Trailer with adjustable ground clearance

A simple mechanical height adjustment device adjusts the ground clearance of a trailer. The trailer, having the height adjustment device can selectably and reversibly increase its ground clearance. The trailer, having an adjustable ground clearance, can minimize its load height when operating on improved roads in order to meet local and state height regulation, but can increase its ground clearance on uneven roads.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for selectably adjusting the ground clearance of a towed trailer vehicle.

2. Description of the Related Art

Whenever, a trailer transports a high load it must minimize its load height to avoid the need for special routing or for hiring an escort as may be necessitated by local or state regulations. This problem is especially acute for the long trailers used for hauling oilfield equipment such as coiled tubing rigs used for well drilling and servicing. Coiled tubing rigs normally are rather tall, and the desirability of mounting an entire rig on a single trailer leads to the use of long trailers.

Further complicating this problem is the fact that many well locations are only accessible over very rough, uneven roads. Pulling long, low trailers loaded with heavy equipment over rough, uneven roads often leads to problems in expeditiously getting the oilfield equipment to a well site. This is particularly true, if it is desired to deliver the coiled tubing rigs to the well site on a single trailer.

A need exists for a simple, inexpensive means of adjusting trailer ground clearance which is easy to use.

SUMMARY OF THE INVENTION

This invention pertains to a device for adjusting the ground clearance of a trailer. One embodiment of the present invention includes a simple mechanical means for selectably and reversibly increasing the ground clearance of a trailer so that it can operate within a safe overall height limit when operating on improved roads, but can also operate with increased ground clearance on uneven roads.

One embodiment of the present invention includes a vehicle trailer comprising: (a) a rear deck; (b) a forward deck having a second end; (c) a central deck having a front end and a rear end, wherein the rear end is attached to the rear deck; and d) a pivotable altitude adjustment mechanism connecting the front end of the central deck to the second end of the forward deck, wherein the altitude adjustment mechanism includes a plurality of selectably engageable pin connections; whereby the forward deck and the central deck have a unique angular alignment with each other for each pin connection.

A second embodiment of the present invention includes a vehicle trailer comprising: (a) a rear deck; (b) a forward deck having a first end and a second end; (c) a central deck having a front end and a rear end, wherein the rear end is attached to the rear deck; and (d) a pair of pivotable altitude adjustment mechanisms connecting the front end of the central deck to the second end of the forward deck, wherein each altitude adjustment mechanism includes (i) a pair of rear pivot plates mounted on the front end of the central deck parallel to and offset from a longitudinal midplane of the trailer, wherein each rear pivot plate has a pivot hole and a plurality of position locking pin holes, (ii) a forward pivot plate mounted on the second end of the forward deck parallel to and offset from the longitudinal midplane of the trailer, wherein the forward pivot plate has a pivot hole and a plurality of position locking pin holes, and (iii) a pivot pin connecting the pivot hole of the forward pivot plate to the pivot holes of the pair of rear pivot plates when the pivot holes of the forward pivot plate and the rear pivot plates are coaxially aligned, and (iv) a selectably engageable position locking pin connecting one of a plurality of coaxially aligned position locking pin hole sets, wherein each set of position locking pin holes includes one position locking pin hole of the forward pivot plate and one position locking pin hole in each rear pivot plate, and whereby each set of position locking pin holes is associated with a particular height of ground clearance for the front end of the central deck.

