Abstract:
A system where a trailer/dolly ( 10 ) is lifted from the ground (by means of block and tackle, hydraulic rams, etc.) so as to locate beneath, or nest within, the chassis or sub-frame ( 12 ) of a vehicle. When it is to be used the trailer/dolly is either coupled under a vehicle or trailer as a dolly only or it is lowered and moved rearwardly of the vehicle so it can be towed behind the vehicle using hitch ( 40 ). The chassis ( 14 ) of the trailer/dolly is in the form of a rectangular frame which can be enlarged in size by telescopic movements of members ( 20 A B;  22 A, B etc.). A large number of small wheels ( 16 A, B;  18 A, B etc.) may be provided on sprung stub-axles.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a trailer or dolly and relates particularly, though not exclusively, to a stowable trailer or dolly system. 
     BACKGROUND OF THE INVENTION 
     Trailer or caravan axles are vulnerable to breakages, particularly under extended fatigue conditions which are experienced when a trailer or caravan is trailed large distances. When the axle breakage occurs in a remote location, which is often the case, the trailer or caravan must be abandoned and a tow truck taken to the trailer or caravan so that it can be trailed on its unbroken axle. Alternatively, for a single axle trailer or caravan, repairs to the broken axle must be made at the site of the breakage. In any event it is particularly inconvenient and expensive to repair the axle breakage. 
     Australian patent No. 521004 relates to a carry towing trailer known as a MOBITOW. The MOBITOW is essentially a dolly designed to be hitched to and drawn by a towing vehicle. The MOBITOW is configured to “piggyback” the front or rear wheels of an immobilised motor vehicle. The MOBITOW includes a chassis which can be moved adjacent the ground and the front or rear wheels of the immobilised vehicle then drawn onto cradles provided on the chassis. The chassis is then raised to a trailerable position above the ground and the immobilised vehicle towed as required. Although the MOBITOW provides a relatively convenient means for towing a vehicle it still does not overcome the problems identified in the preceding paragraph. 
     SUMMARY OF THE INVENTION 
     An intention of the present invention is to provide a trailer or dolly which can be stowed beneath or within a vehicle chassis or sub-frame. 
     According to one aspect of the present invention there is provided a trailer or dolly comprising: 
     a chassis for carrying a load, said chassis adapted to be towed behind a vehicle or another trailer; and 
     a plurality of ground engaging wheels rotatably mounted to the chassis; 
     said chassis expandable to an operable configuration and contractible to a compact configuration, whereby in use, the trailer or dolly can be towed behind the vehicle or other trailer in a drawn position when the chassis is in the operable configuration, or the trailer or dolly can be stored beneath or within the vehicle or other trailer in a stored position when the chassis is in the compact configuration. 
     Preferably the chassis is adapted to be towed behind the vehicle or other trailer by a substantially horizontal articulated connection. 
     According to another aspect of the present invention there is provided a stowable trailer or dolly system comprising: 
     a chassis for carrying a load, said chassis adapted to be towed behind a vehicle or another trailer; and 
     a plurality of ground engaging wheels rotatably mounted to the chassis; and 
     means for locating the trailer or dolly chassis beneath or within the vehicle or other trailer, said means adapted to engage the chassis and move it into the stored position when the chassis is in the compact configuration, 
     said chassis expandable to an operable configuration and contractible to a compact configuration whereby in use, the trailer or dolly can be towed behind the vehicle or other trailer in a drawn position when the chassis is in the operable configuration, or the trailer or dolly can be stored beneath or within the vehicle or other trailer in a stored position when the chassis is in the compact configuration. 
     Typically, said means for locating the trailer or dolly chassis beneath or within the vehicle chassis or sub-frame includes a block and tackle arrangement coupled between the vehicle and the trailer or dolly chassis so as to permit lifting of the trailer or dolly into the stored position. More typically, the block and tackle arrangement comprises one or more blocks including a ratchet block together with a chain or rope designed to operatively cooperate therewith. 
     Alternatively, said means includes one or more rails movably coupled to the vehicle chassis or sub-frame, said rails designed to move adjacent the ground and thereafter engage the trailer or dolly chassis and/or the wheels so that the trailer or dolly can be raised into the stored position. 
     In yet another embodiment, said means include one or more hydraulic rams connected to the vehicle chassis or sub-frame and the trailer or dolly chassis, respectively, said rams being designed to raise and lower the trailer or dolly into the stored or trailed position. 
