WO2012056242A1

WO2012056242A1 - Trailer landing leg and vehicle

Info

Publication number: WO2012056242A1
Application number: PCT/GB2011/052098
Authority: WO
Inventors: Mandy Jean Miller; James Edwin Jemison
Original assignee: Autoneumatics Limited
Priority date: 2010-10-28
Filing date: 2011-10-28
Publication date: 2012-05-03
Also published as: GB201018192D0

Abstract

A vehicle landing leg comprising upper and lower portions telescopically fitting together for movement between an extended state in which when fitted to a vehicle the lower portion makes ground contact and a retracted state in which when fitted to a vehicle the lower portion is above ground. Actuating is provided means for effecting movement of the lower portion between extended and retracted states and in embodiments is a first pneumatic ram. Latching means is pivotally secured to the upper portion and is engageable through an opening in the upper portion with the top of the lower portion to maintain the leg in its extended state and with a keep located towards the lower end of the lower portion to maintain the leg in its retracted state. A second pneumatic ram having a line of action generally parallel to that of the leg is provided for movement of the latching means between engaged and released states. A pair of the legs may be fitted to a semi-trailer vehicle and that vehicle may be coupled to an air suspension which can lift or lower the front of the semi-trailer to adjust the height of a front end thereof.

Description

TRAILER LANDING LEG AND VEHICLE

FIELD OF THE INVENTION The present invention relates to trailer landing legs for attachment to semitrailers, drawbar trailers and the like, to semi-trailer and drawbar trailer vehicles fitted with the landing legs, to demountable shipping containers fitted with landing legs and to tractor-trailer combinations fitted with the landing legs, e.g. those in which the tractor is fitted with an air suspension.

BACKGROUND TO THE INVENTION

Landing legs are known and are used to support the front portion or the rear portion of a trailer when it is uncoupled from a tractor unit. Generally, the most common type comprises a fixed upper leg portion from which, in use, a lower leg portion can be telescopically extended. The lower leg portion is typically mounted on a geared screw shaft, which is operated by a large hand operated winding handle. The handle is rotated in one direction to raise the lower leg portions into the upper leg portions, or the handle is rotated in the opposite direction to lower the lower leg portions to a fully extended position, ready to support a loaded trailer once it has uncoupled from the tractor. The aim is to adjust the trailer height by winding the handle in one direction or another thereby adjusting the height of the trailer, so that a tractor unit can fit underneath the trailer and engage it. The need to adjust the height arose because historically, most tractor units used leaf spring suspensions systems which could not adjust their coupling height.

Tractors for semi-trailers incorporate a coupling device known as a 'fifth wheel' which fits under and grips a depending king pin at the front of the trailer to couple the tractor and trailer together while permitting articulation between them. Modern tractor units now incorporate air suspension which permits the height of at least the rear part of the tractor vehicle incorporating in the case of a semi-trailer the fifth wheel to be raised or lowered by increasing or decreasing the pressure within the suspension airbags. When the tractor and trailer are coupled together the front of the trailer can be raised or lowered relative to the ground by raising or lowering the fifth wheel using the air suspension. When a trailer is being supported by landing legs, and it is desirable to mount it to a tractor, then once the tractor unit is under the trailer, then by pressing buttons within the cabin of the tractor, it is possible to adjust the tractor coupling height by inflating the "airbags" on the suspension system to match the tractor and trailer heights. Once the trailer has been connected to the tractor, the load is transferred from the landing legs to the tractor fifth wheel coupling apparatus, which then enables the landing legs to dangle off the ground. This is then followed by winding the handle safely to raise the legs back to their retracted position. However, considerable effort is needed.

There are many practical difficulties with arrangements of this type. The operator, who is usually a tractor driver must mount the winding handle and operate it until the landing leg is sufficiently raised or lowered. This can result in joint or back injuries, especially so if a handle inadvertently gets worn or defective. A further difficulty is that the winding handle requires storage space in the trailer and needs space at the side of the trailer for the driver to operate it. If a number of trailers are parked side by side, for example for safe storage or while unloading cargo, then large gaps must be left between them to allow for the operation of the winding handles. In addition, as the lower leg portion can be lowered to any position, there can be considerable differences in the height at which parked trailers are set. This can lead to problems when the trailer is left too high or too low by different tractor units, with the result that the trailer may then have to be raised or lowered by operating the winding handle, without the help of a tractor's fifth wheel apparatus. Likewise this can cause back injuries and multi- skeletal disorders from the over-exertion of winding.

