5 The present invention relates to an arrangement for supporting the front end of a trailer when parking the aforementioned trailer on board ships, railway wagons and other vehicles, comprising coupling means for the detachable attachment of the support to a trailer of the kind in question 0 and to a drivable loading vehicle, in conjunction with which the support consists of a beam extending across the trailer that is so arranged as to be borne at a distance from the deck or some other parking surface by bearers. Previously disclosed is the handling of loads in the form .5 of trailers by the use of U-formed, frame-formed supports comprising a horizontal beam and bearers in the form of legs which bear the aforementioned beam on an intended surface. Such trailer supports formed in this way require space to be available to the side. Space is often in short supply on board !0 ships, and because of the requirement to be able to load as much as possible in the interior of the ship, it is important for the load not to be unnecessarily bulky to the side. The same is also applicable to loading onto railway wagons, where it is even more important to take account of the width. Previously disclosed >5 earlier arrangements of this kind can be appreciated, for example, in SE 509 258C and PCT/SE02/02077. Supports in permanent locations are also provided on the deck on board ships and on railway wagons, although such arrangements require the load to be positioned at exactly the 30 same point on every occasion, and this can be difficult if different trailers are used. Manual guidance of the trailer to the intended parking position on board is then required, in addition to which lashing of the load is necessary. The principal object of the present invention is thus, in the first instance, to solve the aforementioned problems in a simple and reliable fashion. The aforementioned object is achieved by means of an arrangement in accordance with the present invention, which is characterized essentially in that the aforementioned beam and bearers are so arranged as to be capable of detachable attachment to one another, and in that the beam is so arranged, in conjunction with its movement by means of a load tractor vehicle, as to be connected to the same and thereby displaced together with separated from the aforementioned bearers. The invention is described below as a number of preferred illustrative embodiments, in conjunction with which reference is made to the accompanying drawings, in which Fig. 1 shows a cross-sectional view of a part of a load space on board a ship, which exhibits an arrangement in accordance with the invention performing its function of bearing a trailer on board a ship; Fig. 2 shows an enlarged view of a ringed area in Fig. 1; Fig. 3 shows a cross-sectional view of a larger area of a load space on board a ship with trailers borne therein in a supported loading position; Fig. 4 shows a cross-sectional view of a load space on board a railway wagon with a trailer supported therein; Fig. 4A shows a longitudinal view of lateral rails with a bearer accommodated therein; Figs. 5-7 are schematic representations of a the handling of a load support by means of a load tractor vehicle; Figs. 8-11 show the support in accordance with the invention in different views and sections; Figs. 12-15 are schematic representations of the guide and locking devices of the support viewed respectively in perspective and in section; Fig. 16 shows the support performing its function in conjunction with driving between lateral bearers set up on the deck for guiding and supporting a load; and Fig. 17 is a schematic representation of a locking latch for a beam. An arrangement 1 for supporting the front end 2 of a trailer 3 when parking the aforementioned trailer 3 on board ships 4, on railway wagons 5 and on other vehicles, comprising coupling means 6, 7 to permit the detachable attachment of the support 1 respectively to a trailer 3 of the kind in question and to a drivable loading tractor vehicle 8, is shown performing its function in the drawings in Fig. 6 and Fig. 16 respectively. The support consists of a beam 1 extending across a trailer 3 that is so arranged as to be borne at its respective ends 9, 10 raised for a distance H from the deck 11 or some other suitable parking surface by bearers 12, 13; 112, 113. In accordance with the invention, the aforementioned beam 1 and the bearers 12, 13; 112, 113 are so arranged as to be attached to one another in a detachable fashion. The beam 1 is also so arranged, in conjunction with its movement by means of a loading tractor vehicle 8, as to be connected to the aforementioned trailer 3 and thereby to be moved together separated from the aforementioned bearers 12, 13; 112, 113. In accordance with the invention, bearers are formed from permanent supporting strips 12, 13; 112, 113 or anchored lateral guide rails 212, 213 or similar bearers capable of being set up on the deck 11 that are situated to the sides of an intended trailer parking place 14, 114, 214 on ships 4, railway wagons 5 or some other vehicle of the kind in question. They are situated in this case at a lower level 130 than the level at which the beam 1 is present during driving on the ship 4, etc. In accordance with the embodiments illustrated in Figs. 1-4 and 12-15, the aforementioned supporting strips 12, 13; 112, 113 or the bearers 212, 213 are so arranged as to be supported by laterally situated walls 15, 115 on the ship 4, the railway wagon 5 or some other vehicle. They are formed in this case by rails in the walls 15, 115. Bearers can also be formed by outward-pivoting, telescopic or otherwise movable supports, which can be activated so as to support the beam 1 on