     Typically, the trailer or dolly chassis includes a pair of elongate transverse and longitudinal members interconnected so as to form a generally oblong or square shaped chassis frame. More typically, the pair of transverse and/or longitudinal members are of a telescopic construction so that said members in a retracted position allow the trailer or dolly to be accommodated beneath or within the vehicle chassis or sub-frame in the stored position. 
     Preferably, the trailer or dolly chassis also includes a central elongate member opposing ends thereof being connected between the pair of transverse members. More preferably, the central member is also of a telescopic construction so that extension and retraction of the central member can occur together with a corresponding movement in the pair of longitudinal members. 
     Preferably, the trailer or dolly farther comprises a draw bar connected to the trailer or dolly chassis, a towing hitch being mounted to an end of the draw bar so as to permit coupling of the trailer or dolly to a tow bar of the vehicle with the trailer or dolly in the drawn position. 
     Typically, the draw bar is telescopically coupled to the trailer or dolly chassis so that in an extended position the trailer or dolly can be hitched to the vehicle in the drawn position, and in a retracted position the trailer or dolly can be stowed beneath or within the vehicle chassis or sub-frame in the stored position. 
     Alternatively, the draw bar is detachably coupled to the trailer or dolly chassis so that with the draw bar detached from said chassis the trailer or dolly can be accommodated by the vehicle in the stored position. 
     Preferably, the wheels are each of a relatively small diameter wherein the trailer or dolly chassis can be located in the stored position with adequate clearance between said wheels and the ground. Generally, the diameter of the wheels is from between 200 to 500 mm. 
     Typically, the wheels are mounted to the trailer or dolly chassis via a stub-axle for each of said wheels. More typically, each of the stub-axles is retractably coupled to the trailer or dolly chassis so that the wheels car be located inwardly or outwardly of the chassis. 
     Typically, the stub-axles are connected to a solid or swivel stub-axle mount of the trailer or dolly chassis, the stub-axle mount being disposed relative to said chassis so as to provide adequate clearance between the ground engaging wheels and the ground with the trailer or dolly in the scored position. More typically, the trailer or dolly includes a suspension system, wherein the suspension system is in the form of wheels, tyres, stub-axles or stub-axle mounts which are adapted to absorb and/or cushion any ground impact forces. 
     Typically, the trailer or dolly chassis is designed to carry a front or rear portion of a carriage, the rear or front wheels, respectively, of the carriage being trailed along the ground. In this example the carriage may include a caravan having a broken or damaged front or rear axle. 
     Alternatively, the trailer or dolly chassis is constructed in the form of a box trailer having a tray mounted to the chassis frame, the tray being designed to carry the load. 
     In one embodiment, the trailer or dolly is constructed of an aluminium alloy being relatively lightweight. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to achieve a better understanding of the nature of the present invention a possible embodiment of a trailer or dolly will now be described in some detail, by way of example only, with reference to the accompanying drawings in which: 
     FIG. 1 is a perspective view of a trailer or dolly stowed beneath or within a vehicle chassis; 
     FIG. 2 is a plan view of the trailer or dolly shown in FIG. 1 with the draw bar in an extended position; 
     FIG. 2A is an enlargement of a portion of FIG. 2, with two of the wheels removed; 
     FIG. 3 is a side elevational view of the trailer or dolly illustrated in FIG. 2; 
     FIG. 4 is a side elevational view of the trailer or dolly depicted in FIGS. 2 and 3 with the draw bar in a retracted position; and 
     FIG. 5 is a side elevational view of the trailer or dolly having both the chassis and the draw bar extended; 
     FIG. 5A is the trailer or dolly of FIG. 5 carrying a vehicle; 
     FIG. 5B is the trailer or dolly of FIG. 5 with a tray for carrying a vehicle; 
     FIG. 6A is a perspective view of the trailer or dolly ready for stowing beneath or within the vehicle chassis of FIG. 1, with a block and tackle arrangement coupled between the vehicle chassis and trailer or dolly chassis; 
     FIG. 6B is a perspective view of the trailer or dolly with a set of rails pivotally coupled beneath or within the vehicle chassis of FIG. 1, and ready to engage the trailer or dolly chassis; and 
     FIG. 6C is a perspective view of the trailer or dolly with a set of hydraulic rams pivotally coupled beneath or within the vehicle chassis of FIG. 1, and ready to engage the trailer or dolly chassis. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     As shown in FIG. 1 there is a trailer or dolly shown generally as  10  mounted beneath or within a vehicle chassis  12 . 
