AU689631B2 - Self-opening tailgate assembly - Google Patents

Description

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-1- P'01'O0O I Regulalion 3 2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

r r s Name of Applicant: Actual Inventors: Address for service MINEQUIPT PTY LTD Geoffrey HAVILAND and Peter Anthony WILIAMS in Australia: CARTER SMITH BEADLE 2 Railway Parade Camberwell Victoria 3124 Australia Invention Title: SELF-OPENING TAILGATE ASSEMBLY Details of Associated Provisional Application: PM8845 filed 17 October 1994 The following statement is a full description of this invention, including the best method of performing it known to us I' LLII I -2- BACKGROUND OF THE INVENTION This invention relates to a self-opening tailgate assembly and relates particularly to a tailgate assembly for trucks, including off-road, heavy duty trucks and dump trucks, which have a body pivotally mounted to the truck chassis.

Automatically opening tailgates have previously been proposed. In one proposal, a tailgate is provided with side arms which are pivotally attached partway along their length to the truck body. Chains or cables are attached to forward extensions of the arms and to the truck chassis which, when the body is pivoted on the chassis to discharge a load, causes the tailgate to rotate relative to the body.

One such arrangement is shown in United States Patent No. 3,751,112 to Hagenbuch in which a tailgate assembly includes two side plates that are pivotally connected to the sides of the body of the truck. A pair of outriggers are mounted on the truck chassis, the outer ends of the outriggers being connected to forwardly extending sections of the side plates to cause the tailgate to rotate when the truck 15 body is pivoted on the truck chassis.

A modified form of this arrangement is illustrated in Australian Patent No.

.g 599594 dated 24 July 1986. With this arrangement, a single chain is attached to the forwardly ext nding ends of the side plates, or side arms, the chain (or cable) passing around rollers mounted on the sides of the truck body. This arrangement obviates the need for outriggers which may cause difficulty on a truck chassis.

While the arrangements illustrated in the above-referenced patents are relatively effective to automatically open a tailgate of a truck, they are not necessarily effective in ensuring that the load carried by the truck is dumped quickly Sand cleanly. With the above-described arrangements, the rate of opening of the tailgate is such that, during initial body movement, the tailgate is relatively slow to open. This can inhibit the dumping of a load, and even cause uneven dumping, until such time as the body has pivoted a substantial extent.

The timing of, and the rate of opening of the tailgate can be controlled by using means, such as hydraulic cylinder means, connected to the chain (or cable) and actuatable to cause pivotal movement of the tailgate either without a corresponding DCCTG.916179 CAP 10 October 1995 II I I I -3pivotal movement of the truck body or during such pivotal movement. However, such additional means, and associated hydraulic control circuitry, would add significantly to the cost of an automatic tailgate system and adds complexity to the truck structure.

It is therefore desirable to provide an improved form of self-opening tailgate for tipping trucks and dump trucks.

It is also desirable to provide an improved construction of self-opening tailgate which is relatively simple and economical to manufacture.

It is also desirable to provide an improved construction of self-opening tailgate which obviates at least some of the disadvantages of the existing automatic tailgate systems.

It is further desirable to provide an improved construction of automatic tailgate which can be retro-fitted to existing vehicles.

It is also desirable to provide an improved automatic tailgate which is reliable 15 in operation.

It is also desirable to provide an improved automatic, self-opening tailgate which can be locked in a closed position.

SUMMARY OF THE INVENTION In accordance with one aspect of the invention there is provided a selfopening tailgate assembly for a truck having a tipping body pivotally mounted on a truck frame and including side walls and bottom wall means, the body being movable between lowered and raised positions, said tailgate assembly comprising a rear wall means forming the tailgate and side arms extending forwardly from each end of the tailgate substantially alongside the side walls of the body, forward ends of the arms being pivotally attached to the side walls, a guide for a flexible chain, rope or cable means carried on each side wall forwardly ot the respective pivotal arm attachment, and flexible chain, rope or cable means connected to the truck frame and to each respective arm at a position spaced from the arm pivot attachment towards the rear wall means, each said flexible chain, rope or Ltble means being engaged with the respective guide.

DCC TG:16179 CAO 10 October 1995 -4- In a preferred form of thle invention, thle pivotal attachment of thce armis to thle side walls is located substantially forwardly of the pivotal attachment of thle body to the truck frame. The guide is mounted above a line interconnecting thle location of the attachment of the chain, rope or cable to the arms and the pivotal attachment of the arms to the side walls.

