Frame for heavy-duty vehicles

A frame for a heavy-duty vehicle includes a pair of spaced-apart and longitudinally-extending main members. At least two cross members extend between and are attached to the main members. Each one of at least a pair of hangers is attached to and depends from a respective one of the main members for suspending an axle/suspension system from the frame. A force distribution assembly is attached to the main members and the hangers and includes a component that deforms or shears in an extreme event. The force distribution assembly extends perpendicularly between the main members and interrupts the transmission of forces encountered by the axle/suspension system that move through each one of the hangers to its respective main member, and redirects at least a portion of such forces across said force distribution assembly and into the other one of the main members.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to heavy-duty vehicles, and in particular, to frames and subframes for heavy-duty vehicles. More particularly, the present invention is directed to frames and subframes for heavy-duty vehicles which include selected components that are bolted together in a manner that provides efficient distribution of forces, and include components for absorbing energy in an extreme event during vehicle operation.

2. Background Art

Heavy-duty vehicles that transport cargo, for example, tractor-trailers or semi-trailers, and straight trucks such as dump trucks, typically include leading or trailing arm suspension assemblies that connect the axles of the vehicle to the frame of the vehicle. In some heavy-duty vehicles, the suspension assemblies are connected directly to the primary frame of the vehicle. In other heavy-duty vehicles, the primary frame of the vehicle supports a subframe, and the suspension assemblies connect directly to the subframe. For those heavy-duty vehicles that support a subframe, the subframe can be non-movable or movable, the latter being commonly referred to as a slider box, slider subframe, slider undercarriage, or secondary slider frame. For the purpose of convenience and clarity, reference herein will be made to a slider box, with the understanding that such reference is by way of example, and that the present invention applies to heavy-duty vehicle primary frames, movable subframes and non-movable subframes.

In the heavy-duty vehicle art, one or more axle/suspension systems usually are suspended from a single slider box. It is understood that a slider box outfitted with usually two axle/suspension systems typically is referred to as a slider or slider tandem, and for purposes of convenience and clarity, will hereinafter be referred to as a slider tandem. Of course, a slider box may also be outfitted with a single axle/suspension system, or three or more axle/suspension systems. By way of example, reference herein shall be made to a slider tandem having a pair of axle/suspension systems mounted thereon, with the understanding that such reference also applies to a slider outfitted with one, three or more axle/suspension systems. The slider tandem in turn is mounted on the underside of the trailer primary frame, and is movable longitudinally therealong to provide a means for variable load distribution and vehicular maneuverability.

More specifically, the amount of cargo that a trailer may carry is governed by local, state and/or national road and bridge laws, and is dependent on proper load distribution. The basic principle behind most road and bridge laws is to limit the maximum load that a vehicle may carry, as well as limit the maximum load that can be supported by individual axles. A trailer having a slider tandem gains an advantage with respect to laws governing maximum axle loads. More particularly, proper placement of the slider tandem varies individual axle loads or redistributes the trailer load so that it is within legal limits

A slider box typically includes a pair of longitudinally extending elongated main members or rails that are parallel to one another. The parallel spacing between the main members is maintained by cross members, which extend transversely between and are connected to the main members The main members and the cross members of prior art slider boxes are usually made of steel, which enables the cross members to be butted against and welded to the inboard surface of the main members. Other components that are part of or are related to the slider box, such as reinforcing members and suspension assembly hangers, typically are also made from steel and are welded to the main members and/or the cross members. The slider box typically is movably attached to the vehicle primary frame by a retractable pin mechanism.

One consideration in the design of any slider box is weight. More particularly, for at least two reasons it is desirable to reduce the weight of a slider box as much as possible, while still maintaining performance characteristics and robustness. First, such a weight reduction decreases the amount of fuel that the heavy-duty vehicle consumes, leading to a corresponding reduction in fuel costs. Second, local, state and/or national road and bridge laws typically set a maximum weight limit for a trailer load, which includes the weight of the trailer and the payload carried on or in the trailer. If the weight of the slider box is reduced, more vehicle weight capacity can be devoted to the payload, enabling a larger payload to be transported and increasing the overall profitability of the vehicle.

To reduce the weight of the slider box, the use of structural materials that are lighter than steel, such as aluminum and aluminum alloys for the main members, cross members, and other components has often been explored in the prior art. However, certain characteristics of aluminum, such as high thermal conductivity and a low melting point, make the welding of aluminum components different, and potentially more difficult, than the welding of steel components. In addition, aluminum components that are welded together may exhibit fatigue at the weld area, thereby potentially creating a weaker connection when compared to steel components that are welded together.

The potential for a weaker connection may become a concern at the interface between the main members and the hangers, and potentially at any interface between the cross members and the hangers. Since the axle/suspension system typically pivotally connects to the hangers, which are welded to the main members, the interface between the hangers and the main members is instrumental in reacting the vertical, fore-aft, side and torsional loads encountered by the axle/suspension system. More particularly, loads or forces acting on the axle/suspension system, such as brake loads, fore-aft loads, side loads, curbing loads, vertical loads and torsional loads, tend to cause the hanger to rock or move fore-to-aft and side-to-side. Such movement of the hanger highly stresses the rigid attachment of the hanger to the main member and potentially any rigid attachment of the hanger to the cross member, which may cause a potentially less-than-optimal weld to fail. Thus, the use of aluminum components, which may not facilitate a welded connection that is as strong as a weld between steel components, may undesirably fail.

To overcome the concern of a potential failure of a welded connection between aluminum components, the components may instead be bolted together. The use of a bolted connection provides strength, enables compliance, and reduces stress risers. However, in the prior art, it has been difficult to attach the hanger to the main member and/or cross member using bolts in a manner which enables adequate distribution among the bolts of the different loading forces that act on the axle/suspension system and thereby achieve a satisfactory fatigue life of the slider box components

Moreover, another consideration in the design of any slider box is the ability of the slider box to withstand extreme events. That is, the slider box and the axle/suspension system of a heavy-duty vehicle must also be durable enough to withstand the force created by events such as single-wheel impacts caused by a wheel striking a bump in a road, a large pot-hole, or highway guard rails. Such extreme events also include the static hang-up of a wheel in service, which is a low-speed event in which a tire is hung up or stopped temporarily during service until the vehicle pulls through the event. When a vehicle encounters an extreme event, a vertical crush force is produced which potentially can cause significant damage to the slider box. More specifically, in a typical prior art slider tandem, when a vertical crush force is produced, a force in the aft direction is produced wherein the beam of a trailing beam suspension pulls toward the rear of the vehicle, in turn causing the rear portion of the hanger to which it is pivotally attached to impact or move vertically upward into the main member and/or cross member with significant force.

This vertical crush force may be of differing magnitudes at different points throughout the suspension system, depending on the nature of the impact. For example, a static hang-up of a wheel in service is likely to produce a greater force than simply striking a bump in the road. A side force may also be produced if the impact is on a single wheel, which would cause the beam to pull back and sideways, causing the hanger to twist. These impacts could damage, or in an extreme case, cause a slider box main member and/or one or more of the attached cross members to fail, in either instance eventually requiring replacement, which is costly and time-consuming. Although the hanger typically is not damaged from such impacts, it usually also is replaced along with the main member and/or cross member. This design of a typical slider tandem causes many heavy-duty vehicles containing such slider tandems to be out of service for extended periods of time after such extreme events until the entire slider box can be replaced.

