Roll Trailers and loading of roll trailers on vessels

This invention relates to roll trailers and to methods of loading roll trailers onto a vessel.

Typically, a roll trailer is used on a Ro-Ro vessel and at a port to convey a load from dry land at a port onto a vessel, to carry the load on the vessel during its travel to another port and to carry the load from the vessel to dry land at the other port. Unlike a road trailer a typical roll trailer is not designed to travel long distances on roads and usually does not have a suspension system between the wheels and the body of the trailer. Also the wheels, which are typically wide, have solid tyres, which may be made of hard rubber. Other typical characteristics of a roll trailer are that it has a relatively low platform capable of receiving a heavy load which may be of the order of 100 tonnes weight and has openings in the top of its load carrying platform for receiving twistlocks which may be used to lock standard freight containers to the roll trailer.

When roll trailers are loaded on a deck of a roll-on roll- off vessel there may be a need to secure the trailers to the deck of the vessel, either as a routine procedure or if bad weather is expected. Without such securing there is a risk of the trailer shifting with the vessel or even toppling over. Because of the large weight of the trailer and its load, much shifting of the trailer can cause extreme damage to other cargo being transported by the vessel. Accordingly, it is known to lock the roll trailer to the deck of the vessel with suitable chains or other lashings

and for many years roll trailers have been provided on their sides with lashing bars to facilitate this procedure. Despite the presence of the lashing bars, however, the procedure for lashing a single roll trailer to the deck of a vessel is time consuming and it is often the case that there are a significant number of roll trailers, each of which has to be lashed to the deck.

It is an object of the invention to provide a method of loading roll trailers onto a vessel that facilitates securing of the trailers on the vessel. It is a further object of the invention to provide a roll trailer suitable for use in such a method.

According to a first aspect of the invention there is provided a method of loading roll trailers onto a vessel, the method including the step of positioning the roll trailers in end to end relationship with adjacent ends of trailers inter-engaged in such a way that relative horizontal transverse movement of the adjacent ends of the trailers is limited.

By adopting the simple expedient of having one end of a roll trailer engaging the adjacent end of another trailer it becomes possible to secure a series of roll trailers together in a very quick and simple manner. With such an arrangement the need for lashing of each roll trailer may be reduced or eliminated.

In order to keep relative movement between inter-engaged ends of trailers to a low level it is desirable that, when the adjacent ends of the trailers are inter-engaged, their

relative horizontal transverse movement is limited to less than 300 mm and preferably to less than 200 mm.

Whilst, as defined above, it is within the scope of the first aspect of the invention for the inter-engagement not to limit relative vertical movements of the ends of the trailers, it is preferred that the adjacent ends of the trailers are inter-engaged in such a way that relative vertical movement of the adjacent ends of the trailers is also limited. That may be of particular advantage in reducing the likelihood of a trailer toppling over. As with the limiting of the relative horizontal transverse movement, it is desirable to limit relative vertical movement between the adjacent ends of the trailers and it is therefore preferred that, when the adjacent ends of the trailers are inter-engaged, their relative vertical movement is limited to less than 150 mm and preferably to less than 80 mm.

It is within the scope of the invention for separate coupling devices to be provided between adjacent ends of the trailers to provide for their inter-engagement, but it is preferred that the adjacent ends of the trailers are themselves provided with coupling formations for enabling the ends of the trailers to inter-engage one another. Preferably the coupling formations comprise complementary male and female formations which directly inter-engage one another. Preferably the one or more male formations are provided on the end of one trailer and the female formation on the end of the adjacent trailer but another possibility is to have a mixture of male and female formations on each end. We have found that a simple male/female inter- engagement can be made very simply but still provide a

strong and secure fastening between the adjacent ends of the trailers. The inter-engaging male and female portions are preferably tapered and/or flared to allow initial engagement of the ends of the trailers at a position offset from the aligned position but to force the ends of the trailers into better alignment when the ends of the trailers are fully engaged. For example, the male formations may be tapered such that their distal ends are of smaller cross section and the female portions may be flared outwardly towards their open ends. Such an arrangement facilitates the inter- engagement of the trailers as they are loaded onto the vessel and also makes it easier to ensure, once one trailer is correctly positioned in the vessel, that subsequent trailers inter-engaged in a series with that trailer are correctly positioned.

