The invention relates to a dock leveller including a primary deck having attached thereto a relatively movable secondary deck.

The increase in interstate trade throughout the European Community, and indeed the world, has increased the frequency of loading and unloading of goods travelling between destinations. Typically, goods are loaded onto and unloaded from transport vehicles using a dock leveller which when positioned between a vehicle and a storage bay provides a length of decking which is aligned at a first end with the vehicle and at a second end with the storage bay. Thus decking is provided over which operators and machinery, such as fork lift trucks, can travel when loading or unloading a vehicle. It follows, that a dock leveller must be flexible in the height it can be positioned at either end above ground level and also in the effective length of the leveller so as to provide a decking of any desired height and length with a view to connecting a trailer and a storage bay as afore described. It also follows that dock levellers must be designed to fit against vehicle trailers and must also be durable so as to support operators and fork lift trucks during a loading and unloading operation.

However, existing dock levellers are ineffective in that many are not designed for intensive operations such as use twenty four hours a day seven days a week. This is mainly due to the way the dock levellers are constructed. For example, although dock levellers may include a main or primary deck and a secondary extendible deck, the means whereby the

two decks are connected theretogether is such that typically the every day stresses exerted on the dock leveller result in warping or breakage of the main deck usually at a site where the secondary deck bears against it; further breakage of the secondary deck also occurs at its outer most extended end where it projects beyond the primary deck and so is unsupported by the primary deck.

In addition, the degree of extension of the secondary deck is often inadequate and, in part, this inadequacy is determined by the aforementioned relatively ineffective way the secondary deck is supported, when extended, by the primary deck.

It is therefore an object of the invention to provide a dock leveller which overcomes all the above described disadvantages and is therefore suitable for use during intensive operations (that is almost continuous use accommodating, for example, a ten thousand kilogram single axle loading); automatically operable and including a secondary deck providing adequate extension.

According to the invention there is therefore provided a dock leveller including a primary deck and a relatively moveable secondary deck wherein the primary deck is provided with at least one guide member which extends substantially along the longitudinal axis of the primary deck and which guide member is adapted to slidingly mate with a cooperating member attached to the secondary deck so as to enable the secondary deck to extend in sliding fashion with respect to the primary deck.

In a preferred embodiment of the invention the main deck includes a plurality of aligned and spaced guide members, each adapted to accommodate a cooperating member provided on the secondary deck.

Preferably the reinforcing members comprise steel bars which ideally are shaped and configured so as to withstand a twenty thousand kilogram load and ideally a ten thousand kilogram load.

Preferably the steel bars comprise fifteen millimetre steel bars.

Preferably the steel bars are provided on the underside of the main deck.

In yet a further embodiment of the invention there is provided between the primary deck and guide members a stiffener plate.

In yet a further modification of the invention, an end of the main deck remote from the extendible end of the secondary deck is hingedly connected to a support so as to enable the inclination of the primary deck, with respect to the vertical, to be varied. In this latter embodiment, the hinged connection may be provided through one end of at least one guide member. In this latter construction, guide members not hingedly connected as afore described may terminate at a location inwardly spaced from the hinged region so as to provide access to said hinged regions for the purpose of repair, removal and the like.

Preferably the dock leveller includes an adjustable support means which enables the height of the leveller to be varied with respect to ground level.

Preferably the dock leveller includes an adjustable extension means which enables the secondary deck to be extended beyond the primary deck by a variable amount. Preferably this latter extension means comprises an extension ram such as a hydraulic ram.

It will be understood from the fore going that the interaction of longitudinal guides and cooperating members provides support for the secondary extending deck throughout the length of the main deck. All cooperating

members are therefore bearing against the guides thus distributing the load and ensuring a long service life for the dock leveller.

Ideally the extension means are operated by controls which are housed in a separate console on the loading dock so as to provide ease of maintenance. This console can have all the controls of the complete loading dock. The controls are ideally simplified in nature and have official indicators for ease of safety and operation.

An embodiment of the invention will now be described, by way of example only, with reference to the accompany drawings wherein:

Figure 1 represents a side elevation view of a dock leveller in accordance with the invention;

Figure 2 represents a plan view of the dock leveller shown in Figure 1 ;

Figure 3 represents an end view of the dock leveller shown in Figures 1 and 2;

Figure 4 represents an end view of part of a secondary deck extension means;

Figure 5 represents an end view of a hinge arrangement used in the dock leveller; and

Figure 6 represents a side elevation view of the hinge arrangement shown in Figure 5.

Referring to the Figures and firstly to Figure 1, there is shown a dock leveller including a main or primary deck 1 and under most thereof a secondary deck 2 mounted on adjustable, spaced pedestals 3. Pedestals

3 are vertically adjustable, using conventional means, so as to enable the height of decks 1 and 2 to be adjusted with respect to ground level 4.

