Abstract:
A unitized hydraulic suspension system for a tandem front and back two-axle group comprises two pivoting arms, each for supporting one of the two axles, arranged on opposite sides of a common rigid hanger. Each arm is attached to one end of a respective cylinder the other end of which cylinder is attached to the common hanger. The unitized hydraulic suspension simplifies the use of hydraulic suspension in dual laning heavy haul applications by the provision of a slide assembly in which unitized hydraulic suspensions are slidably mounted so as to be extendible or retractable in relation to one another.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to heavy haul multi-axle transport vehicles. In particular, this invention relates to suspension systems for such vehicles. 
       BACKGROUND OF THE INVENTION 
       [0002]    Known suspension systems typically used in North America for multi-axle heavy haul trailer applications include air ride suspensions, leaf spring-based systems and walking beam systems. 
         [0003]      FIGS. 1 and 2  show another type of prior art suspension system, commonly known as a pendulum type hydraulic suspension, and that is sometimes used in heavy haul applications. In a pendulum type hydraulic suspension, the axle  10  pivots about a lower arm  12  that is in turn pivoted in relation to an upper arm  14  about a pivot pin  16 . The upper arm  14  depends from a turntable plate  18  that rotates about a centre axis allowing the suspension assembly and its captive axle to rotate in relation to the frame of the trailer. A hydraulic cylinder  20  extends from the turntable plate  18  to the lower arm  12 , the cylinder being located between the pivot pin  16  and the axle  10 . Such a prior art system is also exemplified in FIG. 4 of U.S. Pat. No. 6,942,232 to McGhie. 
         [0004]    In multi-axle trailers, each axle is independently suspended by its own pendulum type suspension. Equalization between the axles of an axle group tends to rely on fluid exchanges between the cylinders of the independent suspensions of the axle group. As one of the axles goes over a bump, the cylinder is compressed and the fluid moves to one or more other cylinders to support the load on the other axles. Equalization in pendulum type hydraulic suspensions can be more effective than in walking beam or air ride suspensions. 
         [0005]    A disadvantage of this arrangement is that the location of the cylinder, being attached between the pivot point (the pivot pin) and the axle, does not provide the maximum possible mechanical advantage. The lack of an ideal mechanical advantage is compensated by providing more powerful cylinders. On the other hand, the system offers the advantage of providing the maximum effect for a minimum amount of piston stroke, since the cylinder is relatively close to the pivot point. 
         [0006]    Independent hydraulic suspensions are sometimes used in heavy haul applications but not frequently so. However, they do offer the flexibility that is often needed in designing heavy haul applications that require various spacing between axles and axle groups. 
         [0007]    Some jurisdictions, such as in the United States, allow what is known as “dual lane loading” for heavy haul vehicles. Dual lane loading allows the load to be spread over two lanes of a road using axles that extend across up to two lanes. This effectively increases the total weight allowance. In the prior art, dual lane loading is sometimes achieved by using walking beam types of suspensions and hydraulically telescoping the axles outward or inward as needed. When necessary, for example to cross a narrow bridge, the axles are telescoped inward to a narrower configuration and are brought back out for continued travel. 
         [0008]    The applicant understands that telescoping of pendulum type independent hydraulic suspensions to achieve dual lane loading has been considered by some. However, telescoping the various hydraulic suspensions along with their captive axles and coordinating their movement is difficult. The practical resolution to the problem has been to provide systems wherein the hydraulic suspensions are unbolted, spacers or connectors are added or removed and the suspensions are re-bolted into a narrower or a wider configuration as the case may be. Such an approach is also exemplified in US Patent Publication No. 2009/0273159 (Sutton). It will be appreciated that that approach is unwieldy and time consuming. 
         [0009]    It is therefore an object of this invention to providea heavy haul vehicle that uses pendulum type hydraulic suspensions that is better suited for use with a telescoping system for accommodating dual lane loading applications. 
         [0010]    These and other objects of the invention will be better understood by reference to the detailed description of the preferred embodiment which follows. Note that not all of the objects are necessarily met by all embodiments of the invention described below or by the invention defined by each of the claims. 
       SUMMARY OF THE INVENTION 
       [0011]    In one aspect, the invention is a unitized hydraulic suspension system for a two-axle tandem (front and back) axle group used in a heavy-haul transport vehicle. Two pivoting arms, each for supporting one of the two axles, are arranged on opposite sides of a common hanger structure. Each of the arms is attached to one end of a respective hydraulic cylinder the other end of which cylinder is attached to the common hanger in an opposed front and back arrangement across the hanger. 
         [0012]    In another aspect, the hanger comprises a pivot mounting structure on which the pivoting arms are pivotally mounted and the front and back arrangement may be defined in relation to a vertical central axis of the pivot mounting structure. 
