AU2004205202B2 - A Latch Mechanism for a Trailer - Google Patents

Description

A Latch Mechanism for a Trailer Field of the Invention This invention is directed to a latch mechanism which is simple in design, and relatively discreet, and which finds particular application for use on utility trays and box trailers. The invention will be described with reference to a latch mechanism for this use but it should be appreciated that no particular limitation is meant thereby and it is envisaged that the latch mechanism may also be used on other members.

Background Art A vehicle utility tray or a box trailer typically comprises a floor. To stop items from falling off the tray or box trailer, it is common to provide sidewalls.

Typically, there will be provided a pair of sidewalls and an end wall. The sidewalls are typically called "side gates" and the end wall is typically called a "tailgate". This terminology can of course vary between countnries.

The end wall (tailgate) is typically movable between an upright closed position and an open position. Most commonly, the tailgate can pivot between the upright closed position and a horizontal open position or a completely dropped-down vertical open position. Sometimes, the tailgate can pivot like a door from one end.

Sometimes, the tailgate can be entirely removed from the tray.

Most commonly however, the tailgate is pivotally moveable between the upright closed position and the horizontal or dropped-down open position. It is therefore necessary to provide some manner of latching of the tailgate such that the tailgate does not inadvertently drop open. A very simple mechanism to achieve this is to provide a pair of projecting pins which project through openings in the tailgate when the tailgate is closed. The ends of the pins have a drilled hole and a circlip is pushed through the hole to prevent the tailgate from opening. While this mechanism is simple, the circlips are continuously being lost, the holes are often filled with dirt, and attachment and removal of the circlips is fiddly.

Many utilities, and some box trailers, also have the sidewalls able to move between the upright closed position and a dropped-down open position, and these also need latching.

For this reason, it is more common to provide some form of latching mechanism that comprises a latch pin to latch the tailgate (and/or the side gate) in 2 position.

It is known to provide a latch pin which comprises an elongate pin member which can be slid manually between a forward closed position where the tailgate/side gate is closed and a retracted position where the tailgate/side gate can be opened. A disadvantage with this type of mechanism is that the latch pin can rattle and it is envisaged that the latch pin could also inadvertently slide to the open position.

Thus, it is also known to provide a latch pin containing a spring which pushes the latch pin into the forward closed position. To open the tailgate/side gate, it is necessary to pull the pin back against the bias of the spring. A disadvantage with this arrangement is that a tailgate will typically contain a pair of latch pins, one on each side edge of the tailgate. If the tailgate is quite wide, it is necessary for a person to stretch to grasp and pull back both latch pins against the bias of the respective springs. Also, this type of latch mechanism can still rattle which can be quite annoying.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Object of the Invention 2 0 It is an object of the invention to provide a latch mechanism which is particularly suited for utilities and box trailers and which may overcome at least some of the above-mentioned disadvantages or provide a useful or commercial choice.

In one form, the invention comprises a latch mechanism, the mechanism comprising a latch pin which is reciprocal between a forward latching position and a retracted unlocking position, a spring to bias the latch pin into the forward latching position, a handle which can be grasped to pull the latch pin from the latching position to the unlocking position, a panel to which the latch pin can be supported either directly or indirectly, and a slot extending through the panel, the slot having a first part which is generally in line with the longitudinal axis of the latch pin, and a second part which is at an angle to the first part, the latch pin being supported on one side of the panel, the handle extending through the slot and being operable from the other side of the panel, the handle being movable along at least part of the first part of the slot and along at least part of the second part of the slot, the pin being movable between the latching position and the unlocking position when the handle is in the first part of the slot, and the pin being held in the unlocking position when the handle has been moved to the second part of the slot.

This arrangement provides a simple yet robust mechanism which enables a tailgate to be opened and closed and where the mechanism enables the latch pin to be held in the retracted position in a simple but efficient manner.

The latch mechanism can be made slimline and simple in construction, and is easy to adjust to reduce noise and vibration. The latch mechanism can be discreetly incorporated into the utility side wall and the tailgate. If desired, the latch mechanism can be made from corrosion resistant material such as galvanised steel or stainless steel.

The latch mechanism may include a location pin. The location pin may be required for utility panels, and may be formed from metal such as mild steel. The location pin can be welded or otherwise attached into a hole formed in the utility panel. The location pin will typically contain an opening into which the latch pin can pass. The opening may be configured to prevent rotation of the latch pin about the longitudinal axis of the latch pin when the latch pin passes into the location pin. This will be described in greater detail below.

The tailgate will typically have a pair of latch mechanisms, one on each edge of the tailgate. This will be the case with tailgates that pivot between a vertical closed position and a horizontal or drop-down open position. For a tailgate that is hinged from one side of the utility or trailer, a single latch mechanism may be required.

