CA2216497C - Truck mounted payload loading and unloading apparatus and method - Google Patents

Abstract

A truck mounted payload loading and unloading apparatus comprising a tilting bed supported over a frame assembly. The aft portion of the tilting bed being connected to the frame assembly by a link member disposed therebetween. The link member having a first end pivotally connected to the frame assembly at a link pivot joint. Wherein the link member is pivotable about the link pivot joint. The link member having a second end pivotally connected to the tilting bed at a bed pivot joint wherein the tilting bed pivot joints about the bed pivot joint about a substantially horizontal aft pivot axis. The tilting bed being pivoted by a first actuator operatively disposed between the frame and the tilting bed to drivingly engage the tilting bed and tilt the same about the bed pivot joint responsive to actuation of the first actuator. The bed pivot joint being movable in a direction parallel to the longitudinal axis of the vehicle and downward responsive to actuation of a second actuator operatively disposed between the frame and the link member. The movement of the first and second actuator being synchronized so that the same move in a predetermined manner wherein the aft end of the tilting bed shifts rearward and .downward responsive to actuation of the actuators.

Description

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 -- - - - -- --- -----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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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 ~

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 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.

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 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 - - - - ---- -----= ~

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.

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 from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

9a 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.

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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 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 {

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 - - --- -------------- --------- - -- ----------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 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 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

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 -------------- --------= 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 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 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 = 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.

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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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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 a3 = 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, ay 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 ------------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, 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 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, 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, - ------------------ ---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 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 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~

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 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'~

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 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.

- - ---------- -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 - --- - --- ------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, 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~

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 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 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.

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.

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 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 'AS

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 Li b 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-

Claims (8)

1. 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 said 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 connected 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.

2. A self-unloading vehicle as claimed in Claim 1, wherein the actuators are co-ordinated fluid actuators supplied from a common feed, with a flow divider valve, selectively operable to distribute fluid therebetween and thereby co-ordinate rela-tive actuator motion.

3. A self-unloading vehicle, as claimed in claim 1 or 2, wherein the tilt actuator is located forward of the pivot link member, toward a forward end of the load bed, and is opera-tively disposed to tilt the load bed about a bed pivot axis, thereby elevating the forward end; the link actuator being located toward a rearward end of the load bed, and is operatively disposed to displace the load bed rearward and downward.

4. A self-unloading vehicle as claimed in any one of claims 1 to 3, further comprising means for synchronizing link actuator and tilt actuator operation.

5. A self-unloading vehicle as claimed in any one of claims 1 to 4, with a hydraulic tilt actuator extendible between a retracted position, where a forward end of the tilting load bed is adjacent the vehicle chassis; and an extended position where the forward end is elevated, away from the vehicle chassis, and the tilting load bed pivot joints about a bed pivot axis; and a hydraulic link actuator disposed between the link member and the vehicle chassis, forward of the link pivot joint, extendible between a retracted position where a rear-ward end of the tilting bed is forwardly disposed, to an ex-tended position where the bed pivot joint axis shifts rearward and downward, and the rearward end of the load bed shifts rearward and downward.

6. A self-unloading vehicle as claimed in Claim 5, wherein the tilt actuator comprises a pair of spaced apart, side-by-side hydraulically operated, telescopic cylinders, and the link actuator comprises a pair of spaced apart, side-by-side hydraulically operated, telescopic cylinders.

7. A self-unloading vehicle as claimed in any one of claims 1 to 6, wherein the load bed comprises a pair of parallel side rails, and a payload conveyance mechanism with a carriage reciprocally movable upon the side rails; a payload support structure, detachably connected to the carriage, for receiving a payload, the carriage being movable from a first forward position, where the payload support structure is attached to the carriage, over the tilting bed, to a second aft position, where the payload support structure is dis-connected from the carriage.

8. A self-unloading vehicle as claimed in Claim 7, wherein said moving means comprises a chain, a chain drive motor and a plurality of sprockets.