The invention may be applied to a case where just two roll trailers are positioned in end to end relationship, but it is preferred that there are three or more roll trailers positioned in end to end relationship with adjacent ends of trailers inter-engaged in such a way that relative horizontal transverse movement of the adjacent ends of the trailers is limited. As will be understood the inter- engagement of the ends of each pair of inter-engaging trailers may be of any of the forms described above and, for example, relative vertical movement may also be limited. Each trailer in the series of trailers may have first and second ends with the first end of each trailer engaging the second end of the adjacent trailer except at the ends of the series of trailers where there is one first end and one second end that are not of course engaged with an adjacent end of a trailer.

Preferably, one end of a series of inter-engaged trailers engages a structural part of the vessel in such a way that horizontal transverse movement of the end of the series of trailers relative to the structural part of the vessel is limited. The structural part of the vessel may, for example, be a bulkhead. The engagement between the end of the trailer and the bulkhead may be of the same general form as the engagement between the adjacent ends of the trailers. Thus, for example, the engagement may also limit vertical movement and may involve engagement of male and female formations. More particularly the bulkhead may be provided with male formations for engaging female formations on the end of a trailer.

In an especially preferred form of the first aspect of the invention at least one of the trailers is fastened to the deck of the vessel by a fastening device fitted to said at least one of the trailers. By providing such a fastening, the securing of the series of trailers is enhanced because they are not only secured to one another but also to the deck of the vessel, either directly or via the inter- engagement with another trailer which is fastened to the deck of the vessel. The fastening device is preferably permanently secured to the trailer. The device preferably includes a rigid fastening member projecting downwardly from the trailer into engagement with the deck of the vessel when the trailer is fastened to the vessel. Preferably, the fastening member is able to be inserted downwardly from an upper release position into an opening in the deck of the vessel and into a first fastening position and then moved to a second locking position in which it cannot be withdrawn

directly upwardly out of the opening. The fastening member may be moved from the first position to the second position by rotation of the member. The rotation may be about a substantially vertical axis. In an especially preferred embodiment of the invention, the fastening device is a twistlock of similar design to that used to fasten freight containers to trailers.

In the case where the fastening member is moved from the first fastening position to the second locking position by rotation, the opening in the deck of the vessel is preferably defined by a non-circular aperture.

The fastening device may be manually operated but it is also possible for the fastening device to be automatically operated. The automatic operation may be caused by lowering one end of the roll trailer onto the deck of the vessel. Typically a roll trailer is loaded onto a vessel using a loading vehicle which lifts up one end of the roll trailer and which, once the trailer is in position on the vessel, releases that end of the trailer onto the deck of the vessel. Preferably a fastening device is fitted to each trailer. The fastening device may be fitted in the region of one end of the trailer. By virtue of the inter- engagement of trailer ends, such a fastening device may also effectively fasten the adjacent end of another trailer. Preferably each trailer has a pair of fastening devices provided on opposite sides of the trailer in the region of said one end of the trailer. Said one end of the trailer may be the first end or the second end referred to above and is preferably the first end, which may also be the front of the trailer.

According to the first aspect of the invention there is also provided a roll trailer having first and second opposite ends, each of the first and second ends being provided with coupling formations for enabling the first end of the roll trailer to engage the second end of another roll trailer of the same design in such a way that relative horizontal transverse movement of the adjacent ends of the trailers is limited.

As will be understood, the roll trailer defined above is suitable for use in the method defined above and the roll trailer may have further features making it suitable for carrying out the preferred and optional features of the method described above. For example, each of the first and second ends of the trailer may be provided with coupling formations for enabling the first end of the roll trailer to engage the second end of another roll trailer of the same design in such a way that relative vertical movement of the adjacent ends of the trailers is limited. The coupling formations at the first and second ends of the trailer may be complementary formations sized such that formations at the first end of the trailer are suitable for direct inter- engagement with formations at the end of another trailer having formations that are the same as the formations at the second end of the trailer. There may be one or more male formations at the first end of the trailer and one or more female formations at the second end of the trailer. The roll trailer may have ground engaging rollers that are closer to the second end of the trailer than to the first end of the trailer. The first end of the trailer may be the front of the trailer.