         [0013]    In a further aspect, the pivot arms define pivot axes and the top ends of the two cylinders are secured to a common rigid structure above the pivot axes. 
         [0014]    In another aspect, the invention comprises a dual-laning hydraulic suspension system. The system comprises at least two side by side unitized hydraulic suspension systems slidably mounted in relation to one another. 
         [0015]    In one aspect, the unitized hydraulic suspension systems are mounted in relation to a slide assembly enabling the unitized hydraulic suspension systems along with their supported axles to be selectively repositioned in a retracted or an extended relationship to each other by sliding the unitized suspension systems in relation to the slide assembly. 
         [0016]    In a further aspect of the dual laning hydraulic suspension system, each of said at least two tandem hydraulic suspension systems is mounted to a mounting beam structure. The slide assembly comprises a slide box assembly and the mounting beam structure is engaged within the slide box assembly. At least one hydraulic cylinder actuates sliding movement of the mounting beam structures in relation to the slide box assembly. 
         [0017]    The foregoing was intended as a summary only and of only some of the aspects of the invention. It was not intended to define the limits or requirements of the invention. Other aspects of the invention will be appreciated by reference to the detailed description of the preferred embodiments. Moreover, this summary should be read as though the claims were incorporated herein for completeness. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The invention will be described by reference to the detailed description of the preferred embodiment and to the drawings thereof in which: 
           [0019]      FIG. 1  is a perspective view of a prior art hydraulic suspension; 
           [0020]      FIG. 2  is a side elevation of the suspension of  FIG. 1 ; 
           [0021]      FIG. 3  is a perspective view of the preferred embodiment of a unitized tandem hydraulic suspension according to the invention, with the axles and wheels removed for clarity; 
           [0022]      FIG. 3A  is a perspective view of the suspension of  FIG. 3 , but including axles and one of the two sets of four wheels; 
           [0023]      FIG. 4  is a bottom and side perspective view of the suspension of  FIG. 3 ; 
           [0024]      FIG. 5  is a perspective view of the suspension of  FIG. 3  with the axle mount removed to show an extended portion of the lower arm; 
           [0025]      FIG. 6  is a top and side perspective view of the hanger member and the pivot mounting member of the preferred embodiment; 
           [0026]      FIG. 7  is a perspective view of the pivot mounting member of the preferred embodiment; 
           [0027]      FIG. 8  is a top perspective view of a support arm of the preferred embodiment; 
           [0028]      FIG. 9  is a perspective view of two unitized hydraulic suspensions according to an alternative embodiment of the invention, in which the mounting beam structures for each suspension and the slide box assembly for receiving the two mounting beam structures are omitted; 
           [0029]      FIG. 10  is a front elevation of the alternative embodiment of the invention showing two side by side unitized hydraulic suspensions, part of their respective mounting beam structures and the slide box assembly; 
           [0030]      FIG. 10A  is a view similar to  FIG. 10  but including the turntable and coupler for steering the assembly of the alternative embodiment; 
           [0031]      FIG. 11  is a front elevation of the system of  FIG. 10  but wherein the wheels, axles and the slide box assembly have been omitted; 
           [0032]      FIG. 12  is a side elevation of one of the unitized hydraulic suspensions of the alternative embodiment; 
           [0033]      FIG. 13  is a slightly perspective view of the suspension of  FIG. 12  further showing the rollers on the mounting beam structure of the alternative embodiment; 
           [0034]      FIG. 14  is a side elevation of one of the mounting beam structures of the alternative embodiment; 
           [0035]      FIG. 15  is a bottom perspective view of the mounting beam structure of  FIG. 14 ; 
           [0036]      FIG. 16  is an end perspective view of the mounting beam structure of  FIG. 14 ; 
           [0037]      FIG. 17  is a perspective view of the slide box assembly of the alternative embodiment; 
           [0038]      FIG. 18  is a bottom perspective view of the slide box assembly of  FIG. 17 ; 
           [0039]      FIG. 19  is a side perspective view of the slide box assembly, the two mounting beam structures and the telescoping cylinders of the alternative embodiment, with the viewing sides of the slide box assembly and of one of the mounting beam structures omitted; 
           [0040]      FIG. 20  is a top view of the slide box assembly, the mounting beam structures, the turntable and the coupler of the alternative embodiment; and, 
           [0041]      FIG. 21  is a front view of the structures of  FIG. 20 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0042]      FIGS. 3 and 3A  illustrate the unitized hydraulic suspension system  30  according to a preferred embodiment.  FIG. 3A  is a view similar to that of  FIG. 3  but shows front  32  and rear  34  axles and four of the wheels  36 ,  37 ,  38  and  39 . 
