WO2007049067A1

WO2007049067A1 - Landing leg

Info

Publication number: WO2007049067A1
Application number: PCT/GB2006/004047
Authority: WO
Inventors: James Edwin Jemison
Original assignee: O.S.D.A.L. Limited
Priority date: 2005-10-28
Filing date: 2006-10-27
Publication date: 2007-05-03
Also published as: GB0522001D0

Abstract

A trailer landing leg (40) comprises an upper leg portion (42) and a lower leg portion (44) telescopically mounted with respect thereto, in which the lower leg portion (44) is carried by a support means (4) arranged to allow the lower leg portion (44) to move between a raised storage position and a lowered in-use position, the landing leg (40) further including a locking means operable to lock the lower leg portion (44) relative to the upper leg portion (42). The locking means described provides a convenient and secure way of locking the lower leg portion (44) in position.

Description

Landing Leg

This invention relates to landing legs, for use particularly, but not exclusively, with articulated trailer units.

Landing legs are used to support the front portion of a trailer when it is uncoupled from a tractor unit. Known landing legs comprise a fixed upper leg portion, from which a lower leg portion can be extended telescopically for use. The lower leg portion is typically mounted on a geared shaft, which is operated by a large hand operated winding handle.

These known landing legs suffer from a number of drawbacks. Firstly, it can require considerable physical effort to operate the winding handle to lower and raise the lower leg portion. The operator, who is often the tractor driver, must turn the winding handle until the lower leg portion is sufficiently lowered or raised, which requires considerable physical effort. Also, as the lower leg portion can be lowered to any position within its range of movement, there can be differences in the height at which parked trailers are set . This can lead to problems if the trailers are set too low or too high for particular tractor units, with the result that trailers may have to be raised or lowered by hand using the landing leg.

Other landing legs have been described employing alternative means for moving the landing legs, for example US 5,509,687 describes the use of an air bladder and return spring for controlling the movement of a lower leg portion in an upper leg portion. However, the landing leg described in US 5,509,687 and other similar landing legs require a relatively complex safely latch and lock mechanism for fixing the lower leg in position relative to the upper leg portion.

The present invention is intended to address one or more of the above problems, or other related problems associated with the prior art not mentioned above.

According to the present invention there is provided an apparatus and method as set forth in the appended claims . Preferred features of the invention will be apparent from the dependent claims, and the description which follows.

For a better understanding of the invention, and to show how embodiments of the same may be carried, into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

Figure 1 is a schematic side sectional view of a landing leg according to an exemplary embodiment of the invention, in an in-use position;

Figure 2A is a schematic front view of a pair of landing legs of Figure 1 in use with a trailer;

Figures 2B-2E show schematic front sectional views of a leg according to another exemplary embodiment of the invention, featuring latching means; Figure 3 shows a side sectional view of upper and lower landing leg portions having a wedge arrangement therebetween_/

Figures 4A and 4B show side schematic views of pin actuators for use with the landing leg of Figure 1 or 2, having pin position indicators;

Figure 5 shows a side view of a pin and pin end cap; and

Figure 6 shows a side view of an alternative pin.

Referring now to Figures 1 and 2 , an embodiment of the landing leg 40 is shown. The leg 40 comprises an upper leg portion 42, a lower leg portion 44 telescopically mounted therein, an actuator 56 and a foot 54. The upper and lower leg portions 42,44 comprise lengths of hollow box section material such as steel. The lower leg portion 44 is carried by support means 4 adapted to allow the lower leg portion 44 to move, preferably to drop by means of its own weight, from a raised storage position to an in-use position, as described below. Locking means can be used to lock the lower leg portion 44 in position relative to the upper leg portion 42 in the in-use position, and the support means 4 is adapted to raise the lower leg portion 3 from said in-use position into said storage position, as also described below.

A top cap 46 covers the top of the upper leg portion 42. A bottom cap 48 covers the bottom end of the lower leg portion 44. An actuator mounting bracket 50 is located within the upper leg portion 42. A slot 52 is located part way up the length of the lower leg portion 44. A rocking foot 54 is connected to the bottom of the lower leg portion 44 via the bottom cap 48. The lower leg portion 44 is provided with a slot 65 in the form of a through aperture. The slot 65 is defined by aligned apertures in opposed walls of the box section material forming the lower leg portion 44. The slot 65 may

'comprise an interior portion with a tube-like wall structure running between the aligned apertures.

