The present invention relates generally to trailer assemblies, and, more particularly, to a trailer assembly which, when attached to the rear of a load-bearing vehicle, transfers a portion of the load from the rear wheel axle of the load-bearing vehicle to the wheel axle of the trailer assembly.
Roadway surfaces and bridges experience stresses due to the weight of load-bearing vehicles which travel the roadway systems. To lessen the detrimental effect of such traffic on the roadway systems, federal and state laws regulate load-bearing vehicles which travel federal and state roadways. These regulations dictate maximum loading per vehicle axle, which is based on the load-bearing capacity of roadway surfaces in the system, and minimum distance between load-bearing axles, which ensures that the vehicle's load is properly distributed over individual structural members of a bridge in the roadway system. Thus, vehicle weight restrictions generally are specified as a combination of load per axle and distance between axles.
To comply with such regulations, work vehicles that are designed to carry a substantial load often include some type of auxiliary axle that increases the vehicle's legal load-carrying capacity. Auxiliary axles generally include pusher axles, which typically are mounted forward of the vehicle's rear drive axle, and trailer or tag axles, which are mounted aft of the rear axle. Such auxiliary axles increase load-bearing capacity by redistributing the load on the vehicle's axles and/or extending the wheel base between load-bearing axles.
Pusher axles and many tag axles typically are deployable between a lifted or stowed position and a lowered or load-bearing position. Stowable configurations for tag axles generally employ hydraulically actuated piston assemblies that vertically pivot the axle relative to the vehicle to raise and lower the device. In the stowed position, the tag axle typically is positioned in a raised position at the rear of the vehicle. For some vehicles, tag axles in the stowed position can hinder loading and unloading tasks, thus rendering such arrangements impractical or unusable, particularly for vehicles have a flat loading bed.
Other trailer or tag axles may be configured as a detachable assembly. Typically, such assemblies include a pivotable connection that allows the assembly to pivot transversely relative to the vehicle such that the trailer axle can track behind the vehicle when turning. For some vehicles, however, transverse movement of the trailer relative to the vehicle can have detrimental effects on the stability of the vehicle during a turn as a result of the forces exerted by the trailer axle assembly on the vehicle frame which are necessary to redistribute the load on the axles. Further, transverse movement hinders maneuvers in a reverse direction. Thus, although a detachable trailer axle assembly does not present an obstacle to loading/unloading operations, other issues with respect to vehicle stability and maneuverability may arise.
Accordingly, it would be desirable to provide an auxiliary axle assembly that overcomes the aforementioned disadvantages of known auxiliary axle assemblies.
The present invention is directed toward a trailer assembly that, when attached to the rear portion of a load-bearing vehicle, transfers a portion of the load from the vehicle's rear wheel axle to the wheel axle of the trailer assembly.
In accordance with one aspect of the invention, a load-transferring assembly comprises a frame assembly having an auxiliary wheel axle, an abutment member connected to the frame assembly that has an abutment end and a free end, and an actuator assembly disposed between the free end of the abutment member and the frame assembly. When the frame assembly is connected to the rear portion of the vehicle and the abutment member abuts a vehicle abutment member that is disposed proximate the rear of the vehicle, transverse movement of the frame assembly relative to the vehicle is substantially restricted. Further, when the actuator assembly is actuated such that a lifting force is applied to the free end of the abutment member, a portion of the load on a rear axle of the vehicle is transferred to the auxiliary wheel axle of the frame assembly.
In accordance with another aspect of the invention, a load-transferring trailer assembly comprises a frame assembly that includes a wheel axle assembly and a pivotal assembly configured to detachably engage a rear portion of a load-bearing vehicle. The trailer assembly further comprises an elongate member connected to the frame assembly and extending between a static connection end and a free end. The static connection end is configured to form a static connection with the rear portion of the vehicle such that transverse movement of the frame assembly relative to the vehicle is substantially inhibited. A lifting member is arranged between the static connection end of the elongate member and the wheel axle assembly and is configured to apply a lifting force to the free end such that a portion of the load on the rear vehicle axle is transferred to the wheel axle assembly.