Another embodiment of the present invention includes a vehicle trailer comprising: (a) a rear deck; (b) a forward deck having a first end and a second end; (c) a central deck having a front end and a rear end, wherein the rear end is attached to the rear deck; and (d) a pair of pivotable altitude adjustment mechanisms connecting the front end of the central deck to the second end of the forward deck, wherein each altitude adjustment mechanism includes (i) a first rear pivot plate having a first pivot hole and a plurality of position locking pin holes, wherein the first rear pivot plate is mounted on the front end of the central deck parallel to and offset from the longitudinal midplane of the trailer, (ii) a second rear pivot plate having a second pivot hole and a plurality of position locking pin holes, wherein the second rear pivot plate is mounted on the front end of the central deck parallel to the first rear pivot plate and offset from the first rear pivot plate towards the longitudinal midplane of the trailer, (iii) a forward pivot plate mounted on the second end of the forward deck parallel to and offset from the longitudinal midplane of the trailer, wherein the forward pivot plate has a pivot hole and a plurality of position locking pin holes, and (iv) a pivot pin connecting the pivot hole of the forward pivot plate to the pivot holes of the pair of rear pivot plates when the forward pivot plate is positioned between the first and second rear pivot plates and the pivot holes of the rear pivot plates are coaxially aligned with the pivot hole of the forward pivot plate, and (v) a selectably engageable position locking pin connecting one of a plurality of coaxially aligned position locking pin hole sets, wherein each set of position locking pin holes includes one position locking pin hole of the forward pivot plate and one position locking pin hole in each rear pivot plate, and whereby each set of position locking pin holes is associated with a particular ground clearance for the front end of the central deck.

The foregoing has outlined rather broadly several aspects of the present invention in order that the detailed description of the invention that follows may be better understood and thus is not intended to narrow or limit in any manner the appended claims which define the invention. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing of the structures for carrying out the same purposes as the invention. It should be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As a note, the use of the terms “invention”, “present invention” and variations thereof throughout the subject patent application (and headings therein) are intended to refer or relate to one or more embodiments of the present application, not necessarily every embodiment or claim of the application.

Referring now to the drawings, it is noted that like reference characters designate like or similar parts throughout the drawings. The figures, or drawings, are not intended to be to scale. For example, purely for the sake of greater clarity in the drawings, wall thicknesses and spacings are not dimensioned as they actually exist in the assembled embodiments.

The present invention pertains to a device for adjusting the ground clearance of a trailer. One embodiment of the present invention includes a simple mechanical means for selectably and reversibly increasing the ground clearance of a trailer so that it can operate within a safe overall height limit when operating on improved roads, but can also operate with increased ground clearance on uneven roads.

The materials of construction of the structural components of the height adjustment mechanism are typically those employed by other commercial highway vehicles. The tractor is generally a heavy duty commercially available vehicle which has a fifth wheel for towing a trailer and multiple rear axles. The tractor normally will have a steel frame and either a steel or fiberglass cab.

For hauling high loads, the trailer will preferably be a “low-boy” trailer with a depressed center section for carrying cargo at a lower height than would a standard trailer with a flat deck. The trailer normally is fabricated from steel because of the high weight and long span between its pivot pin and its multiple rear axles, although aluminum can be used for many parts in order to minimize vehicle weight. The trailer is provided with a pair of either hydraulic or mechanical jacks having foot plates for contacting the ground. The jacks are mounted at or near the forward and back ends of the depressed center section of the trailer.

Referring toFIG. 1, a tractor/trailer rig10utilizing the low-boy trailer20is shown in an oblique view hauling a tall rectangular load70. The tractor11is a heavy duty commercially available vehicle having a fifth wheel12for towing the trailer20and multiple driven rear axles. The load70is shown as a rectangular prism for simplicity, but can have a wide variety of configurations, depending upon the make-up and desired use of the load.

For example, when designing a trailer for mounting a coiled tubing rig for use in well drilling or servicing, the rig designer will normally make the reel for the tubing and the other rig components as large as possible to still be compatible with standard unpermitted vehicle height limits. This is done in order to permit using larger diameter tubing or more tubing on the reel or both.

FIG. 2shows a side profile view of the tractor11and trailer20of the present invention, wherein the trailer is in its lower first transit position, or highway towing position, suitable for unpermitted highway use. The highway ground clearance for the trailer ofFIG. 2is preselected by the trailer designer to be the minimum compatible with most paved roads, so that the practical load height can be maximized. However, the ground clearance of the trailer20as shown inFIG. 2is insufficient for rough roads.