The upper leg portion 42 is similarly provided with a slot 62 defined by aligned apertures in opposing' walls of the box section material forming the upper leg, portion. - The apertures 62,65 are sized to receive a movable pin 95 therethrough. The pin is carried by a pneumatically operated actuator. Operation of the; pin _.95 will be described in greater detail below. The upper end 45 of the lower leg portion 44 is provided with a, pad 47 of high friction material such as a rubber material.

The actuator 56 is of the pneumatic type and comprises a body 58 and rod 60. Suitable actuators are available from the multinational ASCO Joucomatic group of companies. The rod 60 has a ball-type end 63 although it will be appreciated that other arrangements such as, for example, threaded connections may be employed to connect the rod to the lower leg portion 44. The body 58 of the actuator 56 is housed between part of the wall 64 of the upper leg portion 42 and the bracket 50 located part way up the length of the upper leg portion 42.

The landing leg 40 extends and retracts in the directions indicated by arrow 81. When the landing leg 40 is fully retracted, the rod 60 is positioned largely within the body 58 of the actuator 56 and the lower leg portion 44 is fully retracted into the upper leg portion 42. When the landing leg 40 is fully extended, as shown in Figure 2, the rod 60 extends out of the body 58 of the actuator 56 and the lower leg portion 44 and upper leg portion 42 are spaced apart at a defined distance relative to each other.

In the fully retracted position, the pin 95 is positioned through the pin slots 62,65 of the upper and lower leg portions 42,44 to lock the upper and lower leg portions 42,44 together telescopically within each other.

To move the landing leg from the fully retracted position to the fully extended position, the pin 95 is removed from the pin slots 62,64 of the upper and lower leg portions 42,44 the lower leg portion 44 is allowed to. drop downwards ■ either by gravity or by the actuator 56 extending the rod 60. When the lower leg portion 44 has dropped to produce full extension of the landing leg 40, the pin 95 is replaced into the pin slots 62 of the upper leg portion 42.

In a position close to the fully extended position, the upper end 45 and high friction pad 47 of the lower leg portion 44 comes into contact with the pin 95, and the pin 95 prevents the landing leg 40 retracting. It will be understood that, in use, the landing leg 40 in this extended position bears the weight of a trailer, and hence the pad 47 is urged against the pin 95. The high friction nature of the pad material thus resists the removal of the pin when the landing leg 40 is in a weight bearing condition. By choosing to have the pin 95 bear against the upper portion 45 of the lower leg portion 44 the construction of the lower leg portion 44 is considerably simplified. Furthermore, the fact that the pin 95 can be extended through the upper leg portion 42 when the lower leg portion 44 has dropped past the pin's position means that there is no need for a complicated or precise alignment of lower leg and upper leg portions 44,42 when the landing leg 40 is to be locked in the in-use position. It is sufficient for the uppermost portion of the lower leg portion 44 to pass the pin 95.

To move the lower leg portion 44from the in-use position to the fully retracted position, the pin 95 is removed from the pin slots 62 of the upper leg portion 42, and the lower leg portion 44 is raised, for example by retracting the rod 60, or by manually lifting. When the lower leg portion 44 has risen to the point of full retraction of the landing leg 40, the pin 95 is replaced into the slots 62,65 of the upper and lower leg portions 42,44 to fix the upper leg portion 42 and lower leg portion 44 together in the raised storage position.

To remove the pin 95 the upper leg portion 42 must be raised by a small distance (e.g. 20mm) relative to the lower leg portion 44 to create a small gap between the pin 95 and the pad 47 of the lower leg portion 44 therefore allowing the pin 95 to be more easily removed from the pin slots 62. Methods for raising the landing leg upper portion 42 include raising the whole trailer to which the landing leg is attached, for example by inflating air bags connected to a tractor unit which tows the trailer.

It will be appreciated that the above described landing leg differs from known arrangements in that it cannot be used to raise the trailer, because there is no load bearing connection between the lower leg portion 44 and the trailer chassis. The actuator 56 is only sufficiently powerful to move the lower leg portion 44, rather then being sufficiently powerful to raise the trailer to which it is attached.