In operation, pivotal movement of the truck body from the lowered position towards the raised position tensions the chain, rope or cable. By appropriate location of the pivotal attachment of the arms to the body, the location of the guide and the attachment of the end of the chain, rope or cable to the respective arms, the tailgate assembly is caused to pivot about the pivotal attachment of the arms to thle side walls during pivotal movement of the truck body towards the raised position.

The geometry of the arrangement can be designed so that a substantial opening of the tailgate occurs during initial pivotal movement of the body from the lowered position. This ensures that the tailgate is quickly opened on initial pivotal movement of the body and a load carried in the body can be dumped quickly and efficiently.

In order that the invention is more readily understood, one embodiment **:thereof will now be described with reference to the accompanying drawings wherein: Fig. 1 is a side elevation view of a dump truck embodying the invention; Fig. 2 is a view similar to Fig. I showing the dump truck body in a slightly raised position; Fig. 3 is a view similar to Fig. 1 showing the dump truck body in a fully raised position; 4 Fig. 4 is a part end view of the structure of Fig. 1: and Fig. 5 is a view of one form of cable guide used in the performance of the invention.

Referring to the drawings a dumnp truck 12 has a tipping body 14 carried on a chassis or frame 16 and movable about pivot 17. The body 14 may have a canopy 18 which extends over the cab 19 of the vehicle to protect the cab 19 when the vehicle is being loaded.

DCC TG:i116179 CAP conI'Q October 19" The body 14 is formed with opposed side walls 21. a front wall 22 and a bottom wall 23.

A tailgate assembly 24 comprises a rear wall, or tailgate, 26 with a pair of side arms 27 extending forwardly from the rear wall 26. The rear wall 26 acts to substantially close the otherwise open rear of the body 14 when the tailgate assembly 24 is in the close position as shown in Fig. 1.

Each side arm 27 is pivotally connected to a respective side wall 21. Thle pivotal connection may comprise a pivot pin 28 fixed to the respective side wall 21 and engaged with a corresponding bush (not shown) carried by the forward end of the side arm 27.

A guide 29 for a flexible chain, rope, cable or the like, is mounted on each side wall forwardly of the pivot pin 28. One particular form of guide 29 is shown in Fig. 5 in which a guide pulley 31 is rotatably mounted on a shaft 32 which is secured by a bolt 33 in a sleeve 34 carried by the side wall 21.

A flexible chain, rope or cable, and more particularly a steel cable 36 is connected at one end to the side arm 27 and to the truck frame or chassis 16. The cable 36 passes around the guide pulley 31 which is located above a line interconnecting the position of connection of the cable 36 wvith the side arm 27 and the pivot pin 28 whllereby the cable 36 is able to cause pivotal movement of the side arm 27 about the pivot pin 28. Naturally, a cable is connected to each side arm 27.

The angle between the cable run from the guide pulley 31 to the connection with the ann 27 and a line between the cable connection and the arm pivot is preferably greater than 100. The connections to the respective side arms is 0 preferably towards the tailgate ends of the arms as shown in Fig. 1, although the optinmm position will be determined by the geomnetry of the structure including the relative locations of the guide pulley 29 and pivot 28.

An assembly of deflecting rollers 37 is mounted at the lower end of each side wall 21 adjacent the bottom wall 23. The cable 36 on each side is attached to the truck frame 36 by fastening member 38, which is located beneath the body 14. The cable passes around the deflecting rollers 37 which maintain an appropriate direction DCC TO ,16179 CAr cobrI0 10 October 1995 6of cable run during movement of the body 14.

In operation, during loading of thle dump truck 1 2, the tailgate assembly 24 is in the position as shown in Fig. 1 with the rear wall of the assembly closing the rear opening of the body 14.

Referring to Fig. 2, when the body 14 begins pivotal movement in order to dump the load, that movement results in the guide 29 pivoting upwardly about the pivot 17. At the same time, the pivot pin 28 also moves upwardly and rear-wardly.

The geometry results in the cable 36 causing the tailgate assembly 24 to pivot relative to the body 14 in the manner shown in Fig. 2. This pivotal movement causes the tailgate rear wall 26 to clear the rear opening in the body 14 and to move over the top of any heaped load in the body 14 before there is a substantial pivotal movement thereof.

Referring to Fig. 3, continued pivotal movement of the body 14 results in the tailgate assembly 24 pivoting well clear of the load to ensure free egress of the load from the body.