Another problem with the above conventional landing legs is that airbags of a tractor may deflate overnight due to natural leakage. The normal procedure before uncoupling the tractor unit from the trailer is to release the air from the air suspension, followed by lowering the landing legs fully, before disconnecting the supply coils and fifth wheel jaws, so that the trailer is supported by the landing legs and the axles. If the trailer airbags are left inflated, after the tractor has uncoupled, the natural leakages will cause the airbags to deflate, which in turn will cause the landing leg rocking feet to begin to lurch because of the load stress passing through the trailer chassis. If this happens, then the back end of the rocking feet will slowly move all the way to the lower leg portions, digging into the lower leg portions, which causes damage to the steel box tubes. This damage will prevent the normal operation of the telescopic arrangement of the leg portion such that, the lower leg portion will be unable to be retracted up fully into the upper leg portion, with the result that when a trailer is coupled onto the tractor, the landing legs are taken onto the roadways only partially retracted, which may cause damage to the road surfaces since the legs would be hanging considerably close to the road surface.

A further problem that exists with traditional hand-wound devices is that the trailer often is fitted with two different types of legs. One leg is fitted with a gearbox, used to rotate the bevel gears to rotate the screw. This is known as a drive leg. The other leg is known as the slave leg, which moves up or down via a crossbar connected from the drive leg. In the event of failure of one of the legs, it becomes very difficult to move the legs individually, with the result that the landing legs would need to be removed from the trailer for repair. This is also important because in replacing damaged conventional landing legs, it is currently not possible to order a single landing leg, instead a buyer is required to order both a drive leg as well as a slave leg, which becomes costly for owners of large fleets.

Various arrangements have been tried to improve the utility and convenience of landing legs, but none has so far been successful and landing legs based on screw jacks continue to predominate.

Conventional telescopic landing gear has driver and slave legs connected by a crossbar, and in the Jost Easydrive modular leg an electric motor rotates the crossbar. However, electric motors in this environment are difficult to maintain and are prone to failure. US 7036847 (Jost-Werke) exemplifies an arrangement of this type.

A product known as Auto-Legs and built by CHK pic. of Crewe, Cheshire, UK has a lower leg portion that swings pivotally back relative to the trailer chassis for a road-going journey. However most trailers require modification before legs of this type can be fitted, and if the air supply fails there is a risk of the legs returning into contact with the road while the vehicle is travelling. In a further arrangement of this general kind, GB 1355194 discloses a landing leg that comprises two support legs fixedly mounted on a shaft that is pivotably mounted on the front of the semi-trailer and means, in the form of a pneumatic lifting cylinders that are connected by levers to the shaft, for rearward pivoting the legs from a ground engaging position in a rest position. It has tension springs connected to the shaft by levers for pivoting the legs to their support position and a vertically displaceable fifth wheel, for raising the front of the semi-trailer to enable movement of the legs between the said positions when relieved of the semitrailer weight. A locking device secures each leg in its ground engaging position and is un-lockable by a respective piston and cylinder The device is operated by a pneumatic circuit for controlling the cylinders that is connectible to a compressed air source of the tractor, operable when the trailer is coupled thereto.

US5409251A discloses a landing gear assembly for use in supporting a semitrailer. It has a body and a leg axially extensible from the main body. An expansible membrane disposed within the main body is provided for displacing the leg to an extended position. A restrictive passage through the main body limits the travel of the leg through the main body. Upon compressing the expansible membrane, a biasing element disposed within the main body is provided for urging the leg back to a retracted position. The leg may be releasably secured in either an extended or retracted position.

US5509687 discloses the use of an air bladder and return spring for controlling the movement of a lower leg portion. It has a safety latch and lock mechanism that connects the lower leg in position relative to the upper leg portion.

An earlier prototype version of our Easylegs product uses a locking pin and pneumatic actuator to lock and unlock the locking pin which moves along a path that is substantially transverse to the telescopic arrangement. It has a cross rail that is used to mount the locking means actuator in order to move the locking pin to the unlock position. The locking pin arrangement is strong and sturdy. However, this type of landing leg is awkward to fit to some types of trailer, most notably draw bar trailers that have restrictive mounting positions or narrow chassis beams.

Devices described in these disclosures are not ideally suited to supporting trailers for a number of reasons. Accordingly, it would be desirable to have a trailer landing leg system that can overcome one or more of the disadvantages and limitations described above and provides a more effective alternative that is economical to manufacture, affordable to purchase, safe to use and user-friendly. SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a landing leg comprising:

a first member telescopically disposable adjacent a second member;

at least one actuator operably connectable between said first and second members;

the landing leg being further provided with a locking means pivotably disposable adjacent the or a portion of the first member means; and activation means operable to effect movement of the second member means relative to the first member means, wherein said activation means is adapted to operate said locking means to immovably lock the second member means.