These potential concerns have created a need in the art for lighter weight heavy-duty vehicle primary frames and subframes that include selected components which are joined in a stronger and more dependable manner than by welding nonferrous materials, which are capable of efficient distribution of forces, and which reduce potential damage from extreme events.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide heavy-duty vehicle primary frames and subframes that are lighter in weight than prior art subframes having steel components, with connections between selected components that are stronger than connections established by welding the components.

Another objective of the present invention is to provide heavy-duty vehicle primary frames and subframes that efficiently distribute loading forces.

Yet another objective of the present invention is to provide heavy-duty vehicle primary frames and subframes that reduce potential damage from extreme events

These objectives and advantages are obtained by the frame for heavy-duty vehicles of the present invention. In an exemplary embodiment of the invention, the frame includes a pair of spaced-apart, parallel, elongated and longitudinally extending main members At least two cross members extend between and are attached to the main members Each one of at least a pail of hangers is attached to a respective one of the main members for suspending an axle/suspension system from the frame. A force distribution assembly is attached to the main members and to the hangers. The force distribution assembly extends perpendicularly between the main members and interrupts the transmission of forces encountered by the axle/suspension system that move through each one of the hangers and into its respective main member, and redirects at least a portion of the forces across the force distribution assembly and into the other one of the main members

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As mentioned above, for the purposes of clarity and convenience, reference herein is made to a slider box, with the understanding that such reference is by way of example, and the present invention applies to heavy-duty vehicle primary frames, movable subframes and non-movable subframes. In order to better understand the slider box of the present invention, a prior art slider box for a tractor-trailer is shown inFIG. 1, is indicated generally at120, and now will be described. Slider box120includes a pair of main members121and front and rear generally K-shaped cross member structures122A and122B, respectively. Front and rear pairs of hangers123A and123B, respectively, are attached to respective ones of main members121for suspending axle/suspension systems. A retractable pin mechanism124is incorporated into slider box120for selective positioning of the slider box beneath the vehicle primary frame, as will be described in greater detail below. Reference to slider box120includes styles of slider boxes known in the art other than K-frame type slider boxes, such as perpendicular-frame or ladder-type slider boxes, and slider boxes suspending other types of suspension assemblies than those described and shown herein, such as spring suspensions. For the sake of clarity and consistency, reference hereinbelow will be made to slider box120with the understanding that such reference generally includes all types of slider boxes known to those skilled in the art.

With continuing reference toFIG. 1, each main member121is a longitudinally-extending, elongated, generally C-shaped beam made of steel. The open portion of each main member121is opposed to the open portion of the other main member and faces inboard relative to slider box120. Main members121are connected to each other in a spaced-apart parallel relationship by K-shaped cross member structures122A, B.

Each K-shaped cross member structure122includes a base member160which extends between and is perpendicular to main members121. Each base member160is a generally C-shaped beam made of steel. The open portion of each base member160faces in a frontward direction. Each end of base member160nests in and abuts the inboard open portion of a respective one of main members121, and is secured therein by welding. Each front hanger123A abuts and is attached by welding to the lowermost surface of a respective one of main members121at a location directly beneath base member160of front K-shaped cross member structure122A. Each rear hanger123B similarly is attached at a location directly beneath base member160of rear K-shaped cross member structure122B

Each K-shaped cross member structure122further includes a pair of inclined, diagonal or angled members161, each of which is a generally C-shaped beam also made of steel. The open portion of each angled member161faces in an outboard-frontward direction, and each of the angled members extends between generally the middle portion of base member160and a respective one of main members121. The front end of each angled member161abuts and is attached to the rearwardmost surface of base member160at an angle by welding, and the rear end of each of the angled members is nested in and abuts at an angle the open portion of a respective one of main members121, and also is attached thereto by welding Thus, it can be seen that base member160and angled members161form an integral K-shaped cross member structure122which interconnects and maintains main members121in a spaced-apart parallel relationship.

A reinforcing cross member170is disposed frontwardly of retractable pin mechanism124, and extends between and is perpendicular to main members121Reinforcing cross member170is a generally C-shaped beam made of steel, the open portion of which faces in a rearward direction. Each end of reinforcing member170nests in and abuts the open portion of a respective one of main members121, and is secured therein by welding. An optional reinforcement bar171, which extends between the rearwardmost ends of main members121, adds additional strength to the structure, and is attached thereto by welding.

One or more openings129are formed in the vertically extending surface of front reinforcing cross member170, each base member160and each angled member161, and each of the openings129is aligned with the corresponding openings formed in the other members to provide for passage of air and/or fluid conduits, electrical lines, and the like used in the operation of the tractor-trailer (not shown).

Each main member121has a pair of rail guides125mounted on its outboard surface by bolts126. Each rail guide125is mounted adjacent to a respective one of the ends of main member121. A low friction strip127is attached to the uppermost surface of each main member121by recessed fasteners128, and extends generally the entire length of main member121Strip127is formed of any suitable low friction material, such as ultra-high molecular weight polyethylene

As mentioned hereinabove, and as best shown inFIG. 2, prior art slider box120supports front and rear axle/suspension systems, forming a slider tandem136However, only front axle/suspension system130is shown in the drawings and described herein since the front and rear systems are identical in structure and operation. Moreover, inasmuch as axle/suspension system130is suspended from slider box120, but does not form an integral part thereof, only the major components of the system will be cited for aiding in the description of the environment in which the prior art slider box operates.

Axle/suspension system130includes generally identical suspension assemblies131suspended from each hanger123A of the pair of front hangers. Each suspension assembly131includes a suspension beam132which is pivotally mounted on hanger123A in a usual manner. An air spring133is suitably mounted on and extends between the upper surface of the rearwardmost end of suspension beam132and main member121at a location directly beneath the outboard end of a respective one of angled members161of K-shaped cross member structure122A. A shock absorber134extends between and is mounted on suspension beam132and the respective angled member161. Another component of suspension assembly131, mentioned herein only for the sake of relative completeness, is an air brake135. An axle137extends between and is captured in the pair of suspension beams132of axle/suspension system130. One or more wheels138are mounted on each end of axle137. A reinforcement member172(FIG. 1) is mounted by any suitable means in the open portion of each main member121frontwardly of and adjacent to each end of rearward base member160and directly above rearward hanger123B, to provide additional strength to slider box120for supporting the rearward hanger and its associated suspension assembly.

Slider tandem136is movably mounted on trailer body140(FIG. 3) by slidable engagement of rail guides125with elongated, longitudinally-extending, spaced-apart, parallel, and generally Z-shaped rails141, which are mounted on and depend from the underside of the trailer body. Each low friction strip127abuts the bottom surface of the uppermost portion of a respective one of rails141to provide a smooth, generally friction-free contact surface for slidable movement of slider tandem136on trailer body140.