Referring to bothFIGS. 1 and 2, the trailer20is seen to have a rear deck51which is necessarily elevated in order to provide clearance for the rear axle assemblies52. The rear deck51is flat and typically has a width of approximately 8 feet, while its length is generally somewhat longer in order to accommodate multiple rear axle assemblies. The rear axle assemblies include the axles, brakes, conventional spring supported suspensions, shock absorbers, wheels, and tires common to most conventional heavy duty trailers suitable for both highway and unimproved road use. The flat upper surface of the rear deck51is underlain and supported by longitudinal beams with smaller transverse cross beams (not shown). When in the highway towing configuration shown inFIG. 2, the rear deck51is substantially parallel to the approximately planar roadway80supporting the tractor-trailer rig10.

The rectangular main or central deck21of the low-boy trailer20has the same width as that of the rear deck51and is structurally connected to the rear deck by a short inclined deck segment which slopes downwardly in the forward direction. The central deck21is elongated and serves as the main load supporting area for the trailer20. When unloaded, the central deck21is generally cambered upwardly in its center. However, when the central deck21is statically loaded with its design load cargo70, the upper surface of the central deck is substantially planar.

Both the central deck21and the short inclined deck segment are connected to the rear deck51by continuous longitudinal beams to support the large bending loads associated with supporting the cargo on the central deck. Transverse cross beams are used to further stiffen and strengthen the deck surface of the central deck21, similar to the rear deck51. When in the highway towing configuration shown inFIG. 2, the main bed21of the trailer20is substantially parallel to the rear deck51.

An altitude adjustment mechanism24is used to join the central deck21to the forward deck54of the trailer20.FIGS. 4 and 5show exploded views of the altitude adjustment mechanism24. A pair of altitude adjustment mechanisms24are utilized to selectably adjust the ground clearance of the front end of the central deck21of the trailer, with one altitude adjustment mechanism24mounted on each side of the trailer20. The two altitude adjustment mechanisms24are symmetrical mounted about the longitudinal midplane of the trailer20.

Each altitude adjustment mechanism24includes three principle components. One pair of elements (the rear pivot plates25and30) of the altitude adjustment mechanism24is attached to the forward end of the central deck21, while the other element (the forward pivot plate) of the mechanism24is attached to the rear side of the forward deck54of the trailer20.

The two elements of each altitude adjustment mechanism24mounted on the forward end of the central deck21of the trailer20are a pair of substantially similar rear pivot plates25and30. The outboard or outer pivot plate25is mounted vertically with its outer side flush with the side of the main bed of the central deck21. The inboard or inner pivot plate30of each rear pivot plate pair is mounted vertically and aligned parallel to the outboard pivot plate25. Each inboard pivot plate30is spaced apart from its adjacent outboard pivot plate25in the direction towards the trailer longitudinal midplane.

Referring toFIG. 8, it can be seen that each rear outboard pivot plate25, and similarly each rear inboard pivot plate30, consists of an approximately 90° arcuate sector of a circle with a projecting tab on its lower horizontal straight side. Going counterclockwise from its righthand lower side as seen inFIGS. 5 and 8, the perimeter of each pivot plate25and30has a short first vertical edge61, a 90° arcuate edge62curving upwardly and to the left, a short first horizontal edge63, and a long vertical edge64. The short first horizontal edge63and the long vertical edge64are joined by a small radius arc.

Adjoining the long vertical edge64on its lower end is a short edge65inclined at approximately 45° from the vertical to slope downwardly toward the front portion of the central deck21to which the outboard pivot plate25is attached. Adjoining the inclined edge65is a second vertical edge66having a length equal to the vertical thickness of the central deck21. A long horizontal edge67extends from the second vertical edge66to the lower end of the first vertical edge61.

The center of the 90° arc edge62lies in the plane of the second vertical edge66. Each of the rear outboard25and inner30pivot plates is attached by welding to both the forward deck and the upper surface of the central deck21of the trailer20. The rear pivot plates25and30are strongly and rigidly connected to the structure underneath the upper load bearing surface of the central deck21of the trailer20. In particular, loadings are efficiently transferred between the rear pivot plates25and30and the longitudinal beams supporting the main bed of the central deck21of the trailer.