In an alternative embodiment, shown in Figure 2E, the pin 95 and the upper end portion 45 of the lower leg portion 44 may be provided with a first latching means to resist the removal of the pin when the landing leg 40 is in a weight bearing condition. Such latching means may suitably comprise a latching feature such as a projection on one of the pin 95 and upper end portion 45 of the lower leg portion 44, and a latching feature such as a recess on the other of the pin 95 and upper end portion 45 of the lower leg portion 44. Suitably, the latching means comprises a recess in the pin 95, and a projection on the upper end portion 45 of the lower leg portion 44. The recess may suitably comprise an annular groove 10 running around the circumference of the pin 95, and the projection 11 may suitably comprise a substantially linear projection of complementary cross section to that of the groove 10.

The first latching means in use provides a mechanical interface between pin 95 and lower leg portion 44 to ensure that the pin 95 can not be removed when the landing leg 40 is weight bearing. To remove the pin 95, the upper leg portion 42 is raised by a small distance to disengage the projection 11 and groove 10 to create a small gap therebetween. The pin 95 can then easily removed from the pin slots 62. Methods for raising the landing leg upper portion 42, as described above include raising the whole trailer for example by inflating air bags connected to the tractor unit which tows the trailer.

The pin 95 and an interior portion of the slot 65 may comprise a second latching means to resist the removal of the pin 95 when the landing leg 40 is in the storage position.

Such latching means may suitably comprise a latching feature such as a projection 12 mounted on one of the pin 95 and the interior portion of the slot 65, and a latching feature such as a recess mounted on the other of the pin 95 and the interior portion of the slot 65. Suitably, the latching means comprises a recess in the pin 95, and a projection 12 on the interior portion of the slot 65. The recess may suitably comprise an annular groove 10 running around the circumference of the pin 95, and the projection may suitably comprise a substantially linear projection 12 of complementary cross section to that of the groove 10.

The second latching means in use provides a mechanical interface between pin 95 and lower leg portion 44 to ensure that the pin 95 can not easily be removed when the landing leg 40 is locked in the storage position. To remove the pin 95, the lower leg portion 44 is raised by a small distance to disengage the projection and recess to create a small gap therebetween. The pin 95 can then easily removed from the pin slots 62. Methods for raising the lower leg portion 44, as described above include using the actuator 56, or manual raising.

In particularly preferred embodiments, a single latching feature on the pin 95 can be used in the first and second latching means. For example the an annular groove 10 on the pin may engage on a latching projection 11 on the upper portion 45 of the lower leg portion 44, and may also engage a latching projection 12 on an interior portion of 5 the slot 65. Figures 2B-2E show such an arrangement, with a pin 95 comprising a pair of annular grooves 10, and complementary projections 11,12 in the slot and on the upper portion 45 of the lower leg portion 44. Also shown in Figures 2B-2E is ground level 1. 10

In Figure 2B the lower leg portion is fully retracted, allowing the pin 95 free movement in the slot 62.

In Figure 2C an interior portion of the slot 65 of the 15. ^'lower leg portion 44 is resting on an _/upper part of the pin 95, and the second latching means inhibits removal of the pin 95 from the slots 65,62.

In Figure 2D the lower leg portion 44 is fully extended, 20 allowing free movement of the pin 95 over the upper portion 45 of the lower leg portion 44.

In Figure 2E the upper portion 45 of the lower leg portion 44 is resting on a lower part of the pin 95, and the first 25 latching means inhibits removal of the pin 95 from the slot 62.

In a preferred embodiment the actuator for the pin 95 is controlled independently from the actuator 56 for the leg 30 portions 42,44. In the raised position, the lower leg portion 44 is telescopically mounted within the upper leg portion 42 and the pin 95 located between the pin slots 62,65 of the upper and lower leg portions 42,44 prevents the lower leg portion 44 from moving downwards to bring the landing leg 40 into an extended position.

To move the landing leg 40 from a raised position to an in use position, firstly the lower leg portion 44 is raised slightly relative to the upper leg portion 44, for example by a few mm, to remove the weight if the lower leg portion 44 from the pin 95 by moving a switch A (Figure 2A) from an 'off position to an 'on' position. Secondly, the pin 95 is removed from the pin slots 62,64 of the upper and lower leg portions 42,44 by moving a switch B (Figure 2A) from an 'off' position to an 'on¹ position. In a preferred embodiment it is not possible to remove the pin 95 until the upper leg portion 42 has been raised slightly. In a preferred embodiment, one or more of the switches is spring-loaded to urge the switches towards the •off position. Following removal of the pin 95, the lower leg portion 44 may drop by gravity or be lowered by the actuator 56.