Slider tandem136can be selectively positioned relative to trailer body140for optimum load distribution by retractable pin mechanism124. As best shown inFIGS. 1 and 3, pin mechanism124includes a generally L-shaped handle142which passes through an opening139formed in a selected one of main members121, but usually on the driver's side of the tractor-trailer. It can be seen that the bent end portion of handle142, which extends outwardly from the outboard side of main member121, is accessible for easy grasping by an operator of the tractor-trailer. The inboard end of handle142is pivotally attached to a lever143, which in turn is pivotally attached to a pair of arms144which extend in opposite outboard directions from lever143. Level143further is attached to an elongated pivot rod145which passes rearwardly through an opening (not shown) formed in base member160of front K-shaped cross member structure122A. The end of pivot rod145remote from lever143similarly is attached to a remote lever147, which in turn is pivotally attached to a pair of arms148which extend in opposite outboard directions from lever147. The outboard end of each of arms144,148is bent and is pivotally attached to the inboard end of a pin149.

With reference now toFIGS. 1 and 2, the inboard end of each pin149is slidably mounted in an opening (not shown) formed in a bracket151which is attached by suitable means such as welding to a respective one of base members160. The enlarged outboard end of each pin149passes through a generally round or circular-shaped opening152formed in a respective one of main members121. When it is desired to lock slider tandem136in a selected position relative to trailer body140(FIG. 3), the slider box main member openings152are aligned with selected ones of a plurality of correspondingly-sized and shaped openings153formed in rails141of the trailer body (FIG. 2). Each pin149automatically extends through the selected aligned openings152,153since the pin is biased in an outboard direction by a coil spring154captured between bracket151and the enlarged outboard end of pin149. When it is again desired by the operator of the tractor-trailer to move slider tandem136beneath trailer body140, the parking brake of the trailer is engaged, handle142is pulled in an outboard direction and against the bias of coil springs154to retract pins149out of trailer rail openings153, and slider tandem136is moved longitudinally along trailer rails141until slider box main member openings152align with selected trailer rail openings153and pins149engage therewith as described hereinabove for maximizing load distribution.

Although the described prior art steel slider box120satisfactorily performs its intended function, in an attempt to desirably reduce the weight of slider box120, the use of structural materials that are lighter than steel for components such as main members121, cross member structures122, hangers123and reinforcing cross member170has been explored. Such materials include aluminum and aluminum alloys, as well as other non-ferrous metals and alloys, and composite materials.

However, characteristics of these materials make the typical prior art joining of components via welding, such as described above, undesirable. For example, the high thermal conductivity and low melting point associated with aluminum and aluminum alloys make the welding of aluminum components different, and potentially more difficult, than the welding of components made from steel. In addition, components made from aluminum or aluminum alloys that are welded together may exhibit fatigue at the weld area, thereby potentially creating a weaker connection when compared to components made from steel that are welded together, which is of particular concern at the highly-stressed connection between hangers123and main members121. Moreover, prior art slider box120may be susceptible to damage from forces created by extreme events, such as single-wheel impacts and static hang-up of a wheel in service.

Such potential concerns with the prior art process of welding, as applied to generally lighter weight non-ferrous metals and other materials, have created a need in the art for heavy-duty vehicle primary frames and subframes that include selected components which are joined in a stronger and more dependable manner than by welding, that provide efficient distribution of forces, and that reduce potential damage from extreme events. The present invention provides such heavy-duty vehicle primary frames and subframes.

Turning now to the drawings of the present invention, wherein the illustrations are for showing preferred embodiments of the invention, and not for limiting the same,FIG. 4shows a slider tandem218including a first embodiment slider box of the present invention, indicated generally at220. First embodiment slider box220includes a pair of longitudinally extending, spaced-apart parallel main members221, and transversely extending, spaced-apart parallel front and rear cross member sets222A and222B, which extend between and interconnect the main members. First embodiment slider box220includes a front force distribution assembly258A generally disposed under main members221and over front hangers223A, and which preferably extends transversely to the outboard edges of the main members, as will be described in greater detail below A rear force distribution assembly258B similarly is generally disposed under main members221and over rear hangers223B, and preferably extends transversely to the outboard edges of the main members.

Slider box220accommodates a retractable pin mechanism224, which preferably is a pneumatically actuated mechanism including an air bladder225and retractable pins226, as more fully described in U.S. Pat. No. 6,279,933, issued on Aug. 28, 2001 and owned by the same assignee as the present invention, Hendrickson USA, L.L.C. Alternatively, pin mechanism224may be any mechanically or pneumatically actuated mechanism known to those skilled in the art, including a mechanism similar to that as described above for prior art slider box120. An air tank229optionally extends between slider box main members221for convenient storage of compressed air.

A low friction strip227, which is formed of any suitable low friction material, such as ultra-high molecular weight polyethylene, is attached to the uppermost surface of each main member221and extends generally the entire length of the main member. More particularly, main member221preferably is formed with a channel228(FIG. 11) to retain low friction strip227. In the prior art, as shown inFIG. 1, low friction strip127is bolted to a main member121via bolts or fasteners128. Since low friction strip127typically is made of a polymer, its rate of thermal expansion is different from that of a metal main member121. Over time, low friction strip127may bulge between bolts128, which may cause portions of the strip to break off, creating an unsupported area for the movement of slider box120. Having such an unsupported area may contribute to cracking of certain components of slider box120. In addition, the use of bolts128to secure strip127may result in a less-than-flush installation of some bolts, or a backing out of the bolts, which may undesirably cause slider box120to jam. In contrast, low friction strip227interlocks with channel228to secure the strip without the use of bolts128, or reduces the number of bolts, which allows the strip to thermally expand at a different rate from that of main member221without bulging or breaking. In this manner, channel228reduces or eliminates the problems of the prior art, and also reduces or eliminates the cost and weight of the bolts.

With additional reference toFIGS. 5 and 6, first embodiment slider box220supports front and rear axle/suspension systems230A,B, forming slider tandem218Inasmuch as axle/suspension systems230A,B are suspended from slider box220, but do not form an integral part thereof, only the major components of the system will be cited for aiding in the description of the environment in which the slider box operates. Each axle/suspension system230A,B includes a suspension beam231which is pivotally mounted on each respective hanger223A,B in a usual manner via a bushing assembly232. An air spring233is suitably mounted on and extends between the upper surface of the rearwardmost end of suspension beam231and main member221at a location directly beneath a rear cross member251of each cross member set222A,B. A shock absorber234extends between and is mounted on suspension beam231and force distribution assembly258A,B, as will be described in greater detail below. Components of brake system235are shown for the sake of relative completeness, and an axle237extends between and is captured in the pair of suspension beams231.

As best shown inFIGS. 5,7and11, each slider box main member221includes an upper flange241, a lower flange242, and a vertical wall240extending between the upper and lower flanges. Upper flange241preferably extends only inboardly relative to vertical wall240, thereby providing robustness for main members221and an area on which components may be mounted, while also enabling smooth interaction of the outboard surface of the main member with trailer body rails141of the type shown inFIG. 2. Lower flange242preferably extends inboardly and outboardly relative to vertical wall240, thereby providing additional robustness for main members221, and a significant surface area for mounting components, as will be described below. Flanges241,242and vertical wall240each are formed with bolt holes243to receive fasteners, as will also be described in greater detail below

Extending between and interconnecting main members221are front and rear cross member sets222A,B. Turning now toFIGS. 7 and 8and referring to front cross member set222A by way of example, each cross member set includes a front cross member245, an intermediate cross member248and rear cross member251.

