GB2340796A

GB2340796A - Extendible flatbed trailer with movable crane

Info

Publication number: GB2340796A
Application number: GB9818266A
Authority: GB
Inventors: Kevin William Raven; Paul Anthony Raven
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-08-22
Filing date: 1998-08-22
Publication date: 2000-03-01
Anticipated expiration: 2018-08-22
Also published as: WO2000010834A1; GB9818266D0; GB2340796B; AU5633099A

Abstract

An extendible flatbed trailer (1), which may be connected to a tractor unit, comprises a chassis section (2) that has a first platform with a load bearing first floor surface (4), and a wheeled bogie section (3), the bogie section (3) having a second platform with a load bearing second floor surface (5). The bogie section (3) is slidably connected to the chassis section (2) and relatively movable between extended and retracted positions, the second floor surface (5) relatively extending from underneath the first floor surface (4) as the sections (2, 3) are moved from a retracted to an extended position. One section (2) has a track (17) and a crane (40) with running gear (41) that engages with the track (17) so that the crane (40) may travel over a floor surface (4) between a forward and a rearward position, the reach and travel of the crane being sufficient to load or unload the other floor surface (5) when the trailer (1) is extended.

Description

2340796 Extendible Flatbed Trailers The present invention relates to

extendible flatbed trailers which may be connected to and towed by a tractor unit, and in particular to extendible flatbed trailers having sections that may be retracted or extended with respect to each other, and a wheeled crane movable along a load carrying floor of one of the sections.

There are many varieties of flatbed trailers which may be connected to and towed by a tractor unit. Some consist mainly of a floored surface above the trailer frame; others have additional structural elements, for example, fold-down sides, curtain sides or top, rigid sides or top, and is vertical side pillars. Such trailers are often used to transport a wide variety of items such as palletised goods, concrete or steel beams and logs.

Because a f latbed trailer may at times need to be only partially loaded, it may be desirable for the flatbed trailer to be extendible. One example of an extendible flatbed trailer is described in EP 0 551 159 A1 which discloses a trailer with curtain sides and top with a flatbed floor in two sections. The floor sections are centrally supported on an extendible box-within-abox chassis, with the forwards floor section sliding over the rearwards floor section as the trailer is retracted. Such a trailer may be loaded by a separate crane or by a forklift truck.

Another type of extendible flatbed trailer is disclosed in WO 96/25302. This discloses a flatbed trailer having a forwards chassis section and a rearwards bogie section and with a crane mounted either on one end of the trailer or on the tractor unit close to the trailer, so that the crane may load and unload the trailer. In order to keep the size and hence the cost and weight of the crane to a minimum, the crane has a reach which is sufficient to load or unload the section that would be farthest from the crane when the 5 sections are extended, only when the sections are retracted. As a result, the crane is mounted on or nearest the section that has a floor that retracts underneath the other floor. Whilst this approach is effective, the cost of such a crane is still a significant part of the cost of such a trailer.

It manufacturing such a trailer, is also necessary to decide in advance where the crane is to be mounted, but different users of such an extendible flatbed trailer may prefer different locations for the crane.

It is an object of the present invention to provide an extendible flatbed trailer with a more convenient crane.

Accordingly, the invention provides an extendible flatbed trailer comprising a chassis section, the chassis section having a first platform with a load bearing first floor surface, and a wheeled bogie section, the bogie section having a second platform with a load bearing second floor surface, wherein:

a) the bogie section is slidably connected to the chassis section and relatively movable between extended and retracted positions, the second floor surface relatively extending from underneath the first floor surface as the sections are moved from a retracted to an extended position; b) each floor surface is supported by its respective section as the sections are moved between extended and retracted positions; and c) one section has a track and a crane with running gear that engages with the track so that the crane may travel over the a floor surface between a forward and a rearward position, the reach and travel of the cane being sufficient to load or unload the other floor surface when the trailer 5 is extended.

The width of a typical flatbed trailer may be up to 2.55 m, and the length may be between typically 6.09 m and 13.7 m (20 feet and 45 feet), so the platforms will generally be elongate. Such a platform will present a load bearing surface which may be walked over and which may readily be used to support goods such as pallets, or the weight of a forklift truck.

The crane may be mounted on the second section, in which case at least part of the second section will not be retractable under the first section as the sections are moved to the retracted position. However, so that the sections may be fully retracted, or nearly fully retracted, it is advantageous if the crane is mounted on the first section. Then, because the crane may travel towards the second section when this is extended, the crane may be used to load the second section, either before or after loading the first section.