     The trailer or dolly  10  comprises a trailer or dolly chassis  14  being designed to carry a load (not shown), and two (2) pairs of ground engaging wheels  16 A/B and  18 A/B respectively which are rotatably mounted to the trailer or dolly chassis  14 . The trailer or dolly  10  illustrated in FIG. 1 is in a stored position. 
     The trailer or dolly  10  depicted in FIG. 2 has been removed from beneath or within the vehicle chassis  12  into a drawn position in preparation for towing. The trailer or dolly chassis  14  includes a pair of opposing elongate transverse members  20 A,  20 B and a pair of opposing elongate longitudinal members  22 A,  22 B. The transverse and longitudinal members  20 ,  22  are interconnected so as to form the rectangular-shaped dolly chassis  14 . 
     Each of the elongate members  22 ,  24  is of a telescopic construction. That is, the longitudinal members  22 A/B each include a pair of abutting longitudinal tubular members  26 A/B which are slidably movable relative to an internal sleeve  28  which is received therein. The transverse members  20 A/B each consist of three (3) transverse tubular members  30 A/B/C adjacent and abutting tubular members  30 A/B and  30 B/C having an internal transverse sleeve  32  about which they are slidably received. 
     The trailer or dolly chassis  14  also includes a central elongate member  34  having opposing ends connected between and extending perpendicular to the pair of transverse members  20 A/B. The central member  34  is also of a telescopic construction so that extension and retraction of the central member  34  can occur together with a corresponding movement in the pair of longitudinal members  22 A/B. The trailer dolly or chassis  14  has a pair of intermediate elongate members  36 A/B opposing ends thereof being connected to opposing transverse tubular members  30 A and  30 C, respectively. The intermediate members  36 A/B are located between and extend generally parallel to the central member  34  and each of the longitudinal members  22 A/B. 
     The trailer or dolly  10  further comprises a draw bar  38  connected to the trailer or dolly chassis  14 . A towing hitch  40  is mounted to an end of the draw bar  38  so that the trailer or dolly  10  can be hitched to a tow bat (not shown) of a vehicle with the trailer or dolly  10  in a drawn position. In this embodiment, the draw bar  38  consists of three (3) telescopic sections  42 A/B/C being slidably received within and thus movable relative to each other. The telescopic section  42 C is slidably received within the central member  34 . The telescopic draw bar  38  is shown in a fully retracted and a fully extended position in FIGS. 1 and 2, respectively. 
     As best shown in FIG. 3, the trailer or dolly  10  includes a pair of draw bar locking pins  44 ,  46  designed to lock adjacent telescopic sections  42 A and  42 B together with telescopic section  42 C relative to the central member  34 . The locking pins  44 ,  46  each pass through both the adjacent telescopic sections  42 A/B and the telescopic section  42 C and central member  34 , respectively. A set of chassis locking pins including longitudinal member locking pins  48  and  50  are configured to securely lock both the telescopic transverse and longitudinal members  20 A/B and  22 A/B whilst the trailer or dolly  10  is in use. The chassis frame locking pins including  48  and  50  pass through both the tubular members and their corresponding internal sleeve, for example longitudinal tubular member  26 A and longitudinal sleeve  28 . 
     As best illustrated in FIG. 1, the trailer or dolly includes twelve (12) stub axle mounts one of which is shown as  52 , another of which is shown as  64  in FIG. 5A, each being mounted at various locations beneath the trailer or dolly chassis  14 . Three (3) of the stub axle mounts  52 ′ are mounted to each of the longitudinal and intermediate members  22 A/B and  36 A/B. An additional three stub axles may be mounted on the central member  34 . A stub axle  60  in FIG. 2A of each of the wheels  16 ,  18  can be retractably inserted through one of the mounts  52 . Thus, the wheels  16 ,  18  can be selectively located at anyone of thirty (30) positions. 
     FIG. 2 illustrates only sixteen (16) of the possible locations. A further eight (8) locations are possible due to the middle stub mounts between the stub mounts used in FIG.  2 . In addition, a further six (6) locations are possible, three on either side of the central member  34 . In FIG. 2A the wheel  16 C mounted by extended stub axle  60 . Stub axle  62  is shown retracted. 