Front cross member245includes an upper flange246, a lower flange247, and a vertical wall236extending between the upper and lower flanges. Upper flange246preferably extends rearwardly relative to vertical wall236, while lower flange247preferably extends frontwardly relative to the vertical wall, thereby enabling convenient connection with main members221and force distribution assembly258, as will be described below. Flanges246,247each are formed with bolt holes243to receive fasteners. Vertical wall236is formed with openings244to reduce weight and to provide for passage of air and/or fluid conduits, electrical lines, and the like used in the operation of the tractor-trailer (not shown).

Intermediate cross member248includes an upper flange249, a lower flange250, and a vertical wall238extending between the upper and lower flanges. Upper flange249preferably extends frontwardly relative to vertical wall238, while lower flange250preferably extends rearwardly relative to the vertical wall, thereby enabling convenient connection with main members221and force distribution assembly258, as will be described below. Flanges249,250each are formed with bolt holes243to receive fasteners. Vertical wall238is formed with openings244to reduce weight and to provide for passage of air and/or fluid conduits, electrical lines, and the like used in the operation of the tractor-trailer (not shown).

Each end of front and intermediate cross members245,248preferably is connected to main members221by mechanical fasteners, such as bolts. More particularly, a selected one of bolt holes243formed in the driver's side of front cross member upper flange246aligns with a respective one of the bolt holes formed in driver's side main member upper flange241, and a selected one of the bolt holes formed in the passenger side of the front cross member upper flange aligns with a respective one of the bolt holes formed in the passenger side main member upper flange, thereby enabling a bolt (not shown) to secure each end of front cross member245to its respective main member221. Likewise, selected ones of bolt holes243formed in front cross member lower flange247align with respective selected bolt holes formed in the inboard-facing portion of main member lower flange242, enabling a bolt to secure cross member245to each respective main member221. Preferably, front cross member245is received between main member upper and lower flanges241,242, thereby enabling the main member to capture and secure a respective end of the front cross member. Intermediate cross member248is connected to each main member221in the same manner as front cross member245, and is positioned rearwardly of and spaced from the front cross member along the main members. Front and intermediate cross members245,248are vertically aligned with force distribution assembly258for efficient distribution of forces, as will be described in greater detail below.

Cross member set222A also includes a rear cross member251to provide additional robustness for slider box220. Rear cross member251includes an upper flange252, a lower flange253, and a vertical wall239extending between the upper and lower flanges Upper and lower flanges252,253preferably extend frontwardly relative to vertical wall239and are formed with bolt holes243to receive fasteners. Vertical wall239is formed with bolt holes243to receive fasteners, and with openings244to reduce weight and to provide for passage of air and/or fluid conduits, electrical lines, and the like used in the operation of the tractor-trailer (not shown). With reference toFIG. 9, to enable attachment of rear cross member251to main member221, the cross member connects to an adapter bracket254, preferably via mechanical fasteners such as horizontally-disposed bolts283. Adapter bracket254preferably is received between and bolted to main member upper and lower flanges241,242, thereby enabling the main member to capture and secure the adapter bracket, and in turn, rear cross member251. To provide a mounting area for the top of air spring233, and to provide reinforcement of rear cross member251and a secure fit for adapter bracket254, an optional reinforcing plate255may be added between the adapter bracket and main member lower flange242.

With reference toFIG. 6, slider box220optionally includes a reinforcement member256, which extends between the rearwardmost ends of main members221to add additional strength and robustness to the structure. Reinforcement member256preferably is mechanically fastened to an adapter bracket257, which in turn is received between and bolted to main member upper and lower flanges241,242.

As best shown inFIGS. 7 and 8and referring to front hangers223A by way of example, the hangers are attached to main members221and front and intermediate cross members245,248by force distribution assembly258, which will be described in greater detail below Each hanger223A includes a flanged outboard member259and a flanged inboard member260. Outboard member259includes front flanges263, a rear flange264, and a ribbed longitudinal wall261extending between the front and rear flanges. Longitudinal wall261has an opening262formed therein for receiving bushing assembly232(FIG. 5). Front flanges263extend inboardly and outboardly relative to longitudinal wall261, and rear flange264extends only outboardly relative to the longitudinal wall. Inboard member260includes a front flange266, a rear flange267, and a generally longitudinal wall265extending between the front and rear flanges. Longitudinal wall265also includes opening262formed therein for receiving bushing assembly232. Front and rear flanges266,267both extend inboardly relative to longitudinal wall265.

With additional reference toFIG. 11, outboard and inboard hanger members259,260, respectively, are assembled with the inboard-facing surface of outboard member front flange263in abutment with the outboard-facing surface of inboard member front flange266, and the front flanges then are secured together via a vertical weld268. Weld268is sufficient to join hanger outboard and inboard members259,260, since it experiences reduced in-service loading due to the efficient force distribution provided by force distribution assembly258A, as will be described below. Optionally, rather than abutting and being welded together, front flange263of outboard hanger member259and front flange266of inboard hanger member260may form an overlap joint, which is secured by mechanical fasteners. When outboard and inboard hanger members259,260are secured together, a channel269(FIG. 8) is formed for the receipt of beam231(FIG. 5) in hanger223A, and the beam is pivotally secured to the hanger via bushing assembly232in a manner well-known in the art.

Turning now toFIG. 10, force distribution assembly258A includes a pair of fore-aft spaced apart parallel, laterally-extending lower cross members270. Lower cross members270preferably include a generally inverted L-shaped cross section and, as shown inFIGS. 5,7and8, are disposed under slider box main members221and over hangers223A, and preferably extend to the outboard edges of the slider box main members. More particularly, each lower cross member270includes an upper flange271which is disposed above hangers223A and is formed with bolt holes272for mechanical attachment to the lower surface of main member lower flange242via vertically-disposed bolts284(FIG. 7). Each lower cross member270also is bolted via horizontally-disposed bolts283to an upper portion of respective ones of flanges263,266and264,267of hangers223A In this manner, each lower cross member270, by being disposed below main members221and generally above hangers223A and extending transversely to the outboard edges of the main members, thereby interconnects the driver's side and passenger side hangers and main members. An optional front reinforcing member273, which preferably includes an inverted L-shaped cross section, nests in front of and is secured to each end of front lower cross member270An optional rear reinforcing member274, which also preferably includes an inverted L-shaped cross section, nests behind and is secured to each end of rear lower cross member270Front and rear reinforcing members273,274provide additional robustness for force distribution assembly258A and the rear reinforcing member preferably is formed with mounting projections275(FIG. 8) to enable the connection of shock absorbers234.

Maintaining the parallel relationship between lower cross members270, thereby forming a box-type structure, is a bottom plate277of an energy-absorbing component276. More particularly, bottom plate277of energy-absorbing component276is disposed on the top surface of and is welded to outboard and inboard hanger members259,260. The forward-facing edge of plate277abuts the rearward-facing surface of front lower cross member270, and the rearward-facing edge of the plate abuts the forward-facing surface of the rear lower cross member. The outboard edge of plate277vertically aligns with the outboard edges of hanger outboard flange member259, and with the outboard edge of each lower cross member270. In this manner, each bottom plate277cooperates with lower cross members270to form a rectangular structure about hangers223A for the distribution of forces, as will be described below.