The inter-engaging formations may be tapered and/or flared to allow initial engagement of the first end of the trailer with the second end of another, similar, trailer with the ends of the trailers offset from an aligned position, but to force the ends of the trailers into better alignment when they are fully engaged.

The roll trailer may further include a fastening device fitted to the body of the trailer for fastening the trailer to a deck of a vessel. The fastening device may include a rigid fastening member for projecting downwardly into engagement with the deck of a vessel. The fastening member may be mounted for movement between an upper release position and a lower fastening position and may be further moveable from the lower fastening position into a lower locking position. The fastening member may be moveable from the lower fastening position into the lower locking position by a translational movement and/or by a rotational movement.

The fastening device may be manually operable or it may be automatically operable.

The fastening device may be fitted to the body of the trailer in the region of the first end of the trailer. A pair of fastening devices may be fitted to the trailer on opposite sides of the trailer in the region of the first end of the trailer.

One of the features described above in respect of the first aspect of the invention is the advantageous feature of fastening the trailer to the deck of the vessel by a

fastening device. That feature of the invention may be employed separately from the feature of ends of the trailers inter-engaging. Accordingly in a second aspect of the invention there is provided a method of loading a roll trailer onto a deck of a vessel, the method including the step of fastening the trailer to the deck of the vessel by a fastening device fitted to the trailer and including a rigid fastening member projecting downwardly into engagement with the deck of the vessel.

According to the second aspect of the invention there is also provided a roll trailer having first and second opposite ends, the trailer including a fastening device fitted to the body of the trailer for fastening the trailer to a deck of a vessel, the fastening device including a rigid fastening member for projecting downwardly into engagement with a deck of a vessel.

The method and the roll trailer according to the second aspect of the invention may incorporate any of the features described above of the roll trailer according to the first aspect of the invention. For example, the roll trailer may have ground engaging rollers that are closer to the second end of the trailer than to the first end of the trailer. Each of the first and second ends may be provided with coupling formations for enabling the first end of the roll trailer to engage the second end of another roll trailer of the same design in such a way that relative horizontal transverse movement and/or relative vertical movement of the adjacent ends of the trailers is limited. All of the other features described above in relation to the first aspect of

the invention may similarly be incorporated in the second aspect of the invention.

In preferred embodiments of the invention described below both the first and second aspects of the invention are employed in combination to provide an especially preferred method of loading roll trailers onto a vessel and a roll trailer for use in such a method. Nonetheless it should be understood that each of the first and second aspects of the invention may be employed without the other if desired.

By way of example embodiments of the invention will now be described with reference to the accompanying schematic drawings, of which:

Fig. 1 is a perspective view of a typical, known, form of roll trailer;

Fig. 2A is a side view of a pair of roll trailers, each embodying the invention, inter-engaged in end to end relationship;

Fig. 2B is a plan view of the pair of roll trailers shown in Fig. 2A;

Fig. 3A is a plan view, to a larger scale than Figs. 2A and 2B, of the adjacent ends of the pair of roll trailers shown in Figs. 2A and 2B, prior to engagement;

Fig. 3B is a plan view similar to Fig. 3A but showing the adjacent ends of the roll trailers inter-engaged;

Fig. 3C is a side view of the inter-engaged adjacent ends of the roll trailers shown in Fig. 3B;

Fig. 4A is a plan view of a front corner region of the roll trailer shown in Figs. 2A to 3C showing a first form of fastening device;

Fig. 4B is a side view of the corner region and fastening device shown in Fig. 4A;

Fig. 5A is an end view of a roll trailer similar to that shown in Figs. 2A to 4B, but having a modified form of fastening arrangement, the fastening arrangement being shown in an upper release position;

Fig. 5B is an end view of a corner region of the roll trailer shown in Fig. 5A, the fastening arrangement being shown in a lower fastening position; and

Fig. 5C is an end view similar to Fig. 5B but showing the fastening arrangement in a lower locking position.