In a second aspect the invention provides a vehicle landing leg comprising:

upper and lower portions telescopically fitting together for movement between an extended state in which when fitted to a vehicle the lower portion makes ground contact and a retracted state in which when fitted to a vehicle the lower portion is above ground;

actuating means for effecting movement of the lower portion between extended and retracted states;

and latching means pivotally secured to the upper portion and engageable through an opening in the upper portion with the top of the lower portion to maintain the leg in its extended state and with a keep located towards the lower end of the lower portion to maintain the leg in its retracted state.

In a third aspect the invention provides a trailer vehicle having a body fitted with at least one leg as defined above, more usually at least one pair of legs. In the latter case the legs of the pair may be connected at a single junction box to a common fluid supply and control system for simultaneous movement between extended and retracted positions and for simultaneous engagement and disengagement of the latching means. The vehicle may be a drawbar trailer or a semi-trailer. In an alternative aspect the invention provides a demountable shipping container for carriage on a vehicle having legs on which the container can stand when the container is demounted, the legs being as defined above. The invention further provides a rig comprising a tractor and a trailer vehicle coupled thereto the trailer vehicle having legs as defined above. The rig may employ a tractor having a pneumatic suspension or less preferably a leaf spring suspension. Pneumatic suspension may be adjustable to lift and lower the front of the trailer portion and air supply of the tractor may be connected to a fluid supply and control system for the leg or legs. The invention further provides a rig comprising a vehicle having a chassis on which a demountable shipping container having legs as defined above is carried.

According to a further aspect of the present invention, there is provided a method of using trailer landing legs comprising providing a trailer leg apparatus as described above, the method including the steps of; mounting the trailer onto the tractor coupling apparatus, arranging the trailer into a parked position, lowering the lower leg portions of the landing legs into the extended position, locking the lower leg portion into the extended position, if required, operating the tractor's coupling apparatus to raise or lower the trailer to enable the lower leg portion to support the trailer and uncoupling the tractor from the trailer.

The present system comprises air-powered trailer "landing" legs, which are used to replace existing manually operated legs. The landing legs prop up an unconnected trailer, but without the requirements for physical human effort to lower and raise legs when parking or taking away a trailer. The present system in some embodiments employs the existing pressurized tractor air supply to lift or lower and lock the legs into the raised or lowered position. The legs do not lift and lower the trailer, they simply act as props to support a freestanding trailer, and thus the actuating forces involved are kept to a minimum. The lifting and lowering of the trailer may be accomplished in embodiments by employing the tractor-airbags. This will allow the one-stage legs to dangle off the ground, which will release the internal locking system. Pneumatic actuators are then used to move the locking pins, which are operated by pneumatic push-button pilot valves mounted inside a control box on the side of the trailer.

In embodiments both landing Legs will move at the same time via a dual split junction box mounted between the leg sets. The trailer can then be lowered by the tractor so that it is fully supported by the locked leg. To raise the legs, the trailer is first lifted via the tractor-airbags and the locking actuators used to release the locking pins. The raise and lower actuators are then used to raise the lower leg portions. Once both legs are fully raised, the locking pin actuators are then used to engage the locking pins into second holes through the lower leg portions. BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic front view of a fully retracted landing leg.

Fig. 2 is a schematic front view of a fully extended landing leg.

Fig. 3 is a schematic front view of the landing leg system affixed to a trailer. Fig. 4 is a schematic front view of a second embodiment of the landing leg having a plurality of locking positions;

Fig. 5 is a schematic front view of a further embodiment of a landing leg in a partially extended state and with a locking peg or device in its release position.

Figs 6a and 6b are front and rear trimetric views of the landing leg of Fig. 5 in its extended state but with no foot attached;

Figs 7a and 7b are front and rear views as Figs 6a and 6b in the retracted state; Figs 8a and 8b are side and front views of a leg of Fig 5 in its extended state and part of a semi-trailer chassis to which the leg is attached; and

Figs 9a and 9b are views corresponding to Figs 8a and 8b but with the leg in a retracted state.

DESCRIPTION OF PREFERRED EMBODIMENT

The first member may comprise an upper leg portion the second member may comprise a lower leg portion telescopically mounted within the upper leg portion and adapted to be axially extensible between a raised or retracted position and a lowered extended position. The lower leg portion may be moveable downwardly from the retracted position to the extended position by means of gravity acting on its weight and alternatively, or in addition, the lower leg portion may be moved from the retracted position to the extended position by the actuator means which may be a pneumatic ram which is preferred as discussed below, an hydraulic ram or other mechanical means. The landing may have locking means operable to lock the lower leg portion relative to the upper leg portion and the locking means may comprise a locking peg and a corresponding latching means, disposable adjacent the bottom end of the upper leg portion.