In accordance with yet another aspect of the invention, a combination is provided that comprises a load-bearing vehicle and a load-transferring trailer assembly connected to the vehicle. The trailer assembly comprises a frame assembly having an auxiliary wheel axle, a elongate member connected to the frame assembly, and an actuator assembly. The elongate member has a static connection end and a free end. The actuator assembly is disposed between the free end and the frame assembly and is configured to apply a lifting force to the free end such that a portion of the load on the rear axle of the load-bearing vehicle is transferred to the auxiliary wheel axle.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
Referring first to
In accordance with federal laws, the gross vehicle weight (i.e., the combined weight of the vehicle and its load) of a vehicle traveling on the interstate roadway system cannot exceed 80,000 lbs., the weight on any one axle cannot exceed 20,000 lbs., and the weight on any tandem axle cannot exceed 34,000 lbs. The maximum axle loads are further restricted by the federal bridge formula which dictates the maximum weight that may be borne by any two or more consecutive axles based on the inter-axle spacing. The bridge formula is as follows:
W=500[(L(N)/(N−1))+12(N)+36]
where W is the gross vehicle weight; L is the distance in rounded whole feet between the extreme of any group of two or more consecutive axles; and N is the number of axles in the group under consideration.
Thus, if the load-transferring assembly 10 is not attached to the vehicle 12 in
Referring now to
Turning now to
The pivot connection assembly 48 is configured to pivotally connect to the pair of side arms 42 and 44 and to pivotally engage with the engagement members 34 and 36 to secure the assembly 10 to the vehicle 12. In the exemplary embodiment illustrated in
Turning now to
An adjustable support leg 112 is disposed toward the abutment end 108 of the member 46 to stabilize the assembly 10 when not connected to the vehicle 12. A rotatable handle 114 allows for extension and retraction of the support leg 112, as desired.
The free end 110 of the abutment member 46 is positioned generally above the auxiliary axle 50. An actuator assembly is disposed between the free end 110 and the axle 50 and is operable to engage the abutment member 46 with the vehicle 12 in a manner that results in redistribution of a portion of the load on tandem axles 20 and 22 to the auxiliary axle 50 and the front axle 18, as will be described in detail below. In the exemplary embodiment illustrated in the Figures, the actuator assembly includes a pair of pneumatically activated air bags or bellows 116 and 118, such as air springs commercially available from Goodyear or Firestone. The free end 110 of the abutment member 46 terminates at a transverse portion 120 which connects the free end 110 to the top side of the bellows 116 and 118. The bottom side of the bellows 116 and 118 are attached to the ends of the side arms 42 and 44, which, in turn, are attached to the axle 50. The bellows 116 and 118 are pneumatically actuated via an air hose 122 which is detachably connectable to an air supply in the vehicle 12.
The amount of air pressure provided to the bellows 116 and 118 through the air hose 122 is based on the desired amount of load redistribution. In one embodiment, the amount of air pressure to actuate the bellows 116 and 118 is fixed in accordance with a setpoint established by control and regulator circuitry associated with the vehicle 12. In other embodiments, the control and regulator circuitry can be configured to have multiple setpoints that may be selected by an operator based on the gross vehicle weight. Alternatively, the control and regulator circuitry may be configured to determine a fixed setpoint based on monitored parameters, such as gross vehicle weight, tire pressure, etc. Or, the control and regulator circuitry may be configured to dynamically vary the amount of air pressure based on monitored parameters, such as terrain variations, load changes, direction of travel, etc.
Although the actuator assembly in the illustrated embodiment includes pneumatically actuated bellows to lift the abutment member 46, it should be understood that other types of actuator assemblies also are contemplated. Such assemblies may include hydraulically activated components, such as hydraulic pistons and cylinders, or any other type of structure that can lift the free end 110 of the abutment member 46 relative to the auxiliary axle 50.
Referring now to
Turning first to
To complete the engagement of the assembly 10 with the vehicle 12, the support leg is retracted via the handle 114 and the bellows 116 and 118 are pneumatically actuated through air hose 122 as shown in
The following example illustrates the resultant redistribution of the load. Given the interaxle spacings discussed with respect to
In the exemplary embodiment illustrated in the Figures, a shim 136 is attached to the surface 132 of the abutment end 108. Use of the shim 136 may be desirable to account for irregularities and mismatches between the abutment surfaces 132 and 134. Thus, the shim 136 may be positioned as needed to optimize the engagement between the surfaces 132 and 134.