         [0043]    The front axle  32  is supported by a front support arm  44  that is pivoted about a pivot mounting member  46 . A front pivot pin  48  defines a forward pivot axis  49  for the front support arm  44 . A rear axle  34  is supported by a rear support arm  50  that is also pivoted about the same pivot mounting member  46 . A rearward pivot pin  52  defines a rear pivot axis  54  for the rear support arm  50 . Each of the front and rear support arms  44 ,  50  includes an axle mount comprising in this embodiment axle saddle brackets  56 ,  58  and U-bolts  60 ,  61 ,  62  and  63  for retaining the axles  32 ,  34  on the support arms  44 ,  50 . 
         [0044]    The suspension system supports a tandem axle arrangement with a front axle  32  leading a rear axle  34  (in this specification and in the claims, “tandem” refers to a front and back or fore and aft arrangement). The suspension system is used in a multi-axle heavy haul transport vehicle that will typically include a number of unitized hydraulic tandem suspension systems according to the invention. 
         [0045]    A rigid hanger member  64  extends above the pivot mounting member  46 , generally along a central vertical axis  66  of the pivot mounting member  46 . It is contemplated that in some embodiments, the pivot mounting member  46  and the rigid hanger  64  may consist of a unitary construction. However in the preferred embodiment, the hanger  64  is a separately definable structure but that is permanently secured to the pivot mounting member  46  and the hanger member  64  may itself comprise several plates and cross members as discussed in more detail below. 
         [0046]    A front hydraulic cylinder  90  has a first end  92  secured at a point at one side of the hanger  64  and a rear hydraulic cylinder  94  has a first end  96  secured at the opposite side of the hanger  64 . The first ends  92 ,  96  of both the front and rear cylinders  90 ,  94  are attached to the same hanger  64 . In the preferred embodiment, the first ends  92 ,  96  front and rear hydraulic cylinders  90 ,  94  are attached by cylinder pins  93 ,  95  to cylinder lug brackets  97 ,  99  that are integrated into the rigid hanger structure  64 . The front and rear cylinders are therefore attached at opposed front and back positions  102 ,  104  in relation to the vertical central axis  66  of the pivot mounting member  46 . The upper ends  92 ,  96  of the front and rear cylinders are attached at points above the pivot axes  49 ,  54  of the support arms. 
         [0047]    The piston of the front cylinder  90  is attached to the front support arm  44  while the piston of the rear cylinder  94  is attached to the rear support arm  50 . 
         [0048]    In this arrangement, the front cylinder  90  extends forwardly and downwardly from its attachment point to the rigid hanger  64  to connect to the front support arm  44  while the rear cylinder  94  extends rearwardly and downwardly from its attachment point to the rigid hanger to connect to the rear support arm  50 . 
         [0049]    Referring to  FIG. 6 , the hanger structure comprises two end plates  118 ,  120 , two side plates  122 ,  124  and two spaced parallel cylinder lug brackets  97 ,  99  extending across the two end plates and that are attached to one another by the cylinder pins  93 ,  95 . 
         [0050]    The pivot mounting member  46  is shown in isolation in  FIG. 7 . It comprises two end brackets  101 .  103  and a spanning brace  107 . The spanning brace  107  is disposed between four apertures  109 ,  111 ,  113  and  115  in the end plates, those apertures being sized to receive the pivot pins  48 ,  52 . 
         [0051]    Referring to  FIG. 8 , each of the support arms comprises two side wall plates  126 ,  128 , a bottom plate  130  and a diagonal brace plate  132 . A bushing housing  134  is provided at a distal end of the side walls  126 ,  128  to hold a bushing  136  allowing the axle to pivot about the bushing  136 . 
         [0052]      FIGS. 10 and 10A  illustrate an alternative 16-wheel embodiment of the unitized hydraulic suspension system having two side by side unitized hydraulic suspension systems supporting co-linear sets of axles to effect dual lane loading.  FIG. 10  shows the wheel groups, parts of the mounting beam structures  164 ,  166  for each unitized hydraulic suspension and a slide box assembly  184  along which the mounting beam structures slide to reposition the wheel groups in an extended or a retracted position in relation to one another. In  FIG. 10 , the wheel groups are in a retracted position.  FIG. 10A  includes the turntable  200  that allows the entire 16-wheel assembly to be turned. In  FIG. 10A , the 8-wheel groups are in relative extended position in relation to  FIG. 10 . 
         [0053]      FIG. 9  is intended to show the relative placement of the two unitized suspension systems  150 ,  152  in the 16-wheel dual laning embodiment and accordingly the figure does not show the mounting beam structures  164 ,  166  for each suspension system or the connecting slide box assembly  184  for connecting the two mounting beam structures  164 ,  166 . 