If the latch mechanism is also used on the side gate, a single latch mechanism will typically be provided on a front edge of the side gate (that is the edge closest to the vehicle cabin). However, no particular limitation is meant thereby and a latch mechanism may also be provided on the rear edge of the side gate (that is the edge closest to the tailgate).

The latch pin will typically comprise an elongate metal pin and, in a preferred embodiment, will be made of stainless steel. The latch pin may have any suitable length and it is envisaged that the latch pin will have a length of between 250 millimetres and typically between 80-150 millimetres. The latch pin may have any suitable diameter or cross-section and it is envisaged that the latch pin will have a diameter or cross-section of between 4-20 millimetres and typically between 5-10 millimetres.

A spring may be provided to bias the latch pin into the forward latching position. Any suitable type of spring may be used, but it is considered most useful to have a helical spring which extends about the latch pin. This arrangement is known.

However, other types of springs could be used including a leaf spring, a rubber biasing member and the like. No particular limitation should be placed on the invention by the term "spring".

The latch mechanism contains a handle that can be grasped to pull the latch pin into the retracted position. There will be no need to place any particular limitation on the type, size and shape of the handle. In an embodiment, the handle comprises a "knob" type handle. The handle may be attached directly to, or indirectly to, or operatively connected to, the latch pin. Suitably, the latch pin is provided with a hole and the handle is provided with a projection that can fit into the hole to attach the handle to the latch pin. The handle is typically attached to the latch pin in the middle region of the latch pin. This arrangement also enables the handle to form a "stop" for the helical spring.

The latch mechanism works in association with a panel to which the latch pin can be supported. The panel will typically comprise the tailgate or the side gate or similar panel that can be moved between the open position and the closed position. The latch pin will typically be indirectly supported by the panel and may be supported by a bracket which is attached (typically by welding or by fasteners) to the panel.

The bracket may comprise an L-shaped bracket member having one leg attached to the panel and the other leg extending substantially at right angles to the panel. A hole can be provided through the other leg through which the latch pin can move. The other leg can also provide a stop member for the spring. This will be described in greater detail below. However, no particular limitation should be placed on the invention on the precise shape and configuration of the bracket.

The panel is provided with a slot. The slot has a first part which is generally in line with the longitudinal axis of the latch pin, and a second part which is at an angle to the first part. In a simple embodiment, the slot is L-shaped with one part being in line with the latch pin and the other part being substantially at right angles to the longitudinal axis of the latch pin. However, the slot need not be an Lshaped slot and may also comprise different configurations providing that it can function to hold the handle and therefore to hold the latch pin in the retracted position.

The slot may have any suitable length and width. This will depend in part on the "stroke" of the pin. Typically, the length of the first part will be between 10-50 millimetres and typically between 25-40 millimetres, and the length of the second part can be between 5-30 millimetres and typically between 5-15 millimetres. The second part can function to hold the handle in the "retracted" position and therefore the length of this second part need be sufficient only to allow the handle to be held. The length of the first part should be at least that which is required for the latch pin to move between the latching and the unlocking position. The width of the slot will vary and will depend primarily on the size of the part of the handle that projects through the slot. Typically, the width will be between 5-15 millimetres and preferably between millimetres.

If desired, some form of profile may be provided in the slot to facilitate positioning of the handle. This profile may comprise a projection in the slot, a shoulder in the slot, a recess in the slot and the like.

In a broad form, the invention resides in a latch assembly to hold a panel member in a lock position, the latch assembly comprising a latch tongue which is movable between a locking position and an unlocking position, a handle to operate the latch tongue, the latch tongue being on one side of the panel member, the handle being operable from the other side of the panel member, and a slot provided in the panel member, the slot having a configuration to enable the handle to hold the latch tongue in the unlocking position.

Brief Description of the Drawings An embodiment of the invention will be described with reference to the following illustrations in which: Figure 1 illustrates a latch mechanism in the latched position and from the "inside" of the panel.

Figure 2 illustrates the latch pin.

Figure 3 illustrates the latch handle.

Figure 4 illustrates the location pin.

Figure 5 illustrates a tailgate showing a latch mechanism on each edge of the tailgate.

Figure 6 illustrates two versions of the slot shape.

Figure 7 illustrates a side gate showing a single latch mechanism on the forward edge of the side gate.

Figure 8 is a plan view and a side view showing attachment of the location pin.

Detailed Description Referring to the illustrations, and initially to figure 1, there is illustrated a latch mechanism which basically comprises a latch pin 10, a spring 11, a handle 12 (only part of the handle being visible), a panel 13 and a slot in the panel which is generally L-shaped and which contains a first part 14 and a second part Latch pin 10 is supported by a upstanding leg 17 containing a hole through which latch pin 10 can pass. Spring 11 is sandwiched between upstanding leg 17 and handle 12. Therefore, when the handle 12 is pulled back, this will cause compression of spring 11. Put differently, spring 11 functions to bias latch pin 10 to the forward latching position. The position illustrated in figure 1 is the forward latching position where panel 13 is locked to post 18. This occurs because latch pin passes through an opening in the edge of panel 13 and into post 18.