A large diameter pivot pin through hole26is aligned with the axis of the arcuate edge62of the outer pivot plates25. A corresponding large diameter pivot pin through hole31is aligned with the axis of the arcuate edge62of the inner pivot plates30and is coaxial with the through hole26of the outer pivot plate25.

For the rear outer pivot plates25, a first position locking pin hole27is located vertically at radius R above the pivot pin hole26. A second position locking pin hole28is located, clockwise from hole27by angle ΦA, at radius R from the pivot pin hole26. The first position locking pin hole27and second position locking pin hole28have substantially the same diameter, which is smaller than that of the pivot pin hole26. The pivot pin hole26and the position locking pin holes27and28are mutually parallel and normal to the longitudinal midplane of the trailer20.

For the rear inner pivot plates30, a first position locking pin hole32is located vertically at radius R above the pivot pin hole31, and a second position locking pin hole33is located at radius R from the pivot pin hole31clockwise from hole32by angle ΦA. The first32and second33position locking pin holes have the same diameter which is smaller than that of the pivot pin holes31. The pivot pin hole31and the position locking pin holes32and33are mutually parallel and normal to the longitudinal midplane of the trailer20. In addition, the first position locking pin hole27and the second position locking pin hole28of the outboard pivot plate25are coaxial with the corresponding first position locking pin hole32and the second position locking pin hole33of the inner pivot plates30.

A pair of hydraulic jacks44is located at the forward end of the central deck21of the trailer20. The jacks44typically utilize conventional hydraulic double acting single end cylinders with the cylinders oriented perpendicular to the flat deck of the central deck21of the trailer20. The selectably reciprocable rods of the jacks44extend downwardly. The jacks44are similar to each other and generally consist of a conventional hollow right circular cylindrical body of revolution45having a main bore diameter, a blind end at an upper end, and a reduced bore diameter gland at the lower end.

Each jack body45has a radially outwardly extending cylinder mounting bracket46on one side. A right circular cylindrical jack cylinder rod47having an upset transverse cylindrical piston head at its upper end and a male threaded distal portion at its lower end is deployed in the cylinder body45. The piston head and the rod shank respectively seal to the main bore and the gland of the cylinder body. A foot plate assembly48having from its upper end a female socket threadedly engaged with the male thread of the rod47, a pivoting hinge with a foot plate pivot pin49, and a rectangular transverse foot plate is located at the bottom of each jack44. The axis of the foot plate pivot pin49is horizontal and is perpendicular to the longitudinal midplane of the trailer20.

Each jack44is attached to a rear inner pivot plate30in its vertical position inboard of and extending forward of the forward vertical edge of the inner pivot plate30. The positioning of the jacks44is such that their foot plates will not interfere with the forward deck of the central deck21of the trailer20when the foot plates48of the jacks are raised or lowered.

The forward deck54of the trailer20is a short flat section which is somewhat narrower than the rest of the trailer. The forward deck54of the trailer has a conventional kingpin extending downwardly on the underside of the forward deck. The kingpin55attachment is transverse to the upper surface of the forward deck and is located on the longitudinal midplane of the trailer20near the forward deck of the forward deck. The kingpin55is configured to be selectably latched and unlatched from the fifth wheel12of the tractor11so that the trailer20can be towed readily. The nature of the kingpin55to fifth wheel12attachment is such that it can tolerate a reasonably large amount of angular misalignment while still transmitting towing and braking forces between the trailer20and the tractor11. The kingpin55and the upper surface of the forward deck54are structurally interconnected by large longitudinal beams and smaller transverse beams.

Towards its rear end, the forward deck54is connected there to a pair of identical forward pivot plates56. One forward pivot plate56is attached by lapping welding the pivot plate56onto each outboard side of the forward deck54. As can be seen inFIGS. 4,5, and9, the forward pivot plates56extend to the rear and below the main portion of the forward deck54.