When the landing leg 40 is fully extended, the pin 95 is replaced in position between the pin slots 62 of the upper leg portions 42 to prevent the landing leg from retracting.

Replacement of the pin 95 may be achieved by moving switch B from the 'on' position to the 'off' position. Alternatively, or in addition, replacement of the pin may be achieved by a spring urging the pin to locate in the pin slots 62 of the upper leg portions 42.

To move the leg from the in-house position to the raised position, the upper leg portion 42 is first raised relative to the lower leg portion 44 and then the steps outlined above are carried out in reverse order. The upper leg portion 42 may be raised by raising the trailer unit e.g. by inflating airbags connected to a tractor unit attached to the trailer.

In a preferred embodiment, the landing leg has a square cross section with each side of the upper leg portion being 140mm wide. In this preferred embodiment the landing leg is constructed from material which is 5mm thick. The height of the landing leg can be varied to suit the trailer unit to which it is to be attached. Also, the area around the pin slots may be reinforced by thicker material, or by an additional bushing or like structure .

It should be noted that, alternatively, the- actuator may be positioned in the lower leg portion 44. In this case, the components previously described as being associated with the upper leg portion 42 would now be associated with the lower leg portion 44 and vice versa except the rocking foot 54 which cannot be usefully positioned on the upper leg portion 42.

Referring to Figure 2A, there is shown an arrangement for a trailer having two landing legs 40. Each landing leg 40 comprises an upper leg portion 42, a lower leg portion 44 telescopically mounted therein and an internal actuator 56. In contrast with the landing leg of Figure 1, the landing leg of Figure 2 has a static foot 86 instead of a rocking foot. The foot 86 is provided with a protective coating 80 such as, for example, a thick layer of rubber- like material. The coating 80 serves to protect the foot 86 from corrosion, and to improve grip when the landing leg 40 is deployed.

The landing legs 40 extend and retract in the directions indicated by arrow 81.

The landing legs 40 are mounted to a trailer 88 by brackets 90. The landing legs 80 are further connected to each other by a cross-rail 92 which is substantially perpendicular to the landing legs 80. Pin release actuators 94, are mounted on the cross-bar 92. The actuators 94 are activated remotely via a control box 100. Each actuator includes a pin 95 which is movable towards and away from the landing legs 40 as indicated by arrows 82.

In a preferred embodiment, as a safety precaution, a key operated lock 96 is mounted on the exterior of a landing leg to prevent removal of the pin. This allows the landing leg to be locked in the extended position to reduce the risk of the landing leg being raised by a remote operator without the knowledge and/or consent of an authorised operator, for example a driver.

In a preferred embodiment, the key operated lock 96 engages with the pin 95 to prevent the pin 95 from being removed from the pin slots in the upper portion 42 of the landing leg.

A pneumatic control system for the operation of the landing leg and pin release actuators 56,94 is shown in Figure 5. The control system comprises a control box 100 having operation buttons or switches A and B which are operable in the manner described above to drive the actuators 56,94. The box 100 may be provided with locking means to prevent unauthorised operation of the switches A, B. The box 100 is provided with a connection line 102 to a source of pressurised air. Typically the source is provided by the tractor unit to which the trailer may be connected. Preferably the connection line 102 is fed by the red line coil supply of the tractor unit. The connection line 102 further includes a spur 104 having a valve. The spur 104 is provided so that an external pressure supply can be connected to the control system.

Extending from the control box 100 there are provided a plurality of feed lines 106, 108, 110 which connect the control box to the actuators 56,94. In the embodiment shown the pin actuators 94 are double acting and hence are provided with two feed lines 106,108, while the leg actuators 56 are single acting and thus provided with a single feed line 110. It will be appreciated that in the case of the leg actuators being double acting, then a further feed line would be provided. The control box 100 is preferably provided on the trailer in the vicinity of the landing legs 40, for example on a chassis leg of the trailer. Optionally, the trailer may be provided with an additional control box. The additional control box may be situated adjacent to the offside front marker lamp of the trailer.