The landing leg may be adapted to be used with trailers of different sizes and to be fitted at the back end of a tipper type trailer. Alternatively, or preferably in addition the locking peg and corresponding latching means are disposable adjacent the top end of the lower leg portion. The locking peg and the latching means may be disposable adjacent the upper leg portion. The locking means may be adapted to engage the locking peg using the actuator means. The locking means may engage the locking peg into a locked position or an unlocked position. In addition, the locking means may engage the locking peg into an unlocked position. The locking means may comprise a single acting actuator or a double acting actuator

The actuator may be provided with spring means to urge the peg to the locked position. The locking means may be used in one mode to prevent the extended lower leg portion from retracting into the upper leg portion, and in another mode to prevent the retracted lower leg portion from extending out of the upper leg portion, when the landing leg is in the retracted or raised position. The locking means may be operable to move the peg from the locked position, where the peg is positioned above the top edge of the lower leg portion, preventing the lower leg portion from retracting by using the pneumatic actuator means and to retract to an unlocked position, thereby enabling movement of the lower leg portion between the retracted position and the extended position.

The lower leg portion may be provided with slot means, which in use, is operable to fixedly locate the peg in a locked position, thereby preventing the lower leg portion from extending from a locked position within the upper leg portion.

In the event of loss of the air supply, the landing legs may be adapted to be extended or retracted by suitable manual means.

In a preferred embodiment the landing legs can be lowered into only a single in- use position. This means that trailers with the landing legs of the present invention will always be parked at a single chosen height and makes coupling tractor units to parked semi-trailers easier, and reduces the problems associated with known prior art devices which can support a trailer at any height Such embodiments are illustrated in Figs 1 , 2 and 5.

Referring to Fig. 1, a telescopic landing leg 1 has an upper leg portion 10, a lower leg portion 20, a pneumatically operable actuator 30 having a line of action generally parallel to the longitudinal direction of the leg and a foot 40. In a preferred embodiment, the landing leg has a square cross section with each side of the upper leg portion 10 being generally about 140mm wide;. It may be constructed from sheet steel which is about 5mm thick. The overall height of the landing leg can be varied to suit the trailer unit to which it is to be attached. Thus, the lower leg actuator could use different stroke sizes to accommodate for the different trailer chassis heights. The actuator 30 is fixed inside the upper leg portion 10 by a bracket 32 and suitable bolts to fix the bracket 32 to the upper leg portion 10 preferably at the top end of the upper leg portion. An actuator rod 31 is connected to the lower leg portion 20 at the top end of said lower leg portion preferably by using a threaded connection 21. It is retractable into the body of the actuator 30 to move the lower leg portion 20 to a raised storage position upon activation of the actuator 30 and is extensible to lower the lower leg portion 20 to the position shown in Fig. 2. Raising or lowering of the front of the trailer may be by the air bags of the tractor suspension and the duty of the actuator 20 is merely to move the lower part 20 between its upper and lower positions. For that purpose air at a relatively low working pressure, e.g. the working pressure of the tractor pneumatic system and e.g. about 2 bar suffices. The actuator could be hydraulic or other implementations providing the same function could be employed although there is no advantage in these alternative arrangements and it is less complicated to avoid the need for hydraulic or other auxiliary power. The present landing legs can also be used with a tractor which does not have adjustable air suspension and coupling height, for example it may be fitted with leaf springs. In such an instance, the tractor is adapted to use run up ramps to guide the fifth wheel under the trailer rubbing plate and once the kingpin has connected, the trailer height will move and allow the new legs to dangle off the ground, ready to be raised.