The lateral positioning of the pivot plates25,30, and56relative to the longitudinal centerline of the trailer20is such that each forward pivot plate56of the forward deck54will have a loose slip fit between a rear outboard pivot plate25and a rear inboard pivot plate30of the central deck21when the two portions of the trailer are comated with their pivot holes26,31, and57placed in a coaxial position and the longitudinal centerlines of the forward deck54and the central deck21of the trailer aligned.

Referring toFIG. 9, the configuration of the forward pivot plates56is as follows moving counterclockwise from the lower rear corner of the plates. Edge84is an arcuate surface extending upwardly and a forward direction and covering an arc length of more than 90°. The upper end of the arcuate edge84is located vertically above the axis of the arcuate surface. Horizontal edge85is coplanar with the upper deck surface of the forward deck54and extends forward past the rear transverse end of the forward deck surface. Vertical edge86extends from the upper side to the lower side of the forward deck54. First inclined edge87slopes downwardly in a rearward direction, where it intersects second inclined edge88.

The second inclined edge88slopes slightly upwardly in the rearward direction until it intersects the arcuate edge84. The intersection of the first87and second88inclined edges is radiused, as is the intersection of the second inclined edge88and the arcuate edge84. Typically rectangular and triangular plate segments are used to form hollow triangular prismatic transitions between the vertical edges86of the two forward pivot plates56and the sides of the forward deck54.

A large diameter pivot pin through hole57is aligned with the axis of the arcuate edge84of the forward pivot plates56. The diameter of the pivot pin holes57in the forward pin plates is substantially the same as that of the pivot pin holes26and31of the rear outer25and rear inner30pivot plates.

Referring toFIG. 9, a first position locking pin hole58in the forward pivot plate56is located vertically at radius R above the pivot pin hole57, and a second position locking pin hole59is located at radius R from the pivot pin hole57clockwise from position locking pin hole58by angle ΦB. The first58and second59position locking pin holes of the forward pivot plate56have about the same diameter as that of the position locking pin holes27,28of the rear outer pivot plates25and the position locking pin holes32,33of the rear inner pivot plates30.

At assembly, the forward pivot plate56is positioned between the rear pivot plates25and30with the pivot pin holes26,31, and57coaxially aligned and normal to the longitudinal midplane of the trailer20. Furthermore, the first position locking pin holes25and32of the rear pivot plates25and30are coaxially aligned with the first position locking pin hole58of the forward pivot plate56, and the second position locking pin holes28and33of the rear pivot plates25and30are coaxially aligned with the second position locking pin hole59of the forward pivot plate56.

Two pivot pins36and two position locking pins38are used to join the elements of the two altitude adjustment mechanisms24and thus the forward deck54to the central deck21of the trailer20. The pivot pins36are headed on a first end and generally have a slight taper on the second end. The length of the right circular cylindrical central portion of the pivot pins36is sufficient to extend through and approximately one inch beyond each set of three interleaved pivot plates25,30,56, and the diameter of the pivot pins36is such that they are a slip fit to the pivot pin holes26,31, and57.

Typically, transverse diametrical keeper pins holes40are offset axially outwardly from the head of the pivot pins36. The pivot pins36are stabbed through the coaxial pivot pin holes26,57, and31at assembly of the trailer20so that the transverse inner shoulders of the headed pivot pins36abut a rear outboard pivot plate surface. Headed elongated cylindrical pivot pin keepers37are inserted through the keeper pin holes40to retain the pivot pins36in place after assembly. Often headed bolts with lock nuts are used for this purpose. Following the insertion of the pivot pins and their keepers37, the central deck section21and the forward deck section54of the trailer20are hinged together on a horizontal axis transverse to the longitudinal midplane of the trailer.

The two position locking pins38are substantially similar to the pivot pins36, with the exception that the diameter of the central cylindrical section of the position locking pins38is a slip fit both to the first position locking pin holes27,32,58and the second position locking pin holes28,33,59position locking pin holes. Position locking pin keepers39, used for the position locking pins38, are similar to the keeper pins37used with the pivot pins36with the exception that the keeper pins39are shorter, since the diameter of the position locking pins38is less than that of the pivot pins36. The position locking pin keepers39are inserted into diametrical cross holes41in the exposed nonheaded ends of the position locking pins38to provide pin retention.