At least one section, and preferably each section, may have a pair of longitudinal frame members to support a loadbearing platform. A pair of parallel longitudinal frame members may be spaced equidistantly from a longitudinal centre line of the trailer, with a first frame member from one section slidably retained within a second frame member from another section.

In a preferred embodiment of the invention, one pair of 35 frame members is nested inside the other pair, the second floor surface having a pair of longitudinal slots therethrough to accommodate the movement of the chassis frame members as the trailer is retracted or extended.

In general, at least one section may have transverse frame members in order to support the platform. The transverse members may be fixed to a longitudinal frame member, and may optionally extend across the width of a load-bearing platform, in order to support better the platform.

A section may have a transverse frame member supporting a platform, the transverse frame member extending across the width, and preferably the full width, of a platform through apertures cut in each of a pair of the longitudinal frame members.

The second floor surface may comprise adjacent the slots a pair of opposite longitudinal side surfaces each of which is laterally cantilevered by supporting members extending beneath the slots. A supporting member may extend transversely from a longitudinal frame member, for example, being welded to a longitudinal member. Alternatively, the supporting members may be continuous and extend across the width of a load-bearing platform.

If the bogie section has on a side of the trailer at least two road-going wheels, the wheels being spaced longitudinally from each other, a supporting member may advantageously extend through the space between two of the wheels. This permits the supporting member to be more substantial, and hence stronger, than if the supporting member were shaped to bend or arch around the top of a wheel. Furthermore, the supporting member may be used to support a mud flap between wheels.

The longitudinal frame member may be an I-beam, and if the other section has a pair of longitudinal frame members in the form of inwardly opposed C-beams, the I-beams may be slidably movable within the C-beams. For reasons of economy however, in a preferred embodiment, however, each longitudinal frame member is an I-beam. The frame members may be of steel or, if maximising the weight of loads to be carried is important, extruded aluminium.

The means are preferably operable independently of the crane, in which case an interlock device may be provided such that the crane may not be activated until the trailer has been secured in the extended or retracted position.

The trailer will generally have means by which the sections may be secured in extended and retracted positions. For example, the sections may be securable in an extended or a retracted position by a locking mechanism comprising a pin on one section relatively movable between a pair of inwardly 20 facing fifth-wheel type clasps on the other section. Alternatively, the sections may be securable by transversely movable pins, which seat through matching aligned apertures in the nested frame members.

The extendible flatbed trailer may also have additional structural elements above the floor of a platform for containing a load. For example, the trailer may have any of fold-down sides, curtain sides or top, rigid sides or top and vertical side pillars.

Also according to the invention, there is provided a method of loading an extendible flatbed trailer, the trailer being as claimed in any preceding claim, wherein the method comprises the steps of:

a) extending the sections to pull the second platform out from underneath the first platform; b) positioning the crane along the track of one platform 5 so that the crane is proximate the other platform; and c) using the crane to load said other platform.

The method may also comprise the step of securing the sections in an extended or retracted position after extending or retracting the platform but before loading the platform with the crane.

If the crane is on the first platform, then it may be preferable if, prior to step a) the first platform is loaded first. This permits the movable crane to load the first platform by collecting loads from the rear of the trailer, whilst the second floor is retracted underneath the first floor. This may be needed, for example, if the trailer is being used to load from a loading dock or other location into which the trailer has been backed.

The trailer may then be unloaded by using the crane to unload the second section, then retracting the sections to retract the second platform underneath the first platform, and finally using the crane to unload the first platform.

Optionally, the crane may be positioned along the track so that the crane may unload the first platform to the rear of the trailer.

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

Figure 1 is a top view of the extendible flatbed trailer according to the invention, showing a bogie section and a chassis section in between extended and retracted positions and with a crane on a forward platform; Figure 2 is a cross-section view of the extendible flatbed trailer taken through line II-II of Figure 1; and Figure 3 is a side view of the extendible flatbed trailer of Figures 1 and 2; Referring to al three Figures, an extendible flatbed trailer 1 has a forwards chassis section 2, and a rearwards bogie section 3, each of which has a platform 104,105 with a load bearing floor surface 4,5. The chassis section 2 has a standard mounting king pin 6 for a fifth-wheel connection to a tractor unit (not shown), and drop-down front support legs 7 shown in the dropped position in Figure 3. 20 The rear bogie section 3 has three axles 7 with six wheels 8. The trailer 1 could have fewer sets of wheels, but for larger types of trailers it is preferable to have three axles in order to provide a greater potential load bearing capacity. For the sake of clarity in the drawings, the details of the axle suspension and connection to the rear bogie section 3 are not shown.

