. 8
and 12. The spring retention assembly 278 comprises a
spring loaded hook 280 disposed to engage a retention bar
282 that is fixed to the payload support structure 52. In
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CA 02216497 1997-09-24
this way, as the payload support structure 52 advances along
the tilting bed 38, the spring loaded hook 280, and the
spring thereof is compressed, thus providing increasing
resistance to further advancement.
Finally, the present invention further includes a rear
mounted bumper and light bracket 284 disposed to cover the
rear end of the frame assembly 32 when the tilting bed 38 is
in the horizontal position. The light bracket 284 is
mounted to the link member 56. Thus, because, the link
member 56 pivots rearward during the tilting process, the
light bracket likewise pivots.
Having illustrated and described the principles of my
invention in a preferred embodiment thereof, it should be
readily apparent to those skilled in the art that the
invention can be modified in arrangement and detail without
departing from such principles. Further, it is to be
understood that the invention is capable of use in various
other combinations and environments and is capable of
changes or modifications within the scope of the inventive
concept as expressed herein. I claim all modifications
coming within the spirit and scope of the accompanying
claims.
y-4-