When the trailer has both its pivot pins36installed as described above and its position locking pins38installed in either the coaxial position locking pin holes27,32,58or the coaxial position locking pin holes28,33,59, the trailer20has its central deck section21structurally attached in a rigid and safe load bearing configuration. Either of the two described configurations is structurally competent to transport a heavy trailer cargo70on both highways and unimproved roads.

OPERATION OF THE INVENTION

To complete assembly of the trailer20, the position locking pins38with their position locking pin keepers39are installed in either the coaxial position locking pin holes27,32, and58or alternatively in the coaxial position locking pin holes28,33, and59. For the purpose of example, it is assumed herein that the position locking pins are preinstalled in the coaxial first position locking pin holes27and32of the central deck portion21and the mutually coaxial first position locking pin holes58of the forward deck54portion of the trailer20. The result is the first configuration of the trailer20shown in bothFIGS. 1 and 2, with the jacks44fully retracted. This first configuration of the trailer20provides both an acceptable road clearance and a minimal practical load height for highway use.

In order to increase the road clearance for the trailer20from that shown inFIGS. 1 and 2, the first step is to extend the jacks44until they bear fully on the surface of the roadway, as is shown inFIG. 3. When the jacks44are then extended sufficiently further, the transverse loadings on the position locking pins38are reduced sufficiently to permit their extraction after the removal of the position locking pin keepers39. Following extraction of the position locking pins38, the jacks are extended still further until the second position locking pin holes28,33, and59are brought into axial alignment, as shown inFIG. 6.

The change of alignment from the first position shown inFIGS. 1 and 2to that ofFIG. 6is effected by elevating both the forward deck of the central deck21and the rear portion of the forward deck54, which are still pinned together by the pivot pins36. At this point, the position locking pins38are then fully inserted into the now aligned and coaxial second position locking pin holes28,33,59and individually retained by their respective position locking pin keepers39engaged in the holes41of the locking pins38. The position locking pins38are shown in their installed second position inFIG. 6.

To transition from the arrangement shown inFIG. 6to the completed off-highway position shown inFIG. 7all that is necessary is to fully retract the jacks44so that they do not extend below the bottom of the central deck21of the trailer20. When the trailer is elevated as is shown inFIG. 7, the center portion of the length of the trailer20located between the fifth wheel12and the rear axles52is sufficiently elevated that it will clear high spots on most unimproved roads. The resulting improved road clearance allows the low boy trailer to be brought into and removed from the majority of most remote field locations.

Adjusting the trailer from the higher ground clearance configuration to the lower ground clearance configuration, the operator reverses the procedure for transitioning from the low ground clearance configuration ofFIG. 2to the improved ground clearance configuration ofFIG. 7.

ADVANTAGES OF THE INVENTION

The provision of the selectably lockable articulated transverse axis joint intermediate to the length of the low boy trailer of the present invention readily permits adjusting the ground clearance of the trailer to handle different road conditions. The selectable locking of the altitude adjustment mechanism24is accomplished easily with the use of the position locking pins38.

Fabrication costs for the altitude adjustment mechanism are low. The cost of the simple mechanical components is relatively low, and maintenance costs are minimal. The pinned connection is inherently robust while providing sufficient stiffness and strength to ensure long term reliability. Equipment inspection is quite simple.

Operator training is relatively simple and equipment inspection is basic. There are numerous advantages of being able to provide a practical maximum load height when operating on highways with vertical height limitations, while still being able to selectably and easily increase the road clearance of the critical central section of the trailer.

Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. As may be understood readily by those skilled in the art, certain variations in the structure of the present invention may be made without departing from the spirit of the invention. For instance, mechanical rather than hydraulic jacks could be used to raise and lower the trailer. The position locking pins could be made so that they can be withdrawn and engaged using screw threads to reciprocate the pins out of and into full engagement with the position locking pin holes. These and other minor changes can be made without departing from the spirit of the invention.