Referring now to Figure 3 , there is shown a cross sectional view of a landing leg 40 having upper and lower leg portions 42,44. The interior walls of the upper leg portion 42 are provided with a tapered inserts 112, while the lower leg portion 44 is provided with a cap 114 having a correspondingly tapered fore portion 116. In use, lowering or dropping of the lower leg portion 44 relative to the upper leg portion 42 causes the tapered portions of the inserts 112 and cap 114 to contact one another. The tapered portions thus act to arrest the downward movement of the lower leg portion 44 and thus prevent excess loads being experienced by the leg actuator 56.

Figures 4A and 4B respectively show a pin 95 of a pin release actuator 94 in an engaged and a disengaged position relative to an upper leg portion 42 of a landing leg. The pin 95 is provided with an indicator 118 comprising a stalk 120 having a bulbous end 122. The end 122 is preferably coloured so as to be highly visible. As such, an operator can readily ascertain whether or not the pins 95 are in the engaged or disengaged positions. . In the event of a failure of the pneumatic supply to the actuator 94, the indicators 118 may be used as handles to manually move the pins 95.

Figure 5 shows a pin end cap generally designated 124. The cap 124 comprises a head 126 and a stem 128. The stem 128 is of a smaller diameter than the head 126 and is sized so as to fit to an end aperture 130 of a pin 95. The pin 95 is shown projecting from an upper leg portion 42 of a landing leg. The stem 128 is provided with a plurality of detents 132 comprising captive sprung spherical members. The pin aperture 130 is provided with complimentary recesses 134. The head 126 has a diameter greater than that of both the pin 95 and aperture 62 in the upper leg portion 42 through which the pin 95 extends. The cap 124 is connected to the upper leg portion 42 via a length of chain, cable or wire 136. The cap 124 may be fitted to the pin 95 to give an indication that the pin 95 has extended fully through the upper leg portion 42. To assist in giving such an indication, the head 126 may be brightly coloured. Upon withdrawal of the pin 95 from the upper leg portion 62, the head 126 contacts the upper leg portion and the cap 124 may be provided with a locking means to prevent disengagement of the cap 124 in this manner. For example, the cap 124 and pin 95 may be provided with complimentarily form locking features. ^' In such an embodiment the stem 128 of the cap 124 may be required .to be inserted onto the pin aperture 130 and rotated, through a desired angle to lock the cap 124 to the pin 95. Alternatively a lock mechanism requiring a. key may be incorporated into one of the pin 95 or cap 124 > .

Figure 6 shows an alternative embodiment of the pin 95, provided with an annular groove 91 running around its circumference. The groove 97 can receive a secondary retaining device su'ch as an R-clip, U-clip or the like. A key operated lock can be used to secure the secondary retaining device in place in the groove 97, as a simple means for securing the pin 95 in place when fully through the upper leg portion 42. The secondary retaining device and the key operated lock may conveniently be tethered to the upper leg portion 42 to prevent their' unauthorised removal, or accidental loss.

Other features may be incorporated into the landing legs of the present inventions. For example, the actuators of the pneumatically operated embodiment may be, provided with whistle means operable by compressed air supplied to the actuators. In such an embodiment, exhaust air from the actuators may be supplied to the whistle means at each end of the actuator's travel to give an audible indication that the actuator has moved to its full extent, or alternatively exhaust air may be used with whistle means to give an audible indication that the actuator has not yet moved to its full extent.

In one alternative embodiment (now shown) the pneumatic actuator may be replaced with another suitable mechanism which is powered by a power source on an associated tractor unit. It will be appreciated that other parts of the landing leg described above could also be automated in other embodiments .

In other alternative embodiments (not shown) the lower leg portion, or any part of the support means, is damped such that when the lower leg portion drops under its own weight it does not do so in a sudden or violent way.

In another alternative embodiment (not shown) the landing leg is provided with a greater width, such that it takes the form of a box which extends from one side of a trailer to the other, such that only one landing leg is required to support the trailer, and not two. In any of the embodiments the upper leg portion may comprise an outer box section and the lower leg portion may comprise an inner box section. Alternatively, the upper leg portion may comprise an inner box section and the lower leg portion may comprise an outer box section.

While the above described embodiments of the invention have been described with reference to demountable articulated trailers, it will be appreciated that the invention may be utilised in connection with other trailer types including draw-bar trailers. Legs of the type described may also be utilised as stabilisers for tanker type trailers and tipping trailers.

The inner of the leg portions may be provided with a visible indicator or marker which is revealed as the lower leg portion extends and becomes hidden when the lower leg portion is retracted. The degree to which the indicator or marker is visible gives an easily interpreted indication as to the extension state of the landing leg.