A bracket 52 welded to the upper leg portion 10 supports an upper end of a second pneumatic ram 50 having a line of action also generally along the longitudinal direction of the leg and having a rod 51 at its lower end. A bolt or pin secures the body of the actuator 50 to the upper leg portion bracket 52. A locking peg 60 is carried by a further bracket (not shown) connected to the upper part 10 below the bracket 52 and is pivoted to that bracket on pivot pin 53. The distal end of the rod 51 is connected to the locking peg 60 by a ball joint or the like and the arrangement of the ram 50 and the lever 60 is such that extension or retraction of rod 51 can bring about rotation in either direction of the peg 60. A lower finger portion of the peg 60 on rotation by ram 50 can be extended into and retracted from a slot 11 located towards the upper end of the leg upper portion 10 in a side thereof. In its extended rotational position the finger either engages socket 22 located towards the lower end of lower leg portion 20 to hold the lower leg portion in its retracted position (Fig. 1) or rests on a top plate 33 of the lower leg portion 20 to prevent the lower leg portion from retracting and to provide support for the vehicle body when the tractor is uncoupled, the load from the front end of the vehicle passing from upper leg portion 10 through the finger to lower leg portion 20 and the foot 40 and into the ground, the finger being load-bearing. For moving the lower leg portion between extended and retracted positions, air is supplied to the rod side of ram 50 to retract rod 51, rotating the peg 60 anti-clockwise as viewed in Figs 1 and 2, disengaging the finger from socket 22 or plate 33 and withdrawing it from slot 11 so that the lower part 20 is free to move.

When the landing leg lower portion 20 is fully extended by the actuator rod 31 to assume its extended position and when the locking peg 60 has been urged into the locked position by full extension of the second actuator rod 31, the locking peg 60 will prevent the lower leg portion 20 from retracting, and assumes its load bearing position once the tractor is uncoupled. When the lower leg portion 20 is moved up into the upper leg portion 10 by full retraction of the rod 31 into the body of the actuator 30, then the locking peg 60 is engaged into the aperture 11 at the bottom end of the upper leg portion 10 and through a crevice 22 or socket at the bottom end of the lower leg portion 20. This position is the storage position and the lower leg portion 20 is prevented from extending to the extended position by the locking peg 60 interlocking with the crevice 22 at the bottom end of the lower leg portion 20.

Referring now to Fig. 2, a fully extended landing leg comprises an upper leg portion 10, a lower leg portion 20 telescopically aperture 11 mounted therein, and an actuator 30. The landing leg is now ready to support the trailer once the tractor unit has been uncoupled.

In a preferred embodiment, as a security precaution, a key operated lock is mounted on the exterior of an upper leg portion 10 to prevent movement of the locking peg 60. This enables the landing leg to be locked in the fully extended position to prevent the landing leg from being raised by an operator, and also enables the landing leg to be locked in the fully retracted position to prevent the landing leg from being lowered whilst the tractor unit is connected, to prevent unauthorized uncoupling. In this embodiment, a key operated lock (not shown) engages with the locking peg 60 to prevent the locking peg 60 from being removed from the slots of the upper 10 and lower leg portions 20. This key operated lock can be regarded as a tertiary lock further safeguarding the leg against unintended movement from its extended or retracted states.

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 and the trailer chassis. The actuator is only sufficiently powerful to move the locking pin and lower leg portion rather than being sufficiently powerful to raise the trailer to which it is attached. The locking means described is of simple construction, yet is safe, reliable and can be incorporated into an automated system.

Generally, the landing legs are connected to the trailer by brackets. Each landing leg is connected to the other by a cross rail which is substantially perpendicular to the direction of motion of the lower leg portions 10. The landing leg can be fitted to the Off side' or the 'near side' of the trailer. Locking pegs 60 are mounted on the upper leg portions 10 by brackets 52, such that they are moveable by actuators 30 to lock or unlock the locking pegs 60. The actuators 30, 50 may be activated remotely. Activation of an actuator causes a locking peg 60 to move through a aperture 11 to enable the lower leg portion 20 to pass by and the locking peg 60 will return back to the locked position once the lower leg portion has been raised to the full retraction of the actuator rod 31 into the body of the actuator 30. The aperture 11 will enable the locking peg 60 to fit into the crevice 22, cut-out or socket at or towards the bottom end of the lower leg portion 20.

A control box with two pilot valves can be fitted on one side of the trailer, which can be connected to a junction box. The junction box can direct the air to both landing legs using suitable tee piece fittings, so that both landing legs will move at the same time using one control box. In a preferred embodiment, the actuator for the locking peg 50 is independently controlled from the actuator 30 for the lower leg portion 20. Fig. 3 is a diagrammatic view taken transversely of the vehicle chassis and shows in section two I-section chassis longitudinals 92 and portions of a cross-member attached to the longitudinals. A pair of legs is attached to the chassis in manner known per se and is mechanically interconnected by spacer bar 98 and bolts 91. A control unit 96 for the legs has two-position control buttons A and B for pilot valves or the like for respectively extending and retracting rams 30 and 50. The arrangement of rams 50 and locking pegs 60 for the two legs is generally indicated by the shaded regions 99. The control unit 96 is operably connected to a common junction box 97 for the two legs, lines diagrammatically indicated at 95 and 97 passing from the junction box 97 to piston and rod sides of the rams 30 of the two legs. Similar lines (not shown) pass from the junction box 97 to the piston and rod sides of the rams 50 that control locking pegs 60. With this arrangement a driver can engage and release the pegs by appropriate movement of two-position button B and can extend and retract the lower leg portions 20 by appropriate movement of two-position button A. Alternatively, a control box with two pilot valves can be fitted near to, or inside each landing leg so that each landing leg can move separately from the other.

