Abstract:
An apertured track and brace system for mounting a slider for adjusting the weight distribution of a semi-trailer. The apertured track is adapted to be mounted to both a semi trailer and to a carriage carrying a rear axle tandem, while a single type of brace is adapted to link the apertured track to other elements operable to slidably longitudinally position the axle tandem relative to the semi trailer itself.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to mechanisms for adjusting the position of the rear axles on a dual axle truck semi-trailer. In particular, the present invention is directed to a mechanism which permits the rapid and easy reallocation of weight on such a semi-trailer. 
     BACKGROUND OF THE INVENTION 
     Presently, there are over 1.1 million tractor trailers in operation in the United States. Tractor-trailers are subject to extensive Federal and state weight regulations. The violation of these weight regulations may result in fines and penalties to the operator or owner of the trailer. When a tractor-trailer combination is loaded very near to its legal limit, it will frequently be weighed at a roadside weigh-station. Under applicable regulations, the weight of the loaded trailer must be distributed under a calculation known as the “bridge formula”. The bridge formula determines the distribution of weight within the trailer and factors in the distance between the cab and the rear axles of the semi-trailer. When a truck is stopped on the road for a random weight measurement, it may have too much weight distributed over the rear axles. If the weight distribution falls outside the acceptable limits under the bridge formula, the truck will not be permitted to continue until the weight has been properly redistributed. 
     Rather than redistribute the weight within the trailer itself (which, depending on the cargo carried may be an impossible task), the operator customarily redistributes the weight by moving one or both of the axles of the semi-trailer. Unfortunately, the movement of the axles when a trailer is fully loaded is a difficult task. Most semi-trailers incorporate a wheeled tandem affixed to a carriage which is slidably adjustable along an apertured track on the trailer and which is retained in position by locking devices inserted into the apertures. 
     Presently, the vast majority of trailers are readjusted in the following manner: The operator (1) locks the rear tandem into place using the tandem axles brakes, (2) pulls a lever to disengage the locking pins, thus freeing the carriage to be adjusted along the trailer&#39;s length, (3) drives the tractor &amp; trailer forward or back to drag the trailer overthe locked tandem axles till they are in the new desired position, and (4) releases the lever pulled in step  2  so that the pins re-engage in the new desired set of apertures, again locking the carriage position relative to the trailer. 
     There are several problems associated with this method for readjusting the position of a rear tandem. Initially, this method relies largely upon trial and error before the correct positioning is achieved. Because this method relies upon the power of the vehicle tractor to slide the trailer, precise incremental movements of the trailer are usually not possible. Furthermore, it is frequently difficult to manually remove the locking pins from the apertures. This may be particularly problematic in cold or inclement weather, or when the pins are frozen, locked or rusted. 
     Various alternative methods have been devised to redistribute the weight of a semi-trailer. U.S. Pat. No. 3,203,711, for example, discloses a floating axle attachment in which a fifth floating axle is slid beneath the semi-trailer. This method is expensive and requires a specialized cab and trailer configuration. Another type of prior art device adjusts the location of the trailer coupling in order to effectuate weight distribution and transfer. See, U.S. Pat. Nos. 2,832,610; 4,662,670; 3,402,944 and 2,153,468. The devices disclosed in these patents are similarly complex and require expensive hydraulic cab configurations. U.S. Pat. No. 2,153,468 discloses a load redistribution system which incorporates a separate trailer dolly which rides on the main trailer bed. A third type of prior art device is directed to a system which adjusts the length of the chassis or trailer bed. See U.S. Pat. No. 2,371,261. This method is similarly expensive and requires specialized trailer configurations. 
     One quite effective mechanism of the prior art for solving the tandem adjustment problem is that of U.S. Pat. No. 5,346,233, which discloses a power-actuated device which is simple and safe to operate in adjusting the position of the rear tandem. 
     SUMMARY OF THE INVENTION 
     After the invention of the adjustment system of U.S. Pat. No. 5,346,233, there has still been a need to further simplify and standardize the mechanism by which various mechnical and hydraulic actuators may be attached to the trailer and tandem of the truck. In particular, there has been a need to reduce the number and type of parts comprising the system. In addition, there has been a need to reduce the number of hydraulic cylinders employed from two to one, thus eliminating expense, alignment issues, and maintenance load. Along with the other needs recognized by the inventor of U.S. Pat. No. 5,346,233, the present invention represents a simplification of manufacture, installation, operation, and maintenance for a slide system for adjustment of the position of the tandem relative to the trailer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side perspective view of the apertured track of the present invention, which is to be affixed to a semi-trailer having rear tandem axles. 
     FIG. 2 is a perspective view of the brace of the present invention. 
     FIG. 3 is a bottom perspective view of the assembly of four braces of the present invention, mounted to two pairs of two parallel apertured tracks of the present invention. 
     FIG. 4 is a bottom perspective view of the mounting of a hydraulic cylinder for longitudinal positioning of an axle tandem of a semi trailer, using six braces of the present invention, mounted to six apertured tracks of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The slider of the present invention is described with reference to the enclosed Figures wherein the same numbers are used where applicable. 