The arrangement of the cable 36, the guide 29, the location of the pivot pin 28 and the position of the pivot 17 ensure the quick opening of the tailgate when it is required most, i.e. on commencement of pivotal movement of the body 14. Thle location of the attachment of the free end of the cable 36 to the side arm 27 may be adjustable both along the length of the side arm 27 and in relation to thle relative height of the attachment on the side arm. Suich an adjustment mnay allow variation in the extent and rate of opening of the tailgate assembly in operation.

Further, the location of the guide 29 may also be adjustable to take account of differing loads and load conditions. More than one cable guide may be provided.

It will be appreciated that many modifications may be made in the design and/or construction (if a self-opening tailgate assembly in accordance with thle present invention. In one modification (not illustrated), a single cable 36 may extend from one side armn 27 through a channel or tube fixed to the frame 16 beneath the body 14 and to the other side arm 27 onl the opposite side of the vehicle.

In a furtther modification, a locking mechanism may be incorporated into or attached DCC.TG 016179 CAP0 eoc95 10 Octobe, 1995 -7to the tailgate assembly to lock the tailgate in a closed position when the body is in a lowered position. Such a lock may be released by interaction with the chain, rope or cable, such that the pivotal movement of the body both releases the lock and effects relative rotation of the tailgate assembly.

In a further modification, more than one guide pulley is carried on each side wall to change the direction of the cable run between the deflecting rollers 37 and the attachment of the cable to the side arms to thereby increase the angle of the cable for initial opening movement of the tailgate.

DCC TO #1 179 CAP 10 October 19M

Claims (8)

1. A self-opening tailgate assembly for a truck having a tipping body pivotally mounted on a truck frame and including side walls and bottom wall means, the body being movable between lowered and raised positions, said tailgate assembly comprising a rear wall means forming the tailgate and side arms extending forwardly from each end of the tailgate substantially alongside the side walls of the body, forward ends of the arms being pivotally attached to the side walls, a guide for a flexible chain, rope or cable means carried on each side wall forwardly of the respective pivotal arm attachment, and flexible chain, rope or cable means connected to the truck frame and to each respective arm at a position spaced from the arm pivot attachment towards the rear wall means, each said flexible chain, rope or cable means being engaged with the respective guide.

2. An assembly according to Claim 1 wherein the position of the .oe o connection of each chain, rope or cable means to the respective arm is adjustable :0 0: 15 relative to the pivotal attachment of the arms to the side walls. 0

3. An assembly according to Claim 1 or Claim 2 wherein the guides are 6 o omounted on the respective side walls such that the angle at a point of attachment of •o• 0* the chain, rope or cable means to the arm and formed by lines joining the guide, the point of attachment of the chain, rope or cable means to the arm, and the arm pivot 20 is greater than about 100.

4. An assembly according to any one of Claims 1 to 3 whc.in each said 0 guide comprises a pulley rotatably mounted to the respective side wall.

An assembly ;ording to any one of Claims 1 to 4 wherein said chain, rope or cable means comprises a single steel cable which extends through a channel on the truck frame beneath the body.

6. An assembly according to any one of Claims 1 to 5 wherein roller means is mounted on each side wall adjacent the bottom wall means and said chain, rope or cable means passes around the roller means which guides the chain, rope or cable means during tipping movement of the body.

7. An assembly according to any one or Claims 1 to 6 wherein said DCC TG #16179 RSI 16 January 199$ sM -9- tailgate includes lock means to lock it to the body, said lock means being disengaged by said chain, rope or cable means upon movement of the body from the lowered position.

8. A tailgate assembly substantially as hereinbefore described with reference to the accompanying drawings or incorporating one or more of the novel features herein disclosed. DATED: 16 January 1998 CARTER SMITH BEADLE Patent Attorneys for the Applicant: MINEQUIPT PTY LTD *o o* DCC:TG#16179 RSI 16 January 1998 I- ABSTRACT An automatically opening tailgate assembly for truck boJy (14) includes a tailgate (26) having a pair of forwardly extending arms (27) pivotally connected at their forward ends to the opposed side walls (21) of the body A cable (36) attached to the truck frame (16) passes around a guide on each side wall (21) and is connected to the respective arm (27) rearwardly of the pivot Tipping movement of the body (14) tensions the cable (36) and causes the tailgate (26) to open. *e ee e oo DCCTG #16179 CAP 10 October 1995 -I -L I