Energy-absorbing component276(FIG. 10) is a sacrificial component that deforms in an extreme event, as will also be described below. Energy-absorbing component276includes a top plate278that extends generally parallel to bottom plate277. The upper surface of top plate278generally aligns with the upper surface of cross member upper flange271, and includes bolt holes279for mechanical attachment to main members221via vertically-disposed bolts284(FIG. 7) Extending between bottom and top plates278,279is a vertical web280, which includes openings281and a rib282formed between the openings. As will be described in greater detail below, rib282deforms in an extreme event to reduce or eliminate damage to main members221, cross member sets222A,B, and other components.

With reference toFIG. 11, horizontally-disposed bolts283preferably are used to attach lower cross members270to hangers223A,B and vertically-disposed bolts preferably are used to attach the lower cross members to main member lower flange242. Front lower cross member270is aligned with and mechanically fastened to lower flange247of front cross member245(FIG. 5) with vertically-disposed bolts284, while the rear lower cross member is aligned with and mechanically fastened to lower flange250of intermediate cross member248(FIG. 8), also with vertically-disposed bolts. A spacer plate285(FIG. 11) is disposed between lower cross members270and each respective front and intermediate cross member245,248to maintain uniform spacing. Of course, horizontally-disposed and vertically-disposed bolts283,284preferably are secured with nuts286, as known in the art.

To provide additional reinforcement to main members221, angle braces287optionally are bolted to and extend between the outboard portion of lower flange242and vertical wall240(FIG. 7). As shown inFIGS. 5 and 6, each main member221has a pair of rail guides288mounted on its outboard surface adjacent to a respective one of the ends of the main member. Additional components, such as a mechanical stop assembly290(FIG. 6) to reduce or prevent dock walk, as known in the art, may optionally be connected to main members221and/or other components of slider box220.

First embodiment slider box220of the present invention provides a robust structure that is interconnected by mechanical fasteners, thereby reducing the potential for failure of welds in high-stress areas. Moreover, the use of force distribution assembly258A,B under main members221enables forces encountered by axle/suspension system230A,B to generally travel up each respective hanger223A,B and across lower cross members270, for distribution across to the opposing main member. In this manner, forces encountered by the system are distributed among main members221, rather than being isolated in a single interface between a hanger and respective main member, as in many prior art systems.

More particularly, since lower cross members270are disposed below main members221and generally above hangers223A,B, a reduction in the moment arm along which loading forces occur is achieved, thus reducing the forces that reach the main member above the respective hanger that is under load This reduction of the moment arm is due to lower cross members270channeling side loads laterally and vertically into a respective main member221that is opposite the load input. That is, in the prior art, loads are transmitted from the bushing assembly up through the continuous structure of a hanger that is welded to a respective main member. In contrast, lower cross members270interrupt the prior-art continuous structure and thereby interrupt the continuity of the load being transmitted up each hanger223A,B to each respective main member221, thereby reducing the moment arm along which the forces act, which in turn reduces the magnitude of the resultant forces. Since they are linked together, lower cross members270work to unify the fore-aft forces experienced by outboard hanger wall261and inboard hanger wall265, and the side load forces experienced by hanger front flanges263,266and rear flanges264,267. It should be noted that the reduction of the moment arm is desirably achieved without any change in height of the system. That is, the distance from bushing assembly232to each respective main member221remains the same, but the intervening structure of lower cross members270changes the load path and reroutes forces, thereby reducing the moment arm and distributing the loads up into the main members and cross member sets222A,B to react the loads in an effective manner.

Through the use of force distribution assembly258A,B, side loads and fore-aft loads are reacted by horizontally-disposed and vertically-disposed bolts283,284, while lesser shear forces are reacted by the welds between hangers223A,B and bottom plate277, which are sufficient for the task.

First embodiment slider box220of the present invention also provides a structure that reduces potential damage from extreme events First, lower cross members270of force distribution assembly258A,B are designed to bend, but not break, in an extreme event such as a wheel impacting a guardrail post. The design of slider box220isolates any potential damage to an easily-repairable component, rather than other components such as main members221or cross member sets222A,B. In order to prevent continued operation in a damaged state, thereby preventing further damage, lower cross members270optionally bend enough in an extreme event to move axle237into a noticeable misalignment, which alerts the vehicle operator that repairs must be made, while maintaining enough strength to keep the axle attached to slider box220.

In addition, first embodiment slider box220includes the use of energy-absorbing component276to reduce potential damage from extreme events. Energy-absorbing component276includes rib282, which absorbs the force of the impact from an extreme event and is designed to fail when it teaches its vertical force limit. By being mounted between each hanger223A,B and its respective main member221, energy-absorbing component276deflects the force under heavy fore-aft loads, side loads and/or vertical loads to protect main members221, cross member sets222A,B and other structural components from the stress caused by the force of the impact. After absorbing an impact, energy-absorbing component276can be replaced in a much more efficient and inexpensive manner than replacing main members221and cross member sets222A,B. In most cases, little to no damage occurs to main members221or cross member sets222A,B, since energy-absorbent component276absorbs the energy from the extreme impact and maintains the integrity of the main members and cross member sets.

In this manner, first embodiment slider box220provides a lighter weight heavy-duty vehicle subframe that includes components which are joined in a stronger and more dependable manner than by welding, efficiently distributes forces, and reduces potential damage from extreme events. It should be noted that most components of slider box220, including main members221, front cross members245, intermediate cross members248, rear cross members251, reinforcing member256, adapters254and257, outboard hanger member259, inboard hanger member260, lower cross members270and energy-absorbing component276, preferably are made from a light-weight material, such as aluminum or an aluminum alloy, and include a uniform cross section that enables the components to be extruded or pultruded and then saw cut. Extruding, or pultruding, and saw-cutting aluminum components enables first embodiment slider box220to be lighter in weight than prior art slider boxes and relatively economical to manufacture.

Turning now toFIGS. 12-13, a second embodiment slider box of the present invention is shown and is indicated generally at320. Second embodiment slider box320includes a pair of longitudinally extending, spaced-apart parallel main members321, and transversely extending, parallel spaced front and rear cross member pairs322A and322B, which extend between and interconnect the main members. Second embodiment slider box320includes a front lower cross member or force distribution assembly354A generally disposed under main members321and over front hangers323A, and which preferably extends transversely to the outboard edges of the main members, as will be described in greater detail below. A rear lower cross member or force distribution assembly354B is disposed under main members321and over rear hangers323B, and preferably extends transversely to the outboard edges of the main members. As will be described below, main members321have a generally rectangular cross section, which increases the strength of the main members and their ability to distribute loading forces, thereby in turn increasing the strength of second embodiment slider box320over other slider box designs.