     The pair of ground engaging wheels  16 ,  18  in FIGS. 3 and 4 are located in the hatched positions as depicted in FIG.  2 . In this example, the wheels  16 ,  18  are conveniently located inwardly of the trailer or dolly chassis  14  so that the trailer or dolly  10  can be located within the vehicle chassis  12  in the stored position. Similarly, the stub axles of the wheels  16 ,  18  shown in FIG. 1 are mounted to the central stub axle mounts  52  inwardly of the trailer or dolly chassis  14 . 
     The trailer or dolly chassis  14  in FIGS. 3 and 4 is shown in a retracted position. Locking pins  48  and  50  rigidly secure longitudinal tubular members  26 A/B to the longitudinal internal sleeve  28 . However, as shown in FIG. 5, the trailer or dolly chassis  14  may be extended whereupon one or both of the longitudinal tubular members  26 A/B is telescopically slid over the internal sleeve  28  so as to extend the effective length of the trailer or dolly chassis  14 . The locking pins  48 ,  50  secure the longitudinal tubular members  26 A/B relative to the internal sleeve  28  so as to fix the chassis  14  in this position. The frontmost pair of wheels  16 A,  18 A are then moved to the intermediate stub axle mounts  52 . It will be appreciated that the trailer or dolly in its drawn position, such as that illustrated in FIGS. 2,  3 , and  5 , may take various configurations including variations in the width and length of the trailer or dolly chassis  14  and the various positions of the ground engaging wheels  16 ,  18 . 
     The trailer or dolly  10  of FIGS. 2 and 5 includes a turntable  56  pivotally mounted to the central member  34 . The turntable  56  is designed to support a front or rear axle of an immobilised conveyance, including a vehicle (as shown in FIG.  5 A), a caravan and a trailer (not depicted) requiring towing. The trailer or dolly  10  may include other support means for carrying a load. For example, as shown in FIG. 5B, a tray  70  may be mounted to an upper surface of the trailer or dolly chassis  14  wherein the trailer or dolly  10  represents a box-type trailer. The tray is preferably collapsible and includes sides. It is preferable that the trailer or dolly  10  is constructed of relatively lightweight materials. For example, the trailer or dolly chassis  14  may be constructed of an aluminum alloy which is also weldable and thus appropriate for fabrication purposes. 
     In FIGS. 6A,  6 B and  6 C, a trailer or dolly as broadly disclosed above is shown together with means for locating the trailer or dolly beneath or within a vehicle. The means for locating the trailer or dolly could include but is not limited to the following arrangements: 
     (i) a block and tackle arrangement  74  coupled between the vehicle chassis  12  and the trailer or dolly chassis  14  so as to permit lifting of the trailer or dolly  10  into the stored position; 
     (ii) one or more rails  76  slidably and/or pivotally coupled to the vehicle chassis  12  so that the rails can be moved adjacent the ground and thereafter engage the trailer or dolly chassis  14  and/or the ground engaging wheels  16 ,  18  so that the trailer or dolly  10  can be raised into the” stored position; and 
     (iii) one or more hydraulic rams  78  connected at opposing ends to the vehicle chassis  12  and the trailer or dolly chassis  14 , respectively, the rams being designed to raise the trailer or dolly  10  into the stored position. 
     Now that a possible embodiment of the present invention has been described in some detail it will be apparent to those skilled in the relevant art that the trailer or dolly described has at least the following advantages: 
     (i) the trailer or dolly can be conveniently stowed beneath or within a vehicle chassis or sub frame; and 
     (ii) the stowable trailer or dolly system allows for storage of the trailer or dolly beneath or within a vehicle chassis or sub-frame with relative ease. 
     It will be apparent to those skilled in the relevant art that the present invention is not limited to the examples described but rather may extend to other variations/modifications not specifically described. For example, the draw bar and/or ground engaging wheels may be fully detachable from the trailer or dolly chassis. The trailer or dolly chassis may not in fact be extendable but rather by the nature of its construction be of such a size that it can be located beneath or within a vehicle chassis or sub-frame. Furthermore, the trailer or dolly is not to be limited to the specific construction described and may, for example, not include the longitudinal and/or transverse members. 
     It should be understood by a skilled addressee that if a vehicle does not have a chassis or the chassis is not adapted to be able to locate the trailer or dolly beneath or within, then a sub-frame may be attached to the vehicle which is adapted to locate the trailer or dolly beneath or within the sub-frame. The term sub-frame is to be construed to include this meaning without limiting its normal meaning. 
     All such variations and modifications are to be considered within the scope of the present invention the nature of which is to be determined from the foregoing description.