Referring first to Fig. 1, the roll trailer shown has a platform 1 provided on top of a robust steel frame and surfaced mainly with wooden decking 2 but also with steel decking 3 in a region that overlies eight wheels 4 of the trailer. The wheels 4 are provided on adjacent axles and are closer to a second, rear, end 5 of the trailer than to a first, front, end 6. The roll trailer has container fixing apertures 7 at the corner of its decking and other suitable locations, to enable ISO freight containers to be fastened by twistlocks to the roll trailer. At the front end of the

roll trailer (not visible in Fig. 1) a fitting is provided to enable the trailer to be lifted by a gooseneck on a loading vehicle.

The sizes of roll trailers vary but in the particular example when the trailer has a length of 40ft (12192mm), the platform 1 is at a height of 700mm and the trailer is suitable for carrying a load of the order of 80 tonnes. The trailer body has a ground clearance of about 240mm.

When the trailer is loaded on a vessel and it is desired to secure the trailer to the deck of the vessel, it is lashed to the deck by suitable lashings and, to facilitate this, lashing bars 8 are provided along the entire length of each side of the trailer. Depending upon the load to be carried, it may be desirable to have vertical stanchions (not shown) projecting upwardly along the sides of the trailer and for that purpose stanchion pockets 9 are provided at intervals along the length of each of the sides of the trailer.

The roll trailer described above is in commercial use.

Referring now to Figs. 2A and 2B, and also to Figs. 3A to 3C and Figs. 4A and 4B, the roll trailers shown therein are generally similar to that shown in Fig. 1, but are provided with additional features as will now be described.

A first additional feature is that the roll trailers have male and female coupling formations at their ends to enable a first, front, end 16 of one roll trailer to engage a second rear, end 15 of another roll trailer. For example, in Figs. 2A and 2B, a pair of roll trailers 10 are shown,

each of the same design and including a platform 11 and wheels 14. As can be seen more clearly in Figs. 3A to 3C the front end 16 of each roll trailer 10 is provided with a pair of male formations 21 and the rear end 15 of each roll trailer 10 is provided with a pair of corresponding female formations 22. When the adjacent ends of the trailers are inter-engaged, as shown in Figs. 3B and 3C the male formations 21 are received within the female formations 22 and, consequently, relative horizontal movement transverse to the longitudinal axis of the trailers, and relative vertical movement, of the adjacent ends of the trailers is limited.

As shown in Figs. 3A to 3C the male formations 21 are tapered towards a distal end of relatively narrow cross- section and the female formations 22 flare outwardly towards their open ends.

Also visible in Figs. 3A to 3C is part of the fitting 23 for connection to the gooseneck on a loading vehicle, this fitting being unchanged from that employed in the roller trailer shown in Fig. 1.

In addition to the coupling formations shown in Figs. 3A to 3C, each roll trailer 10 is also provided with a pair of fastening devices, 30 located at opposite sides of the front end of the trailer as will now be described with reference also to Figs. 4A and 4B.

Each fastening device 30 is fitted to the body of the trailer and includes a fastening member comprising a rigid rod 31 carrying at its bottom end a non-circular flange 32.

The rod 31 is mounted for vertical sliding movement and is also provided with a pivotable handle 34 at its top end, by which the rod 31 can be rotated about its longitudinal (vertical) axis. Plates 31 define the limits of the vertical sliding movement.

As may already be understood, the fastening member is able to be twistlocked to a vessel deck in a similar manner to that in which twistlocks are used to secure freight containers. Thus the rod 31 and flange 32 is lowered from the position shown in Figs. 4A and 4B down through a non- circular opening 35 in the vessel deck, illustrated in dotted outline in Fig. 4B only. The non-circular opening 35 and the flange 32 are of similar cross-sectional shape with the flange slightly smaller than the opening. Consequently with the flange 32 and the opening 35 aligned, the flange 32 can be passed through the opening 35. The rod 31 is then rotated through about 90 degrees by a user operating the handle 34 and that brings the flange 32 into a position where it cannot be withdrawn from the opening 35 and the trailer is then locked by the fastening device to the vessel deck. As will be understood, to release the fastening of the roll trailer to the vessel deck, it is simply necessary for a user to rotate the flange 32 into alignment with the opening 35 and then raise the rod 31 back to the position shown in Figs. 4A and 4B.