Second embodiment slider box320accommodates a retractable pin mechanism324, of which pins326are shown for the purpose of illustration. Pin mechanism324may be any mechanically or pneumatically actuated mechanism known to those skilled in the art, including a mechanism similar to that as described above for prior art slider box120or first embodiment slider box220. A low friction strip327, which is formed of any suitable low function material, such as ultra-high molecular weight polyethylene, is attached to the uppermost surface of each main member321and extends generally the entire length of the main member. More particularly, a channel (not shown) preferably is formed in main members321and low friction strip327interlocks with the channel without the use of bolts or fasteners, or with a reduced number of bolts or fasteners, in a manner similar to that as described above for channel228and low friction strip227of first embodiment slider box220(FIG. 11).

Each main member321is a longitudinally-extending, elongated integrally-formed beam having a generally rectangular-shaped cross section preferably being made of a metal such as aluminum or an aluminum alloy. Main members321each include a pair of spaced-apart parallel inboard and outboard vertical sidewalls330and331, respectively. With additional reference toFIG. 14, main members321each also include an upper horizontal wall332with an inboardly-extending flange333, which provides robustness for the main members and an area on which components may be mounted, while also enabling smooth interaction of the outboard surface of the main member with trailer body rails141of the type shown inFIG. 2. Main members321each also include a lower horizontal wall334with an inboardly-extending flange335and an outboardly-extending flange336, thereby providing additional robustness for the main members, and a significant surface area for mounting components. Flanges333,335,336each are formed with bolt holes337to receive fasteners, as will be described below.

Extending between and interconnecting main members321are front and rear cross member pairs322A,B. Referring to front cross member pair322A by way of example, each cross member pair includes a front cross member338and a rear cross member363. Front cross member338includes an upper flange340, a lower flange341, and a vertical wall339extending between the upper and lower flanges. Upper and lower flanges340,341preferably extend frontwardly relative to vertical wall339, thereby enabling convenient connection with main members321and lower cross member354A, as will be described below. Flanges340,341each are formed with bolt holes343to receive fasteners344. Vertical wall339is formed with openings342to reduce weight and to provide for passage of air and/or fluid conduits, electrical lines, and the like used in the operation of the tractor-trailer (not shown).

Rear cross member363includes an upper flange365, a lower flange366, and a vertical wall364extending between the upper and lower flanges. Upper and lower flanges365,366preferably extend rearwardly relative to vertical wall364, thereby enabling convenient connection with main members321and lower cross member354A, as will be described below. Flanges365,366each are formed with bolt holes343to receive fasteners344. Vertical wall364is formed with openings342to reduce weight and to provide for passage of air and/or fluid conduits, electrical lines, and the like used in the operation of the tractor-trailer (not shown)

Each end of front and rear cross members338,363preferably is connected to main members321by mechanical fasteners, such as bolts or rivets344. More particularly, a selected one of bolt holes343formed in the driver's side of front cross member upper flange340aligns with a respective one of bolt holes337formed in driver's side main member upper inboard flange335, and a selected one of the bolt holes formed in the passenger side of the front cross member upper flange aligns with a respective one of the bolt holes formed in the passenger side main member upper inboard flange, thereby enabling bolt344to secure each end of front cross member338to its respective main member321. Likewise, selected ones of bolt holes343formed in front cross member lower flange341align with respective selected bolt holes337formed in main member inboard lower flange335, enabling bolt344to secure cross member338to each respective main member321Preferably, front cross member338is received between main member inboard upper and lower flanges333,335, thereby enabling the main member to capture and secure a respective end of the front cross member Rear cross member363is connected to each main member321in the same manner as front cross member338, and is positioned rearwardly of and spaced apart from the front cross member along the main members. Front and rear cross members338,363are vertically aligned with lower cross member354A for efficient distribution of forces, as will be described in greater detail below.

Referring to front hangers323A by way of example, the hangers are attached to main members321and front and rear cross members338,363by lower cross member or force distribution assembly354A, which will be described in greater detail below. Each hanger323A includes an outboard member345and an inboard member346. Outboard member345includes a ribbed outboard wall347with an opening349formed therein for receiving bushing assembly232(FIG. 5), and a front wall348, which extends inboardly relative to the outboard wall. Inboard member346includes an inboard wall350with an opening352formed therein for receiving bushing assembly232, and a rear wall351, which extends inboardly relative to the inboard wall. Outboard and inboard hanger members345,346are arranged to form a channel353for receipt of beam231(FIG. 5) in hangers323A, and the beam is pivotally secured to the hanger via bushing assembly232, in a manner well-known in the art.

Each lower cross member354A,B includes an upper horizontal plate355, a lower horizontal plate356and a pair of parallel vertical walls358extending between the upper and lower plates, thereby forming a rectangular cross section. Adding to the structural stability of lower cross member354A,B is a diagonally-extending internal rib359. Upper plate355is formed with bolt holes357to enable mechanical attachment to the lower surface of main member lower flanges335,336, and to cross member lower flanges341,366. Preferably, hanger outboard and inboard members345,346are welded to an adapter plate360, which is a low-stress connection point at which a weld is sufficient. Adapter plate360is formed with bolt holes361that align with selective ones of bolt holes357formed in lower cross member lower plate356, thereby enabling mechanical attachment of hangers323A,B to the lower cross member lower plate. In this manner, each lower cross member354A,B, by being disposed below main members221and generally above hangers323A,B and extending transversely to the outboard edges of the main members, thereby interconnects the driver's side and passenger side hangers and main members. Preferably, a spacer plate367is disposed between each lower cross members354A,B and each respective front and rear cross member338,363to maintain uniform spacing

In order to enable second embodiment slider box320to interface with other structures associated with the heavy-duty vehicle (not shown) as well as for other purposes, the front and rear open ends of each main member321preferably receive an end bracket362

Second embodiment slider box320of the present invention provides a robust structure that is interconnected by mechanical fasteners, thereby reducing the potential for failure of welds in high-stress areas. Moreover, the use of lower cross member354A,B under main members321enables forces encountered by axle/suspension system230A,B (FIG. 5) to generally travel up each respective hanger323A,B and across the lower cross member for distribution across to the opposing main member More particularly, the attachment of lower cross members354A,B to respective hangers323A,B below main members321interrupts the transmission of forces from bushing assembly232(FIG. 5) up the hangers to the interface between the hangers and the main members, thereby reducing the moment arm along which the loading forces act, which in turn reduces the magnitude of the resultant forces. In this manner, forces encountered by the system are distributed among main members321and cross members338,363, rather than being isolated in a single interface between a hanger and respective main member, as in many prior art systems

Second embodiment slider box320of the present invention also provides a structure that reduces potential damage from extreme events. Lower cross member354A,B may optionally be designed to include an energy-absorbing component, such as vertical walls358and/or rib359, which absorbs the force of the impact from an extreme event and is designed to fail when it reaches its vertical force limit. By being mounted between each hanger323A,B and its respective main member321, each respective lower cross member354A,B deflects the force under heavy fore-aft loads, side loads and/or vertical loads to protect main members321, cross member pairs322A,B and other structural components from the stress caused by the force of the impact. After absorbing an impact, lower cross member354A,B can be replaced in a much more efficient and inexpensive manner than replacing main members321and cross member pairs322A,B.