The two landing legs can therefore be controlled by the driver or by another operator from the control box 96. Firstly, to lower the landing leg lower portion 20 to the fully extended in-use position from the fully retracted storage position the manually operable switch B is finger-operated to cause the locking peg 60 to assume an unlocked position by retracting the actuator rod 51 into the body of the actuator 50. The operator may then operate the switch A to enable the lower leg portion 20 to move downwardly by extension of the actuator rod 31. Once the lower leg portion 20 has passed the locking peg 60 then the first switch B is manually operated to reverse the initial action, moving the locking peg 60 back to the locked position by moving the actuator rod 51 out of the body of the actuator 50. The locking peg 60 will now prevent the lower leg portion 20 from retracting into the upper leg portion 10 and this is the in-use position when the landing leg is supporting the trailer, once the tractor is uncoupled. To raise the lower leg portion 20 from the extended position, switch B is manually operated in the reverse of the previous operation enabling the locking peg 60 to retract to an unlocked position by return of the actuator rod 51 into the body of the actuator 50. The operator must then operate switch A to move the lower portion 20 of the landing legs upwardly by retracting the rod 31 into the body of the actuator 30. Once the lower leg portion 20 bottom crevice or socket 22 has reached level with the locking peg 60 then the switch B is operated to move the locking peg 60 back to the locked position such that the locking peg 60 is then wedged through the aperture 11 at the bottom end of the upper leg portion 10 and the crevice or socket 22 at the bottom end of the lower leg portion 20, thereby preventing the lower leg portion 20 from extending. This is the assumed storage position when the tractor is coupled to the trailer with the landing legs fully raised, ready for a road journey.

In a further embodiment, (Fig. 4), the lower leg portion is provided with a number of crevices or sockets distributed along its length instead of a single crevice or socket (as is shown in Figs. 1 and 2).

The actuator can be fitted with magnetic positioning sensors on the body of the actuator, and by utilizing the rod movement, it is possible to stop the rod at any point on the body of the actuator by fixing the sensors in one or more positions on the actuator body. The steel rod can sense the switch on the body of the actuator, and can be adapted to move the lower leg portion to any chosen position within the lower leg portion, in one preferred embodiment.

This means that the locking peg can engage the lower leg portion at different points, allowing the landing leg to assume positions of varying heights, such that the locking peg would fit into any of the crevices or sockets in order to support the trailer, depending on the distance that the lower leg portion has dropped. For example, if the lower leg portion contacts the ground, then the locking peg will lock into the nearest crevice on the lower leg portion. This means that the landing leg could be used on trailers of different coupling heights and if necessary, could function on uneven ground.

Fig. 5 is a more detailed view of a second embodiment of the leg in which the same reference numerals as in Figs. 1 and 2 are used in relation to corresponding parts. Front and rear views in the extended and retracted state are also shown in Figs 6a, 6b, 7a, 7b. It will be seen that the peg or locking member 60 controlled by ram 50 is formed with a slot 70 in which a pin at the end of rod 51 runs, the pin moving along the slot as the rod 51 is extended or retracted, allowing the rod 51 to be coupled to the member 60 and to make simple translational movements as the member 60 is rotated between its locking and release states. Tongue 71 which is extendible through and retractable from slot 11 is also seen. The leg upper region 10 extends below slot 11 as at 77. Lower leg 20 incorporates a tube 74 into which fixing member forming part of a foot e.g. 40a as shown in Figs 8 and 9 can be received.