In use, the roll trailers 10 are loaded into the hold of a roll-on, roll-off (Ro-Ro) vessel. A first trailer 10 is conveyed by a loading vehicle into the hold of the vessel and the rear end of the trailer manoeuvred to a position adjacent a bulkhead of the vessel that is provided with

projections of similar shape and position to the projections 21 on the front end of the trailer 10. The trailer 10 is then moved right up to the bulkhead and the projections on the bulkhead engage in the recesses 22 at the rear end of the trailer. At the front end of the trailer the rods 31 and flanges 32 on the pair of fastening members are then lowered so that the flanges enter openings 35 in the deck, the rods 31 are rotated and the front end of the trailer thereby locked to the vessel deck.

A second trailer is then conveyed by a loading vehicle into the hold of the vessel and the rear end of the second trailer is brought into inter-engagement with the locked down front end of the first trailer with the male formations 21 at the front of the first trailer engaging in the female formations 22 at the rear of the second trailer, as shown in Figs. 3B and 3C. Any misalignment of the trailers prior to their engagement is reduced as the trailers engage by virtue of the taper to the male formations 21 and the flare to the female formations 22. Once the first and second trailers are inter-engaged, the fastening devices at the front end of the second trailer are operated to lock the front end of the second trailer to the vessel deck.

A third trailer and one or more further trailers can then be added to the series of trailers in the same manner as described above for the second trailer.

It will be noted that in a fully loaded series of trailers each front end of each trailer, apart from the last trailer to be loaded, is locked down to the vessel deck and each rear end of each trailer is inter-engaged with a locked down

adjacent front end of the adjacent trailer, apart from the rear end of the first trailer which is inter-engaged with the bulkhead. If desired, the front end of the last trailer to be loaded can be lashed to the deck of the vessel to secure it. It is then the case that both ends of every trailer are locked to the vessel deck.

In the embodiment of the invention described above the fastening devices are manually operable. Figs. 5A, 5B and 5C show an alternative form of fastening arrangement that is automatic; that is, as the front end of the trailer is lowered by the loading vehicle onto the deck the fastening devices automatically lock themselves in openings in the deck. That automatic fastening arrangement will now be described briefly with reference to Figs. 5A, 5B and 5C.

Fig. 5A shows the fastening arrangement before the trailer is disconnected from the loading vehicle. A locating rod 51 mounted on the body of the trailer is above and clear of an opening 52 in the deck 53. As in the case of the previous embodiment the fastening arrangement comprises two fastening devices located on opposite sides of the front end of the trailer. Adjacent to the rod 51 is a cranked locking lever having a locking arm 54 and an operating arm 55. The cranked locking lever is pivotally connected at a pivot 57 to the rod 51.

As the trailer is disconnected from the loading vehicle, the free end of the operating arm 55 (the right hand end as seen in Fig. 5B) is raised causing the locking lever to pivot anti-clockwise (as seen in Fig. 5B) and to move the locking arm 54 into alignment with an opening 59 in the deck of the

vessel adjacent to the opening 52, and allowing the rod 51 and the locking arm 54 to enter the openings 52 and 59 respectively.

As the trailer becomes fully disconnected the free end of the operating arm 55 is released and pivots under gravity in a clockwise direction (as seen in Figs. 5B and 5C) to the position shown in Fig. 5C where a lip 58 on the locking arm 54 engages under the surround to the opening 59 and thereby locks the trailer to the vessel deck.

Whilst the openings 52 and 59, may be substantially circular, they may also be in the form of slots running the length of one or more trailers.

As will be understood the steps just described are carried out in reverse when the trailer is to be unloaded from the vessel. Thus a simple and automatic arrangement for locking and unlocking the trailer is provided.