The front chassis section 3 of the extendible trailer 1 has two fifth-wheel type automatic locking mechanisms 10,11 mounted beneath the level of the forward floor 5 on the longitudinal centre line of the trailer 1. The rear bogie section 2 of the trailer 1 has a f ixed pin 9 which is vertically aligned and which engages with and automatically latches within either of the locking mechanisms 10,11 when the trailer 1 has been extended or retracted into position. Since the trailer 1 is shown between fully extended and retracted positions, the pin 9 is shown between the locking mechanisms 10,11.

The trailer 1 is suitable for carrying palletised loads 50 and other solid or packaged goods which may be strapped down to the floor of the flatbed sections.

Both the front and rear sections 2,3 have a pair of parallel longitudinal frame members 17,18 made from steel I-beams, spaced equidistantly from a longitudinal centre line of the trailer 1. The chassis section I-beams 17 taper down towards the front of the trailer in the region of the supporting king pin 6, where the required strength of the frame members 17 is least, in order to save weight and to reduce the height of the floor 4.

As can be seen f rom Figure 1, the top of both pairs of I-beams 17,18 forms part of both floor surfaces 4,5 of the floor platforms 104,105. Since the floor surfaces 4,5 may be formed from light-weight materials such as wood or aluminium alloy sheets, the top surfaces of the I-beam provides reinforcement to help protect the floor surfaces 4, 5 from damage during loading and loading of the trailer 1.

The pairs of frame members are nested; that is, the bogie section pair 18 is transversely spaced inside the chassis section pair 17, as can be seen in Figure 2. The chassis section frame members 17 are held together at their ends by steel transverse end frame members 20,21 at the front and rear of the chassis section 2, and by steel extending between the frame members around the forward locking mechanism 10. Similarly, the bogie section frame members 18 are held together at their ends by steel transverse end - 9 frame members 22,23 at the front and rear of the bogie section 3, and by structural steel extending between the frame members around the rearward locking mechanism 11.

The chassis section platform 104 is supported at forward and rearward ends by the transverse end frame members 20,21 and also by a number of lightweight aluminium transverse intermediate frame members 27 spaced at longitudinal intervals between the end frame members 20,21. The intermediate frame members are aluminium I-beams that extend continuously across the width of the platform 104, through I-shaped apertures cut through both chassis longitudinal frame members 17.

Five of the intermediate frame members 27 between the locking mechanisms 10,11 are partially cut through by a channel 30 along the central longitudinal axis of the trailer 1 to allow passage of the vertical pin 9 between the forward and rearward locking mechanisms 10,11.

As can be seen in Figure 2, atop each of the intermediate frame members are bolted three aluminium C-beams 32,33,34. Each C-beam 32-34 is aligned parallel with the underlying Ibeam 27. This arrangement has two benefits. First, the I-shaped apertures through the chassis section longitudinal frame members is closer to the middle of the I-shaped crosssection, as so has less adverse effect on the strength of the I-beam than if the aperture were nearer the top or bottom of the I-shaped profile. Second, the arrangement permits a narrow channel 35, about 25 mm wide, to be provided in the chassis section floor 4 immediately adjacent to each of the chassis section longitudinal frame members 17.

The narrow channel 35 serves to secure a crane 40 on the chassis section platform 104. The crane 40 has four steel wheels 41, aligned longitudinally in two pairs to run along the top surfaces of the chassis section longitudinal frame members 17. Each wheel runs on a fixed axle 42, the ends of which terminate in a bracket 43 angled down into the narrow channel 35. Each bracket 43 ends in a projection 44 than hooks laterally inwards underneath the top of the chassis section I-beam 17. The top of the I- beams 17 act as a track and the crane wheels 41, and brackets 43 with hooks 44 together form running gear which keep the crane 40 engaged with the track. The crane 40 is thereby retained to the chassis section 2 by the bracket 43 and narrow floor channels 35.