It will be noted that top plate 33 is formed with an upstanding ridge 79 which when the leg is fully extended and the locking member has been rotated into engagement with it engages into recess 75 on the underside of finger 71. When the leg has been lowered into ground contact and the tractor has been uncoupled, engaged recess 79 and latch 75 which are under load because finger 71 is weight-bearing form a secondary lock which holds the finger 71 in its engaged position and prevent it from being disengaged. In this embodiment, when the landing leg is extended and is in use, and it is desirable to move the locking peg 60 to the unlocked position, the landing leg upper portion 10 must firstly be raised slightly by a small height, for example 10mm relative to the lower leg portion 20 to create a small gap between the locking peg 60 contact surface and the top cap 33 section of the lower leg portion 20, freeing the ridge 79 from the recess 75 and therefore enabling the locking peg 60 to be disengaged from the top cap 33. Methods for raising the landing leg upper portion 10 include raising the whole trailer for example by inflating airbags connected to the tractor unit which tows the trailer, which will adjust the trailer front height and enable the tractor to support the trailer, thus alleviating the load from the locking peg 60 and the top cap 23 of the lower leg portion 20. The ridge 79 and recess 75 as explained above define a re leasable secondary lock that improves the security of the primary lock provided by lever or peg 60 and finger 71.

A similar secondary lock is provided by depending ridge 78 in socket 22 (which as best seen in Figs 6a and 8a has a slot-like opening) and recess 76 in the top face of the finger 71. When the lower portion is fully raised, the locking finger 71 is in place in recess or socket 22 and the lower portion is allowed to return slightly to lower the socket 22 into contact with the top face of the finger 71, ridge 78 engages recess 76 to form a further secondary lock preventing unintended release of the finger 71 from the socket 22 and hence unintended re-extension of the lower portion 20. When the landing leg is in the raised position, the locking peg cannot move to unlock until the lower leg portion 20 has slightly moved upwardly in order to create a small gap between the top face of the locking peg finger 71, and the top face of the hole 22 at the bottom end of the lower leg portion. This also ensures that the actuator 30 is always primed with compressed air, before the locking peg 60 is moved which will enable the lower leg portion 20 to lower in a controlled manner utilizing an air cushioning device on the actuator. For example, when the landing leg is in the raised position, to move the locking peg to the unlocked position, the lower leg portion must be raised by a small distance e.g. 10mm relative to the upper leg position. Methods for raising the lower leg portion include operating the connected actuator to move the actuator rod to full retraction. Alternatively, the lower leg portion can be moved manually by an operator before operating the locking peg.

In Figs 8 and 9 the legs are shown attached to chassis longitudinals 92 and attached to cross-member 92a by angled bracing struts 98a.

In another preferred embodiment (not shown) the locking peg has a raised projection on the top surface which interacts with the hole or socket 22 at the bottom end of the lower leg portion which may be formed with a corresponding internal recess.

In a different embodiment, the landing leg can be activated by use of remote control apparatus, or by an electronic signal unit controlling the control pilot valves. For example, upon coupling the tractor to the trailer, once the air lines have been connected, the landing legs could be adapted to retract automatically. In a similar manner, while uncoupling, the landing legs could lower automatically upon disconnection of the air lines. This would be possible by connecting the landing leg system air supply directly to the trailer air tanks. In addition, or alternatively, the landing leg can be operated manually by an operator. For example, a hoop-handle can be welded to the bottom end of the lower leg portion, which can be utilised to move the lower leg portion upwards or downwards.

The locking peg 60 can be moved to unlock by simply squeezing an extendible member of the swiveling bracket, to move the locking peg 60 to the unlocked position. The lower leg portion can be moved up or down with the hoop-handle and then the locking peg 60 can be manually pushed back into the locked position to hold the lower leg portion 20 up in a raised storage position, or down in the assumed in-use position, ready to support the trailer once the tractor is uncoupled.

In order to uncouple the tractor unit, the operator (who is usually the driver) must first lower both sets of legs. This is time consuming and hard work for the operator. The present invention makes raising or lowering the landing legs most user friendly such that at a push of a button, or by electromagnetic wireless control from the drivers cab area, the legs can be deployed. Some draw-bar combinations have automatic coupling systems that will secure the trailer coupling apparatus and connect the air and electric supply lines, without having to get out of the cab. The landing legs of the present invention can be adopted to be used with the automatic coupling device for draw-bar trailers, described above. The automatic coupling draw-bar trailers are especially convenient for operators who work in unsuitable temperatures, for example in subzero conditions, since the risk of frostbite is significantly reduced when an operator can control machinery from the safety (and warmth) of the cab area of the tractor. The landing legs of the present invention can be adapted to compliment the automatic procedure.

This embodiment has a number of advantages over the prior art; Firstly the landing leg can be deployed swiftly and easily in a quick manner, as there is no need to physically unwind the lower leg portion as is the case with prior art 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 types. The landing leg can be deployed by simply moving the locking peg. Known modern tractor units can carry the load of the trailer during this process, and can raise and lower the trailer to enable 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 the 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.