At a first end 5, primary deck 1 is hingedly attached to cross support 6. This arrangement is shown in Figure 2 where it can be seen that four hinge mountings 7 are provided in spaced manner along the transverse length of end 5 of the dock leveller. Hinges 7 are arranged in two pairs, each pair being equidistant from the central longitudinal axis of deck 1 and further, the spacing between the hinges in each pair is the same either side of said longitudinal axis.

The under most side of primary deck 1 is provided with a number of aligned, spaced longitudinal guides 8a and δb. Guides 8b extend the entire longitudinal length of the main deck and thus terminate at the outer most end 5 of the main deck where the main deck is connected to cross support 6. Further, at end 5, the terminating ends of guides 8b are hingedly attached to mounts 7a of hinges 7. In contrast, guide members

8a terminate at a distance remote and inner most from this hinged region. This arrangement enables access to the hinged region for the purpose of repair, maintenance and removal or the like.

The hinges 7 are shown more clearly in Figure 5. It can be seen that guides 8b are of essentially square section and comprise two L-shaped members joined by welding at their lower most mid-point 15. Attached to the upper sides of L-shaped members is a flat bar 9 whose width is greater than that of guides 8a, 8b to facilitate attachment. Bar 9 is attached to the under most side of the primary deck 1 by welding or any other conventional means. Each of the upstanding sides of L-shaped members are provided with a single aperture, aligned with respect to each other, and adapted to accommodate a hinge pin 10. Adjacent either side of L-shaped members there is provided a pair of spaced brackets 11, each bracket 11 having an aperture adapted to accommodate hinge pin 10. Brackets 11 are shaped and configured so as to facilitate pivotal

movement of primary deck 1 about the hinge axis A. This shape and configuration is illustrated in Figure 6.

Referring again to Figure 1 , it can be seen that a secondary deck 2 is positioned beneath main deck 1 and comprises an upper outer deck 2a and attached to the lower rear most part thereof spaced lower slide members 2b which extend rearwardly beyond deck 2a. Slide members 2b are shaped and configured so as to slidably fit within guides 8a and 8b. Further guides 2b occupy substantially the length of guides 8a and 8b. Movement of slides 2b within guides 8a and 8b is brought about by hydraulic ram 12 which is attached to the under most side of a centrally positioned slide 2b. Figure 4 shows an end view of secondary deck 2 and clearly shows that slides 2b are of square section so as to fit within guides 8a and 8b. A stiffening plate (not shown) may be provided between slide 2b and deck 2a.

Although guides 8a, 8b and slides 2b are illustrated in square section it is not intended that the invention is to be so limited rather any appropriate section which allows the working of the invention falls within the scope of the patent.

Figure 3 shows an end view of the deck leveller and it can be seen that the under most surface of primary deck 1 is provided with eight guides 8a and 8b. Moreover four 8a guides are provided and four 8b guides are provided in a pattern which from left to right of Figure 3 reads 8b 8a 8b 8a 8a 8b 8a 8b. This arrangement provides for essentially outwardly provided hinges 7 along the transverse axis of deck 1. As mentioned, beneath primary deck 1 there is provided a secondary deck 2 whose rear most or inner most end is provided with slides 2b which slidably engage with guides 8a and 8b. The length of deck 2a may be varied according to a user's requirements. Hydraulic ram 12 is connected to the under most side of secondary deck 2 so as to displace secondary deck 2 in a forward

direction away from end 5 thus ensuring that deck 2 extends beyond main deck 1.

In addition, vertical support members 14 are provided towards either side of the deck leveller so as to support deck 2 when in a resting position and so safeguard against failure of ram 12.

The number and nature of guides 8a, 8b and slide members 2b will determine the load bearing capacity of the decking. Ideally guides and slide members of a length substantially equal to the length of deck 1 will be used and the number of guides and slide members provided along the transverse axis of deck 1 will be such as to ensure that the load bearing capacity of the deck is ideally uniformly distributed over substantially the area of deck 1.

In a variant of the invention a single guide member spanning a substantial lower most area of deck 1 may be provided and a single, preferably similar shaped, cooperating member or slide may be provided on deck 2 and adapted to move, ideally slidably with respect to said single guide.

In use, when secondary deck 2 is extended beyond main deck 1 , forces bearing on secondary deck 2 are transmitted, via guides 8a and 8b which act as reinforcing members over the entire area of the main deck thus enabling the deck leveller to support a substantial load and further enabling the deck leveller to be used during intensive operations. The deck leveller herein described thus represents a leveller which is sturdy and reliable.