In this manner, second embodiment slider box320provides a lighter weight heavy-duty vehicle subframe that includes components which are joined in a stronger and more dependable manner than by welding, efficiently distributes forces, and reduces potential damage from extreme events. It should be noted that most components of slider box320, including main members321, front cross members338, rear cross members363, outboard hanger member345, inboard hanger member346and lower cross members354A,B, preferably are made from a light-weight material, such as aluminum or an aluminum alloy, and include a uniform cross section that enables the components to be extruded or pultruded and then saw cut. Extruding, or pultruding, and saw-cutting aluminum components enables second embodiment slider box320to be lighter in weight than prior art slider boxes and relatively economical to manufacture.

It should be noted that, while each main member321of second embodiment slider box320is shown as a single unit having a rectangular cross section, the main members optionally may be of multiple pieces, such as two pieces. Turning toFIG. 15, an exemplary two-piece main member is indicated generally at370. A disadvantage of some single-piece main members having a rectangular cross section is the lack of easy access to the interior of the main member to fasten components to the main member In addition, it typically is more expensive to form, such as through extrusion or pultrusion, a main member having a cross section with a closed or hollow interior than a main member having a cross section that is open. Two-piece main member370overcomes these disadvantages

Two-piece main member370includes an inboard half371and an outboard half380. With additional reference toFIG. 16, inboard half includes an inboard vertical wall372with a horizontal upper flange373extending inboardly therefrom. A male interlock member374is formed on an outboard-facing surface of inboard vertical wall372near upper flange373. Inboard half371also includes an outboard partial wall376, which extends generally parallel to inboard wall372, and is connected to the inboard wall by a lower horizontal wall375. At the top of partial outboard vertical wall376, a horizontal flange377extends outboardly and a male interlock member378is formed on an inboard facing surface of the partial outboard wall near the horizontal flange

With additional reference toFIG. 17, outboard half380of two-piece main member370includes a partial vertical outboard wall381. At a bottom of partial outboard vertical wall381, an interlock channel383is formed, which receives and mechanically interlocks with male interlock member378formed on partial outboard wall376of inboard half371. Also at the bottom of partial outboard vertical wall381, a horizontal flange382extends outboardly from the wall and rests on horizontal flange377which extends from partial vertical wall376of inboard half371. Outboard half380further includes an upper horizontal wall384, extending inboardly from the top of outboard partial vertical wall381. Upper horizontal wall384includes an inboardly-extending flange385at its terminus, which rests on upper flange373of inboard vertical wall372. Upper horizontal wall384also includes an interlock channel386, which receives and mechanically interlocks with male interlock374formed on inboard vertical wall372.

In this manner, inboard and outboard halves371,380interlock with one another form an integral rectangular structure for main member370. Two-piece main member370thus enables easy access for the attachment of components. There is easy access to all surfaces of each of inboard and outboard halves371,380, which enables components to be fastened onto the inboard and outboard halves. More particularly, it is generally easy to insert a bolt on one side of inboard or outboard halves371,380, and just as easy to tighten a mating nut on the other side of the respective inboard or outboard half. Once components are respectively attached to inboard and outboard halves371,380, the halves are then interlocked, creating an integral main member370. Moreover, the constant cross-section and generally simple profile of inboard and outboard halves371,380enable two-piece main member370to be economically formed via extrusion or pultrusion.

An additional feature of two-piece main member370is the ability to more easily form outboard half380with a channel387to retain a low friction strip388. As mentioned above, in the prior art, as shown inFIG. 1, a low friction strip127is bolted to a main member121via fasteners128. Since low friction strip127typically is made of a polymer such as ultrahigh molecular weight polyethylene, its thermal expansion is different from that of a metal main member121. Over time, low friction strip127bulges between bolts128, which may cause portions of the strip to break off, creating an unsupported area for the movement of slider box120. Having such an unsupported area may contribute to cracking of certain components of slider box120. In addition, the use of bolts128to secure strip127may result in a less-than-flush installation of some bolts, or a backing out of the bolts, which may undesirably cause slider box120to jam.

The use of channel387reduces or eliminates these prior art problems, and also reduces or eliminates the cost and weight of bolts128. Channel387receives a corresponding interlocking member389formed on low friction strip388, which interlocks with and thereby secures the strip to main member370. In this manner, two-piece main member370secures low friction strip388without the use of bolts, or with a reduced number of bolts, and the use of channel387allows the strip to thermally expand at a different rate from that of main member370without bulging or breaking. Channel387is more easily and economically formed in the open cross section of outboard half380of two-piece main member370, as compared to forming the channel in the closed, or hollow, cross section of single-piece main member321.

Turning now toFIGS. 18-19, a third embodiment slider box for a heavy-duty vehicle of the present invention is shown and is indicated generally at400. Third embodiment slider box400generally is the same in structure and operation as first embodiment slider box220, with the exception that the third embodiment slider box employs front and rear force distribution assemblies402A,B, respectively, having shearable bolts404, rather than energy-absorbing component276of first embodiment front and rear force distribution assemblies258A,B, respectively. As a result, the differences between third embodiment slider box400and first embodiment slider box220now will be described in detail.

With reference toFIG. 18, third embodiment slider box400includes longitudinally extending, spaced-apart parallel main members221, and transversely extending, spaced-apart parallel front and rear cross member sets222A and222B, which extend between and interconnect the main members. Third embodiment slider box400includes a front force distribution assembly402A generally disposed under main members221and over front hangers406A, and which preferably extends transversely to the outboard edges of the main members. A rear force distribution assembly402B similarly is generally disposed under main members221and over rear hangers406B, and preferably extends transversely to the outboard edges of the main members.

Hangers406A,B of third embodiment slider box400are generally the same in structure and operation as hangers223A,B of first embodiment slider box220, with the exception that each hanger is shown with outboard and inboard hanger members408,410, respectively, which are secured by an overlap joint412and a mechanical fastener414, such as a bolt. More particularly, outboard hanger member408includes a front flange416, and inboard hanger member410includes a front flange418. Front flange416of outboard hanger member408and front flange418of inboard hanger member410form overlap joint412when the hanger members are assembled, and the overlap joint is secured by fastener414, as known to those skilled in the art.

With additional reference now toFIG. 19, and referring to front force distribution assembly402A by way of example, the force distribution assembly includes fore-aft spaced apart parallel, laterally-extending lower cross members270. Each lower cross member270is disposed adjacent an upper portion of hangers406A and includes, as in force distribution assembly258A of first embodiment slider box220, upper flange271. Upper flange271is formed with bolt holes272for mechanical attachment to the lower surface of main member lower flange242via vertically-disposed shearable bolts404(FIG. 18). Each lower cross member270also is bolted via horizontally-disposed bolts283to an upper portion of respective ones of flanges416,418and264,267of hangers406A.

An optional front reinforcing member420, which is similar to front reinforcing member273of first embodiment slider box220, nests in front of and is secured to each end of front lower cross member270. An optional rear reinforcing member422, which is similar to rear reinforcing member274of first embodiment slider box220, nests behind and is secured to each end of rear lower cross member270. Front and rear reinforcing members420,422provide additional robustness for force distribution assembly402A, and each preferably is formed with a rib424for additional structural support and to enable the connection of shock absorbers234(FIG. 5).