Also in the exemplary embodiment illustrated in the Figures, the static engagement between the vehicle 12 and the load-transferring assembly 10 is an abutment. In alternative embodiments, the static engagement may be accomplished by other configurations. For example, the vehicle 12 may include a receiving cavity for receiving the abutment end 108 of the assembly 10. Such a cavity may be configured to lock the abutment end 108 into position while allowing the load-redistribution forces imparted from the lifting action to be transferred through the abutment member to the frame 26 of the vehicle 12.
As discussed, the engagement of the assembly 10 with the vehicle 12 prohibits transverse movement of the assembly 10 relative to the vehicle 12. Thus, to facilitate tracking of the assembly 10 with respect to the vehicle 12, which enables turning maneuvers and prevents scuffing and damage to the tires, the auxiliary axle 50 is configured as a self-steering axle.
Referring back to
The self-steering capability of the auxiliary axle 50, however, may hinder reverse maneuvers of the vehicle 12 when the assembly 10 is attached. For example, when attempting to back the vehicle 12 along a straight line, irregularities in the roadway surface may cause the wheels 52 and 54 to pivot. Thus, as the vehicle 12 continues to move in reverse, the tires on the wheels 52 and 54 may drag and scuff, potentially damaging the tires and/or the axle 50. Thus, in some embodiments, it may be desirable to lock the wheels 52 and 54 in a position suitable for straight movement in reverse.
Referring to
It also may be desirable to further facilitate reverse maneuverability by removing at least a portion of the load on the auxiliary axle 50. Removal of the load may be accomplished by relieving a portion of the lifting force on the free end 110 of the abutment member 46. In the exemplary embodiment, the lifting force is removed by partially bleeding the air from the bellows 116 and 118 whenever the lock pin assembly 152 is actuated. Bleeding the air may be triggered manually by the vehicle operation or may be synchronized with actuation of the lock pin assembly 152 by control electronics in the vehicle 12.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
Number | Name | Date | Kind |
---|---|---|---|
3298706 | Lyall | Jan 1967 | A |
3885808 | Derrwaldt | May 1975 | A |
4119156 | Wheeler et al. | Oct 1978 | A |
4165792 | Hohl et al. | Aug 1979 | A |
4335898 | Orosz et al. | Jun 1982 | A |
4449726 | Strifler et al. | May 1984 | A |
4783096 | Ramsey et al. | Nov 1988 | A |
5090495 | Christenson | Feb 1992 | A |
5163698 | Evens | Nov 1992 | A |
5320376 | Bojarski et al. | Jun 1994 | A |
5458355 | Young | Oct 1995 | A |
5474320 | Bojarski et al. | Dec 1995 | A |
5498021 | Christenson | Mar 1996 | A |
5516135 | Christenson | May 1996 | A |
5526890 | Kadowaki | Jun 1996 | A |
5540454 | VanDenberg et al. | Jul 1996 | A |
5549322 | Hauri | Aug 1996 | A |
5626356 | Harwood | May 1997 | A |
5816605 | Raidel, Sr. | Oct 1998 | A |
5823629 | Smith et al. | Oct 1998 | A |
5897123 | Cherney et al. | Apr 1999 | A |
6050578 | Beck | Apr 2000 | A |
6109379 | Madwed | Aug 2000 | A |
6116698 | Smith et al. | Sep 2000 | A |
6123347 | Christenson | Sep 2000 | A |
6135469 | Hulstein et al. | Oct 2000 | A |
6158750 | Gideon et al. | Dec 2000 | A |
6186266 | Marchant et al. | Feb 2001 | B1 |
6189901 | Smith et al. | Feb 2001 | B1 |
6247713 | Konop | Jun 2001 | B1 |
6273447 | Vande Berg | Aug 2001 | B1 |
6308793 | Eberling | Oct 2001 | B1 |
6311795 | Skotnikov et al. | Nov 2001 | B1 |
6311993 | Hulstein et al. | Nov 2001 | B1 |
6315311 | Mathiowetz | Nov 2001 | B1 |
6340165 | Kelderman | Jan 2002 | B1 |
6371227 | Bartlett | Apr 2002 | B2 |
6371499 | Konop | Apr 2002 | B1 |
Number | Date | Country | |
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20040007840 A1 | Jan 2004 | US |