Having described and illustrated the principles of the invention with reference to preferred embodiments thereof, it will be apparent that the invention can be modified in arrangement and detail without departing from such principles. Accordingly, in view of the many possible embodiments to which the principles may be put, it should be noted that the detailed embodiments are illustrative only and should not be taken as limiting the scope of the invention.

For example, in another preferred embodiment a nut can be welded into the bottom end of the lower leg portion, and a screw can be rotated clockwise or anti clockwise from the nut, by means of a pneumatic or electric motor mounted inside the lower leg, and a foot plate welded to the bottom end of the screw can be utilized as a compensating foot. In the event that the lower leg fully extended does not meet the ground then the screw can be rotated out of the lower leg portion to compensate for the height difference. The footplate and screw could be moved manually by an operator, or the screw and footplate could be moved by a motor connected to the screw.

As another example, in an 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, whereby only a single landing leg (as opposed to two) is required to support the trailer. In any of the embodiments the upper leg portion may comprise an outer box section and a 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. The landing legs of the present invention can be utilised by a draw-bar trailer. This type of trailer needs support at the front end of the trailer and some cases, at the back of the trailer.

Claims

1. A vehicle landing leg comprising upper and lower portions telescopically fitting together for movement between an extended state in which when fitted to a vehicle the lower portion makes ground contact and a retracted state in which when fitted to a vehicle the lower portion is above ground, actuating means for effecting movement of the lower portion between extended and retracted states and latching means pivotally secured to the upper portion and engageable through an opening in the upper portion with the top of the lower portion to maintain the leg in its extended state and with a keep located towards the lower end of the lower portion to maintain the leg in its retracted state.

2. The leg of claim 1 wherein the upper and lower portions are of square cross- section.

3. The leg of claim 1 or 2, wherein the actuating means is a ram.

4. The leg of claim 3, wherein the actuating means is a pneumatic ram connected between the upper and lower portions.

5. The leg of any preceding claim, wherein the latching means is pivoted to the upper portion and a second ram is secured between the upper portion and the latching means for extension of the latching means into engagement with and for retraction of the latching means from engagement with the lower portion.

6. The leg of claim 5, wherein the second ram is a pneumatic ram.

7. The leg of claim 5 or 6 wherein the second ram has a line of action generally parallel to the longitudinal direction of the leg.

8. The leg of any preceding claim, wherein the keep is a slot through the lower portion.

9. The leg of any preceding claim, wherein the keep is a socket or recess formed in the lower portion.

10. The leg of any preceding claim wherein the lower portion of the leg and the latching means have formations that inter-engage in at least the extended state of the leg to provide a secondary lock against unintended movement of the lower portion from its extended state.

11. The leg of claim 10, wherein the lower portion of the leg and the latching means have first formations that inter-engage in the extended state of the leg to provide a secondary lock against unintended movement of the lower portion from its extended state and second formations that inter-engage in the retracted state of the leg to provide a secondary lock against unintended movement of the lower portion from the retracted state.

12. The leg of claim 10 or 11, wherein the secondary lock(s) is/are releaseable on slight lifting of the lower portion from the extended and/or retracted state.

13. The leg of any preceding claim, further comprising a key-operated lock for locking the lower portion against unintended movement from its extended and/or retracted state.

14. The leg of any preceding claim, further comprising a foot for ground engagement located at the lower end of the second portion.

15. The leg of claim 14, wherein the foot is a structure selected from a plate, a rocker and a wheel.

16. A trailer vehicle having a body fitted with at least one leg as defined in any preceding claim.

17. The vehicle of claim 16 fitted with at least one pair of legs.

18. The vehicle of claim 16 or 17, wherein the legs of the pair are connected at a single junction box to a common fluid supply and control system for simultaneous movement between extended and retracted positions and for simultaneous engagement and disengagement of the latching means.

19. The vehicle of claim 15, 16 or 17 which is a drawbar trailer.

20. The vehicle of claim 15, 16 or 17 which is a semi-trailer.

21. A demountable shipping container for carriage on a vehicle having legs on which the container can stand when the container is demounted, the legs being as defined in any of claims 1-15.

22. A rig comprising a tractor and a trailer vehicle coupled thereto the trailer vehicle having legs as defined in any of claims 1-15.

23. The rig of claim 22 having a pneumatic suspension.

24. The rig of claim 23, which is a semi-trailer, wherein the pneumatic suspension is adjustable to lift and lower the front of the trailer portion.

25. The rig of claim 3 or 24, wherein an air supply of the tractor is connected to a fluid supply and control system for the leg or legs.

26. A rig comprising a vehicle having a chassis on which a demountable shipping container as defined in claim 21 is carried.