The above described embodiment has a number of advantages over the prior art. First of all, the landing leg can be deployed swiftly arid easily in a so-called "drop and lock" method, as there is no need to physically unwind the lower leg portion as with known devices. This saves time and physical effort.

Further, the landing leg can be lowered and raised without the need for a large winding handle of the known type. The landing leg can be deployed by simply moving the locking pin 95. Known modern tractor units can carry the load of the trailer during this process, and can raise and lower the trailer to allow the locking ^• means to be deployed as described above. The invention also includes a method of using the landing leg described above with a tractor unit which has the capacity to raise and lower its coupling device. Known mechanisms provided in tractor units to raise and lower trailer include hydraulic or pneumatic suspension which can raise and lower the height of the whole tractor unit chassis on its wheels, and airbags which are used to raise and lower a trailer coupling apparatus of the tractor unit.

The landing leg can be lowered into only one in-use positions. This means that trailers with the landing leg will always be parked at one chosen height in particular. This makes coupling tractor units to parked trailers far easier, and reduces the problems associated with known devices which can support trailers at any height.

Furthermore, the locking means described is of simple construction, yet is safe, reliable and can be easily incorporated into an automated system.

Thus a novel landing leg is provided which solves a number of problems associated with known landing legs.

Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification

(including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

Claims :

1. A trailer landing leg comprising an upper leg portion and a lower leg portion telescopically mounted therein, in which the lower leg portion is carried by support means adapted to allow the lower leg portion to move from a raised storage position to an in-use position, the landing leg further comprising locking means operable to lock the lower leg portion relative to the upper leg portion in the in-use position by abutting an upper portion of the lower leg.

2. The trailer landing leg of claim 1, wherein the locking means comprises a locking pin operable pass through a locking pin slot in the upper leg portion, and to abut the upper portion of the lower leg to lock the lower leg portion with the lower leg portion^' in the in-use position.

3. The trailer landing leg of claim 2, wherein the locking pin extends through the locking pin slot of the upper leg portion and across the interior of . the upper leg portion thereby defining a bearing surface which the upper end of the lower leg portion abuts when the lower leg portion is in the in-use position.

4. The trailer landing leg of claim 2 or 3, wherein a second locking pin slot is provided at a bottom of the lower leg portion which can align with the slots at the bottom of the upper leg portion when the lower leg portion is in the storage position, such that the locking pin can be passed therethrough to lock the lower leg portion in the storage position.

5. The trailer landing leg of claim 2, 3 or 4, wherein the locking pin is moveable into and out .of the slots along a path which is substantially transverse to the telescopic arrangement of the leg portions .

6. The trailer landing leg of any one of claims 2-5, wherein the locking pin is mounted to an actuator operable to move the pin between an extended position where the pin is engaged in the pin slots and a retracted position where the pin is not engaged in the pin slots.

7. The trailer landing leg of any one of claims 2-6, wherein the locking pin comprises part of a latching means, and one or both of the upper portion of the lower leg and the locking pin slot of the lower leg comprise another part of the latching means. ^■ •

8. The trailer landing leg of claim 7, wherein the part of the locking pin which comprises the latching means is a recess and the part of the upper portion of the lower leg and/or the locking pin slot of the lower leg which comprise the other part of the latching means comprises a projection.

9. The trailer landing leg of claim 8, wherein the part of the upper portion of the lower leg and the locking pin slot of the lower leg which comprise the other part of the latching means both comprise a projection, and the part of the locking pin which comprises part of the locking means is arranged to latch with both the other parts of the latching means .

10. A method of using a tractor unit provided with trailer coupling apparatus and mechanical lifting means adapted to raise or lower the trailer coupling apparatus, and a trailer unit provided with a trailer landing leg according to any one of claims 1-9, the method including the following steps of:

(a) mounting the trailer on the trailer coupling apparatus ;

(b) arranging the trailer into a parked position;

(c) lowering the lower leg portion into the in-use position; and

(d) if required, operating the mechanical lifting means to raise or lower the trailer coupling apparatus to allow the lower leg portion to assume the in-use postition; and

(e) Locking the lower leg portion into the in-use position.

11. The method of claim 10, further comprising removing the tractor unit from the trailer.

12. A trailer provided with one or two landing legs, each landing leg as claimed in any one of claims 1-9.