The narrow floor channels 35 run from the chassis section rear transverse member 21 to a point roughly midway along the length of the chassis section floor 4, thereby limiting the movement of the crane 40. The crane 40 has an articulated arm 45, and although not illustrated, is driven by a hydraulic supply from a small internal combustion motor in a known manner. At least one of the wheels 41 will be driven by the same motor that powers operation of the crane 40, so that the crane can be moved along the chassis section 2.

The reach and travel of the crane 40 is such that the crane may load and unload the bogie section platform 105, for example with a pallet of bricks 50 as shown in Figure 3. The reach and travel of the crane is also such that it may load and unload the front portion of the chassis section platform 104. If the bogie section 3 is unloaded, then the crane may rear to the rear of the trailer to load or unload goods.

The bogie section platform is also supported by members 35 beneath the floor 5. However, because the chassis section I-beam 17 is nested partly above the level of the bogie section I-beam 18, and because the weight of the chassis platform 104 is taken fully by chassis longitudinal frame members 17, it is necessary for the bogie section floor 5 to have a pair of longitudinal channels 31 into which the chassis section frame members 17 extend. The channels 31 run laterally outside and adjacent the bogie section longitudinal frame member 18 from the bogie section rear transverse frame member 23 to the front of the bogie section 3. The width of each of the channels 31 in the bogie section floor 5 is 100 mm, which is narrow enough for the channel not to interfere with many types of load, in particular palletised loads.

The channels 31 therefore divide the bogie section floor 4 into three separate surfaces, a central surface 46 between the longitudinal frame members 18 and two longitudinal side surfaces 47.

Because of the channels 31, it is necessary, with the exception of the rear transverse frame member 23, for the bogie section platform 105 supporting members to be provided separately in three areas: between the longitudinal frame members 18, and laterally outside of each of the channels 31. Between the longitudinal frame members 18, are a number of aluminium I-beams 29, similar to the chassis section transverse I-beams 27. Laterally outside of the bogie section longitudinal frame members 18 are four steel box section struts 28 that act as supporting members to support the longitudinal side surfaces 47. The struts 28 therefore support in cantilever fashion the longitudinal side surfaces 47.

Because the vertical clearance between the wheels 8 and bogie section platform 105 is limited, some of the struts 28 are provided in the space between the wheels and wheel mud guards 48. Mud flaps 49, _ and optionally the mud guards, 48 may be affixed to some of the struts 28.

The trailer 1 may be extended or retracting in the following manner. The chassis section members 17 each have three steel rollers 24, which run along the flat tops of the bogie section I-beams 18. As the sections 2,3 are moved between extended and retracted positions, the rollers 24 will roll along the lengths of the I-beams 24. Figure 1 shows a central portion of the chassis section floor 4 cut away to illustrate better the operation of the locking mechanism. The fifth-wheel type automatic locking mechanisms 10,11 stop the sections from moving beyond the extended and retracted is positions, when the pin 9 enters the latch and is captured and secured in place by a bolt 25 which is thrust across the pin 9. Each automatic locking mechanism 10,11 may be unlocked by means of an air driven line (not shown) which activates a pneumatic piston 26 to pull back the bolt 43 to release the pin 12.

The f latbed trailer 1 may be moved f rom an extended to a retracted position by locking the wheels 8, activating the air line to the rear latch 11 in order to release the vertical pin 9 whereupon the tractor unit may back down on the trailer until the front latch 10 becomes engaged at the retracted position.

For convenience and safety, the trailer is fitted with sensors and interlocks (not shown) so that each stage of the above process (e.g. retraction of pins, elevation of platform, etc) is sensed before the next stage may be activated by the air lines.

The extendible flatbed trailer 1 described above is 11.8 m - 13 long when in the extended position, and 8.7 m long when retracted. The crane movement along the chassis section floor 4 is limited by the narrow groove 35, which is 5.2 m long and the width of the trailer may be up to 2.55 m. The unloaded weight of the trailer is 6 tonnes, and when loaded may weight up to 44 tonnes, or higher according to limits set by national laws.

The extendible flatbed trailer may also be provided with additional structural elements above the floor of the sections. For example, the chassis section 2 may have dropdown sides, which would allow the trailer to haul a load which could not be fully secured by means of straps alone. The bogie section 3 could then be used for more securely packaged goods, for example pallets.

The extendible flatbed trailer could be fitted with curtain sides or top, or even with solid sides with a foldable top. In the latter example, the rear half of the sides could slot into a cavity in hollow-walled front sides when the trailer was retracted.