     The present invention is designed to be affixed to a tractor-trailer. Referring to FIG. 1, a side perspective view the apertured bracket  10  of the present invention is disclosed. The invention is preferably intended to be utilized on a double-axle semi-trailer. As noted in the Background of the Invention section, such trailers are subject to extensive federal and state weight regulation, and are required to specifically comply with weight restrictions calculated pursuant to the so-called “bridge formula”. 
     Referring now to FIG. 1, a trailer (not shown) has a tandem set of axles comprising eight wheels, which are retained on a carriage (all not shown.) The carriage is slidable along two parallel tracks, of which, one track  10  is depicted. (The tracks extend along opposite sides of the trailer.) In addition, up to three pairs of parallel tracks  10  are used on the underside of the trailer to mount the components of the present invention. Track  10  comprises a base flange  20 , having a plurality of mounting apertures  22  adapted to receive fastening means (not shown) for securing track  10  to the trailer. Track  10  also comprises a side flange  26 , at a substantially right angle to base flange  20 . Side flange  26  has a plurality of apertures  28  through which retaining members can be inserted and retracted in order to maintain and fix the position of the wheels, or through which permanent retaining members may be inserted to mount mechanical elements of the present invention. The apertures  28  on the trailer extend completely along the tracks. In this respect, the rear most apertures  28  on the trailer of the present invention are not sealed off. The trailer further includes a retractable landing gear (not shown) which is utilized to support the trailer in an upright position when the trailer is not supported by a cab. 
     Referring now to FIG. 2, there is depicted one brace  40  of the present invention. Brace  40  is comprised of a shaft  46 , terminating in a mounting flange  42  at each end thereof. Each mounting flange  42  is provided with a bore  44 , adapted to receive a retaining member (not shown) such as a bolt, locking pin, or the like, for engagement with an aperture  28  in track  10 . Bores  44  are parallel to each other, and are offset from each other in space because their attachment to shaft  46  is angled. The angels employed are complimentary to each other, however, the selection of the complementary angle is a matter of engineering choice, as is the length of shaft  46 , selected by one of skill in the art based on a variety of factors including the spacing of parallel tracks  10 , the weight and strength of the material from which brace  40  is fabricated, and the desired vertical distance from track  10  to the depending flange  42  when brace  40  is mounted to the trailer. 
     Referring now to FIG. 3, there is depicted a bottom perspective view of the assembly of four braces  40  of the present invention, mounted to two pairs of two parallel apertured tracks  10  of the present invention. Tracks  10  are mounted to the underside of a trailer in parallel pairs, but offset laterally by the depth of bore  44  of mounting flange  42 . In this manner, four braces  40  may be fixed to tracks  10  in a configuration such that, when their four depending flanges  42  have their bores  44  aligned in space, a pseudo-frustoconical or pryamidal configuration results. This pyramidal configuration provides a single attachment point for, for example, a hydraulic or pneumatic cylinder used to adjust the position of the axle tandem relative to the trailer. The pyramidal configuration is, when secured with bolts or similar fasteners, dimensionally stable and strong enough to withstand the forces required to reposition the axle tandem. The selection of the spacing of the legs of the pyramid of braces  40  with respect to each other is left to the engineering judgment of one skilled in the art, as alignment of the cylinder may be of critical interest. However, once secured, the pyramid of braces  40  need not be repositioned in normal operation. 
     Referring now to FIG. 4, a bottom perspective view of the mounting of a hydraulic cylinder  80  for longitudinal positioning of an axle tandem of a semi trailer (not shown), using eight braces  40  of the present invention, mounted to six apertured tracks  10  of the present invention is shown. Cylinder  80  is mounted at its forward end to a pyramid of 4 braces  40 , mounted to two pairs of two tracks  10 . An additional pair of tracks  10 , support an additional pair of braces  40  mounted to the rearmost end of cylinder  80 , to support and align the cylinder during operation. Piston  90  is extendably inserted into cylinder  80 , and is provided with a pair of braces  40  at its rearmost end, which are secured to the axle tandem (not shown). 
     In operation, a pneumatic system engages and retracts the trailer&#39;s locking pins which secure the axle tandem to the trailer. When retracted, a sensor permits energizing of a power source for actuation of piston  90  within cylinder  80  to reposition the axle tandem relative to the trailer. Once properly positioned, the pneumatic system re-engages locking pins to secure the axle tandem to the trailer in a fixed position. A “dead man switch” prevents operation of the system unless the operator maintains contact with the switch, in order to prevent injury to the operator and damage to the trailer or tandem. 
     It will be recognized by one skilled in the art that the system of the present invention, which employs only two structural members (bracket  10  and brace  40 ) to connect the various elements of the actuation system to both the trailer and the axle tandem provides many benefits including reduced manufacturing costs, design costs, storage costs, inventory complexity and costs, reduced shipping errors, and simplified installation and maintenance. 
     It is to be recognized by those skilled in the art that numerous embodiments fall within the spirit an scope of the present invention, and that the true nature and scope of the invention is to be determined with reference to the claims appended hereto. It is also the expressed condition placed on this application by the inventor that it is to be interpreted solely in accordance with the laws in effect as of the date of its filing, and that no later enacted law or decided case shall narrow the scope of the claims hereof in any way.