Briefly, latch pin 10 can be retracted by grasping handle 12 and pulling handle 12 rearwardly such that handle 12 passes along the first part 14 of the slot.

When the handle has been pulled back to the rear of the first part 14 of the slot, latch pin 10 has now been retracted out of engagement with post 18. Handle 12 can now be rotated upwardly into the second part 15 of the slot. This causes latch pin to also rotate about its longitudinal axis. When the handle is in the second part 15 of the slot, pin 10 cannot move to the forward latching position as it is held back by engagement of the handle in second part 15 of the slot. The only way that the pin can be moved back to the latching position is to move the handle downwardly such that it moves out of the second part 15 of the slot and back into the first part 14 of the slot after which time the pin can move forwardly into the latching position under the influence of spring 11.

Figure 2 illustrates the latch pin 10. The latch pin is provided with an opening 19. Figure 3 illustrates the latch handle which in the particular embodiment is a knob-like handle. The handle has a forward part 20 that passes into opening 19.

Thus, handle 12 is engaged directly to latch pin Figure 4 illustrates a location pin 21 which is used for utility panels.

Figure 8 illustrates how the location pin 21 is attached to a panel. Location pin 21 includes an opening 22 into which the forward end of latch pin 10 can extend.

Particularly illustrated in the figure 8 top view is that opening 22 is not entirely circular and has flattened side portions.

The front part at least of latch pin 10 also contains flattened side portions such that when the latch pin passes into opening 22 of location pin 21, the latch pin 10 is held snugly and cannot rotate and rattle.

Figure 5 illustrates a tailgate and particularly illustrates two latch mechanisms on opposed edges of the tailgate. Figure 6 illustrates two slot designs in the panel. Basically, the main difference is that the first part 14 (that is the part which is in line with the longitudinal axis of latch pin 10) is longer in "detail A" and shorter in "detail which means that the latch pin travels along a longer distance in detail A and a shorter distance in detail B.

Figure 7 illustrates a side gate and illustrates a single latch mechanism 23 positioned at one edge of the side gate.

The latch mechanism can be designed to be a slimline and corrosion resistant latch that allows adjustment to reduce noise and vibration. The latch is discreetly incorporated into the utility side and tailgate thus ensuring it is an integral part of the tray design.

Throughout the specification and the claims (if present), unless the context requires otherwise, the term "comprise", or variations such as "comprises" or "comprising", will be understood to apply the inclusion of the stated integer or group of integers but not the exclusion of any other integer or group of integers.

Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

It should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims (9)

1. A latch mechanism comprising a latch pin which is reciprocal between a forward latching position and a retracted unlocking position, a spring to bias the latch pin into the forward latching position, a handle which can be grasped to pull the latch pin from the latching position to the unlocking position, a panel to which the latch pin can be supported either directly or indirectly, and a slot extending through the panel, the slot having a first part which is generally in line with the longitudinal axis of the latch pin, and a second part which is at an angle to the first part, the latch pin being supported on one side of the panel, the handle extending through the slot and being operable from the other side of the panel, the handle being movable along at least part of the first part of the slot and along at least part of the second part of the slot, the pin being movable between the latching position and the unlocking position when the handle is in the first part of the slot, and the pin being held in the unlocking position when the handle has been moved to the second part of the slot.

2. The mechanism as claimed in claim 1, including a location pin into which a forward end of the latch pin can pass when the latch pin is in the forward latching position.

3. The mechanism as claimed in any one of the preceding claims, wherein the panel comprises a tailgate panel and/or a side gate panel.

4. The mechanism as claimed in any one of the preceding claims, wherein the latch pin has a length of between 50-250 millimetres and preferably between 150 millimetres.

The mechanism as claimed in any one of the preceding claims, wherein the handle is attached directly to the latch pin and extends through the slot.

6. The mechanism as claimed in any one of the preceding claims, wherein the slot is substantially L-shaped with one leg comprising the first part and the other leg comprising the second part.

7. The mechanism as claimed in any one of the preceding claims including a bracket member comprising a leg extending from the panel and containing a hole through which the latch pin can pass.

8. The mechanism as claimed in claim 7, wherein the spring is a helical spring which extends between the bracket member and the handle.

9. A utility tray or a trailer containing at least one latch mechanism as 9 claimed in any one of the preceding claims, A latch mechanism substantially as hereinbefore described with reference to the drawings. Dated this 2 5 th day of August 2004 Pollard's Pty Ltd By their Patent Attorneys CULLEN CO.