A particular advantage of the present invention is that it allows a trailer to be fully loaded for journey to locations for which there is good accessibility for a full sized trailer. Then after offloading at such a location, the trailer may be retracted and driven to another location, for example a city centre of a small yard or building site, where it might be difficult or impossible for a full length trailer to manoeuvre. Furthermore, the location of the crane at the rear of the chassis section allows the trailer then to unloaded, if need be, to the rear of the trailer. This may be most advantageous if the trailer has had to back into location.

The present invention also permits the trailer be loaded in like manner, that is with the chassis section f irst being loaded, optionally in a location with tight access, followed by loading of the bogie section, perhaps at another location 5 with easy access.

The ability to alter the length of the trailer could also provide other economies. For example, when travelling by ferry, the trailer could be retracted when not fully loaded and so reduce the length-related charges for the ferry crossing.

i

Claims

1. An extendible flatbed trailer comprising a chassis section, the chassis section having a first platform with a load bearing first floor surface, and a wheeled bogie section, the bogie section having a second platform with a load bearing second floor surface, wherein:

a) the bogie section is slidably connected to the chassis section and relatively movable between extended and retracted positions, the second floor surface relatively extending from underneath the first floor surface as the sections are moved from a retracted to an extended position; b) each floor surface is supported by its respective section as the sections are moved between extended and retracted positions; and c) one section has a track and a crane with running gear that engages with the track so that the crane may travel over a floor surface between a forward and a rearward position, the reach and travel of the cane being sufficient to load or unload the other floor surface when the trailer is extended.

2. An extendible flatbed trailer as claimed in Claim 1, in which the crane is on the first section.

3. An extendible flatbed trailer as claimed in Claim 1 or Claim 2, in which each section comprises a pair of longitudinal frame members, with one pair nested inside the other pair, the second floor surface having a pair of longitudinal slots therethrough to accommodate the movement of the chassis frame members as the trailer is retracted or - 16 extended.

4. An extendible flatbed trailer as claimed in Claim 3, in which the second floor surface comprises adjacent the slots a pair of opposite longitudinal side surfaces each of which is laterally cantilevered by supporting members extending beneath the slots.

5. An extendible flatbed trailer as claimed in Claim 4, in which the bogie section has on a side of the trailer at least two road- going wheels, the wheels being spaced longitudinally from each other, wherein a supporting member extends through the space between two of the wheels.

is

6. An extendible flatbed trailer as claimed in any one of Claims 3 to 5, in which each longitudinal frame member is an I-beam.

7. An extendible flatbed trailer as claimed in any preceding claim, in which a section has transverse f rame members supporting a platform.

8. An extendible f latbed trailer as claimed in one of Claims 3 to 6, in which a section has a transverse frame member supporting a platform, the transverse frame member extending across the width of a platform through apertures cut in each of a pair of the longitudinal frame members.

9. An extendible flatbed trailer as claimed in any preceding claim, in which the sections may be secured in an extended or a retracted position by a locking mechanism comprising a pin on one section relatively movable between a pair of inwardly facing fifth-wheel type clasps on the other section.

10. An extendible flatbed trailer as claimed in any preceding claim, in which the trailer has additional structural elements above a floor surface for containing a load.

11. A method of loading an extendible flatbed trailer, the trailer being as claimed in any preceding claim, wherein the method comprises the steps of:

a) extending the sections to pull the second platform out from underneath the first platform; b) positioning the crane along the track of one platform so that the crane is proximate the other platform; and is c) using the crane to load said other platform.

12. A method of loading an extendible flatbed trailer as claimed in Claim 11, in which the crane is on the f irst 20 platform.

13. A method of loading an extendible flatbed trailer as claimed in Claim 12, wherein prior to step a) the method comprises the step of:

d) using the crane to load the first platform.

14. A method of unloading an extendible flatbed trailer loaded according to Claims 12 or 13, wherein the method 30 comprises the steps of:

e) using the crane to unload the second section; f) retracting the sections to retract the second platform 35 underneath the first platform; and g) using the crane to unload the first platform.

15. A method of unloading an extendible flatbed trailer as claimed in Claim 14, in which step g) involves:

h) positioning the crane along the track so that the crane may unload the first platform to the rear of the trailer.

16. An extendible flatbed trailer substantially as herein described, with reference to or as shown in the accompanying drawings.

17. A method of loading or unloading an extendible flatbed trailer substantially as herein described, with reference to or as shown in the accompanying drawings.