         [0054]    Generally speaking, each of the two unitized suspensions is mounted to a mounting beam structure  164  or  166 . The mounting beam structure  164 ,  166  slide within a slide box assembly  184  allowing for the retraction or extension of the mounting beam structures  164 ,  166  in relation to one another, so as to retract or extend the unitized suspension systems  150 ,  152  in relation to one another for the dual lane loading transition. 
         [0055]      FIG. 11  shows the two side by side unitized hydraulic suspensions mounted on their respective mounting beam structures, but without the slide box assembly, the wheels or the axles for clarity. 
         [0056]    Referring to  FIG. 12 , front and rear cylinders  154 ,  156  are each attached between parallel cylinder lug brackets  158 ,  160  but that have a different shape than the cylinder lug brackets  97 ,  99  shown in the embodiment of  FIG. 3 . In the present embodiment, the lug brackets  158 ,  160  have a U-shape that allows the lug brackets  158 ,  160  to clear the mounting beam structures and the slide box assembly  184  which extend between the upper ends of lug brackets  158 ,  160  as best appreciated by reference to  FIG. 12 . Such arrangement allows the unitized suspension system and the mounting beam structure that it depends from, to slide along the slide box assembly  184  without interference by the lug brackets. 
         [0057]    As in the preferred embodiment, the lug brackets are integrated into the hanger structure  157  which forms a rigid structure providing opposed points of attachment  171 ,  173  to the top ends of the front and rear cylinders  154 ,  156 . 
         [0058]    Referring to  FIGS. 13-16  the mounting beam structures  164 ,  166  are sufficiently elongated to span and properly support their respective unitized suspensions. A base plate  191  serves as an attachment surface to a corresponding support plate  193  of the hanger  157 . The base plate  191  is attached by means of two gussets  195 ,  197  to an elongated base  199  of the mounting beam structure  164 . Opposed side walls  170 ,  172  include angled shoulders  174 ,  176 , each supporting an additional friction plate  178  (the opposing friction plate not being visible in these views). The inboard ends of the mounting beam structures include rollers  180 ,  182  for permitting the mounting beam structures to slide along the slide box assembly  184 . 
         [0059]    A cylinder piston mount  186  is provided at an outboard end of each of the beam structures  164 ,  166 . As will be discussed below the piston of one of two back-to-back telescoping cylinders is secured to the piston mount. 
         [0060]    The mounting beam structures  164 ,  166  are adapted to slide along a connecting slide box assembly  184  which is shown in isolated views in  FIGS. 17 and 18 . The slide box assembly  184  comprises a top wall  186 , two side walls  188 ,  190  and angled corners walls  192 ,  194 , each of which is in a sliding relationship with the corresponding walls of the mounting beam structures  164 ,  166 . Slide box assembly  184  further comprises a center gusset  196  for retaining one end of each of two telescoping cylinders  198 ,  200 . 
         [0061]      FIG. 19  shows the slide box assembly  184 , the two mounting beam structures  164 ,  166  and including two telescoping cylinders  198 ,  200 . In  FIG. 19 , the viewing side of the slide box assembly and of one of the mounting beam structures have been removed. 
         [0062]    When actuated, the telescoping cylinders  198 ,  200  act to retract and extend the mounting beam structures  164 ,  166  along the slide box assembly  184 , thereby retracting or extending the unitized suspension systems that are mounted to the mounting beam structures  164 ,  166  in relation to one another to facilitate dual lane loading. Each of cylinders  198 ,  200  is attached at one end to the central gusset  196  of the slide box assembly and at the other end to the piston mounts  186 . 
         [0063]      FIGS. 20 and 21  show the slide box assembly  184 , the two mounting beam structures  164 ,  166  and a turntable system for enabling the coordinated turning of the  16 -wheel assembly. 
         [0064]    Two roller assemblies  202 ,  204  are mounted to the top of the slide box assembly  184 . The slide box assembly  184  is pivoted about a turntable or steering arm  206  by means of a central bolt (not visible in these views). The turntable is supported from a coupler structure  208  that is mounted to the frame of the vehicle. Cylinder mounts  210  and  212  are provided on the upper surface of the slide box assembly  184  for attaching one end of respective cylinders  214 ,  216  for actuating steering of the  16 -wheel assembly. In doing so, the rollers  202 ,  204  roll against the turntable rolling surfaces to effect steering of the assembly. 
         [0065]    The use of the unitized hydraulic suspensions of the preferred embodiment simplify the successful implementation of a dual laning heavy haul hydraulic suspension trailer by minimizing the number of separate suspensions that need to be extended or retracted in a coordinated manner or that need to be steered in a coordinated manner. Rather than needing to extend or retract four independently suspended axles, only two unitized independent suspensions need to translated in relation to one another. 
         [0066]    In the foregoing specification, the invention has been described with reference to specific embodiments thereof. However, the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.