desired occasions for stowage at the parking place. Arranged to act between the aforementioned supporting rails 12, 13; 112, 113 and bearers 212, 213, etc., and the beam 1 are lock fittings intended to hold the beam 1 in place in the intended stowage position I, CI, CCI on board, and the aforementioned lock fittings are preferably so arranged for this purpose as to be activated automatically by manoeuvring of the beam 1. It is possible in this way for stop heels 16 to be present on the under side of the beam 1, which heels are so arranged as to hold the beam 1, and thus the trailer 3, in position against forces which act in the transverse direction 17 of the ship, etc. The stop heels 16 are capable of being accommodated in congruent recesses 18, 218 in the aforementioned supporting strips 12, 13; 212, 213 or bearers 212, 213. Coupling means for the detachable attachment of supporting strips/bearers to a beam 1 are so arranged as to be displaced in a common direction from the principal longitudinal extent of the aforementioned beam. Bearers can be arranged for this purpose so that, after actuation, they are capable of being displaced to a position in which they support an aforementioned beam 1 and in which they are capable of being moved out of the way to the intended storage position. The aforementioned beams 1 are so arranged as to be capable of functioning as a means of guiding the trailer 3 when driving in the ship, etc., and along the same, in that the ends 19, 20 of the beams 1 or adjacent parts 21 each interact with their own rail 22, 23, 24; 122, 123 extending in the longitudinal extent of the aforementioned supporting strips or bearers. The function of the invention is as follows. The trailer support 1 is picked up by a tugmaster, etc., 8 from a magazine 24 on land 25. The trailer supports 1 are rowed up there one after the other and rest on supporting rails 26, 27 on both sides. The tugmaster 8 backs in and steers towards a trailer support 1 and locks this securely to its turntable 52 with a pin 6 on the under side of the support. The pin 6 is located under the turntable, which is secured to a vertically adjustable lifting arm. The tugmaster 8 then drives to a parked trailer 3, which is chocked up on its front folding legs 75, and backs in under the same at the same time as it steers with the trailer support's own turntable 52 against a pin 80, which is located under the trailer 3. When both the rearward-facing coupling 7 of the trailer support 1 and the aforementioned trailer pin 80 come into engagement with one another, they are locked securely, and the manual support 75 of the trailer is then folded out of the way. The entire team, comprising the tugmaster 8, the trailer support 1 and the trailer 3, then drives onto the ship 4, etc. The team is then driven by being backed in between guiding strips on the deck of the ship and supporting strips to both sides of it. Once the team has arrived in the intended stowage position I, the trailer 3 is lowered and the trailer support 1 is lowered with the vertically adjustable turntable on the tugmaster 8. The trailer support 1 is locked automatically in conjunction with this by means of lock fittings that are built in under the supporting rails as indicated above. The turntable of the tugmaster is then disconnected from the trailer support 1, and the tugmaster 8 returns to the trailer support magazine 24 to repeat the sequence outlined above. When unloading the trailers 3 from the ship 4, the procedure takes place in the opposite sequence from that described above. The trailer support 1 is used in the same way as described above to load railway wagons 5 that are intended to have a trailer driven onto them. A railway goods wagon 5 can consist of three parts in this case. The wheel arrangement, motor units and supporting and steering units for the central part of the wagon are housed in a front and a rear part of the wagon. The central part is recessed, and its carriageway lies between 200 and 300 mm above the rails on which the wagon runs. The central part is manoeuvred and rotated by the motor units causing it to adopt a position such that flaps on the central part can be folded outwards and down onto the ground. Loading of the goods wagon then starts as described above. In order to keep the beam 1 securely in place in the intended stowing position, the side rails or bearers exhibit guide rails that are closed both in a direct downwards 500 and in a direction upwards 501. In order to facilitate guiding the beam 1 into the guide rail, this exhibits a divergent guiding part 300, 301 at least at one of its ends. In order to keep the beam in place in a side rail or bearer, a latch 100 is provided which is capable of being actuated by the loading tractor vehicle 8 and is so arranged, when in the position in which it is disconnected from the vehicle 8, as to interact with a part 101 in a recess 102 on the aforementioned side rail or bearer. The latch 100 is spring-assisted in order to guide the latch part 101 into latched engagement and is formed by an arm that is pivotally mounted on the beam 1, the opposite end 103 of which arm is capable of being actuated by a part of the vehicle 8. Another alternative means of locking involves incorporating hydraulically actuated hooks in the bearers and/or side rails, which lock the trailer beam from the bottom up. The invention is naturally not restricted to the embodiments described above and illustrated in the accompanying drawings. Modifications are possible, in particular with regard to the nature of the various parts, or by the use of equivalent technology, but without departing from the area of protection afforded to the invention, as defined in the Patent Claims.