Maintaining the parallel relationship between lower cross members270, thereby forming a box-type structure, are a pair of plates426. More particularly, each one of plates426is disposed on the top surface of upper flange271of lower cross member270, generally above hangers406A, and inboardly of a respective one of main members221. Each plate426includes openings428that align with openings272in upper flange271of lower cross member270, and with a respective set of openings243formed in lower flange247of front cross member245(FIG. 7) or lower flange250of intermediate cross member248(FIG. 8). Aligned openings272,428and243receive shearable bolts404, which secure lower cross member270and plates426to front cross member245and to intermediate cross member248, thereby forming a rectangular structure about hangers406A for distribution of forces.

Third embodiment slider box400of the present invention provides a robust structure that is interconnected by mechanical fasteners, thereby reducing the potential for failure of welds in high-stress areas. Moreover, the use of force distribution assembly402A,B under main members221enables forces encountered by axle/suspension system230A,B (FIG. 5) to generally travel up each respective hanger406A,B and across lower cross members270for distribution across to the opposing main member. More particularly, the attachment of lower cross members270of force distribution assembly402A,B to respective hangers406A,B below main members221interrupts the transmission of forces from bushing assembly232(FIG. 5) up the hangers to the interface between the hangers and the main members, thereby reducing the moment arm along which the loading forces act, which in turn reduces the magnitude of the resultant forces. In this manner, forces encountered by the system are distributed among main members221and cross members245,248, rather than being isolated in a single interface between a hanger and respective main member, as in many prior art systems.

Third embodiment slider box400of the present invention also provides a structure that reduces potential damage from extreme events. Shearable bolts404, which connect force distribution assembly402A,B to main members221and cross members245,248, shear or fail when they teach a generally predetermined limit. Thus, when an impact is created by an extreme event, bolts404shear or fail under heavy fore-aft loads, side loads and/or vertical loads, thereby protecting main members221, cross member pairs222A,B and other structural components from the stress caused by the force of the impact. After bolts404shear, force distribution assembly402A,B and/or hangers406A,B can be replaced in a much more efficient and inexpensive manner than replacing main members221and cross member pairs222A,B.

In this manner, third embodiment slider box400provides a lighter weight heavy-duty vehicle subframe that includes components which are joined in a stronger and more dependable manner than by welding, efficiently distributes forces, and reduces potential damage from extreme events. It should be noted that most components of slider box400, including main members221, front cross members245, intermediate cross members248, rear cross members251, outboard hanger member408, inboard hanger member410, lower cross members270and plates426, preferably are made from a light-weight material, such as aluminum or an aluminum alloy, and include a uniform cross section that enables the components to be extruded or pultruded and then saw cut. Extruding, or pultruding, and saw-cutting aluminum components enables third embodiment slider box400to be lighter in weight than prior art slider boxes and relatively economical to manufacture.

As described above, first, second and third embodiments220,320,400of the slider box of the present invention provide a lighter weight, heavy-duty vehicle subframe that includes components which are joined in a stronger and more dependable manner than by welding, efficiently distributes forces, and reduces potential damage from extreme events. Of course, depending on design considerations, other cross-sectional configurations for the components of slider box220,320,400, than those described above may be used without affecting the overall concept or operation of the invention, such as plates, I-beams, C-beams, angled beams, X-shaped beams, rounded tubes, and the like

In addition, energy-absorbing component276,354A,B of first and second embodiments slider box220,320, respectively, may include different shapes and configurations than those shown and described above, such as a slanted plate, an X-shaped plate, a series of vertically-oriented walls, or any other crushable or sacrificial structure, and may include any suitable alignment or orientation, such as fore-aft, transverse, vertical, and/or angled, without affecting the overall concept or operation of the invention. Moreover, rather than using energy-absorbing component276,354A,B, a shearable structure, such as shearable bolts404of third embodiment slider box400, may be used, and may include different shapes and configurations with any suitable alignment or orientation, as described above for energy-absorbing component276,354A,B. Furthermore, combinations of energy-absorbing components276,354A,B and/or shearable structures404may be used without affecting the overall concept or operation of the invention.

It is to be noted that the number and arrangement of components may be adjusted from that as described above to suit particular design requirements, without affecting the overall concept or operation of the invention. In addition, while reference above has been made to the attachment of force distribution assemblies258A,B,354A,B,402A,B to main members221,321, hangers223A,B,323A,B,406A,B and selected components of cross member sets222A,B,322A,B, the force distribution assemblies may be attached to the main members and the hangers without attachment to the cross members, without affecting the overall concept of the invention.

It is also to be noted that, while reference has been made to bolts as mechanical fasteners, other mechanical fasteners, such as rivets, pins, tabs and the like, as well as combinations thereof, may be used. Moreover, the use of such mechanical fasteners may be used in selective combination with welds, so as to use welded connections in certain lower-stress areas and mechanical fasteners in higher stress areas. Further selective combination may be made with other methods of joining components, such as adaptive braces or interlocking joints.

Preferred embodiments slider box220,320,400have been shown and described with reference to exemplary ancillary components, and other ancillary components may be used without affecting the overall concept or operation of the invention. For example, while a pneumatic retractable pin mechanism224has been described, other types of retractable pin mechanisms as known the art may be used.

It is important to note that reference hereinabove has been made to preferred embodiments slider box220,320,400with the understanding that such reference is by way of example, and the present invention applies to heavy-duty vehicle primary frames, movable subframes and non-movable subframes. In addition, it is understood that the present invention finds application in all types of heavy-duty vehicle primary frames, movable subframes and non-movable subframes known to those skilled in the art, without affecting the concept or operation of the invention. Moreover, the present invention applies to primary frames, movable subframes and non-movable subframes that are capable of being outfitted with one, two, three or more axle/suspension systems. Also, while the present invention has been described with reference to a particular type of axle/suspension system, it applies to any suspension system or axle/suspension system known to those skilled in the art.

It is to be further understood that, while reference above has been made to the use of metals such as aluminum or an aluminum alloy with the present invention, other materials may be used. For example, other nonferrous metals and alloys thereof may be used. In addition, the present invention may also find applicability in uses with steel and other ferrous metals, particularly when it is desired to reduce dependency on welding. Moreover, the present invention may be used with composite materials or dissimilar metals that are not readily weldable, in which case adhesives or mechanical fasteners may be used to bond or secure the components.

Accordingly, the improved frame for heavy-duty vehicles is simplified, provides an effective, safe, inexpensive, and efficient structure which achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior art frames for heavy-duty vehicles, and solves problems and obtains new results in the art.

In the foregoing description, certain terms have been used for brevity, clarity and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the present invention has been described with reference to exemplary embodiments. It shall be understood that this illustration is by way of example and not by way of limitation, as the scope of the invention is not limited to the exact details shown or described. Potential modifications and alterations will occur to others upon a reading and understanding of this disclosure, and it is understood that the invention includes all such modifications and alterations and equivalents thereof.

Having now described the features, discoveries and principles of the invention, the manner in which the improved frame for heavy-duty vehicles is constructed, arranged and used, the characteristics of the construction and arrangement, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations are set forth in the appended claims.