Abstract:
A dual dump trailer assembly ( 10 ) is provided which provides for operating two end dump trailers ( 12, 14 ) with a single cab ( 16 ). The operation is possible by use of a movable pedestal ( 30 ) having a fifth wheel mounted on the forward end dump trailer ( 12 ). The pedestal ( 30 ) is in the rearward, trailing position to attach the rearward end dump trailer ( 14 ) at the fifth wheel ( 110 ) on the pedestal for towing. Upon arrival at the dump site, the rearward end dump trailer ( 14 ) can be dumped and then detached from the forward end dump trailer ( 12 ). The pedestal ( 30 ) mounting the fifth wheel will move forward to a forward, dumping position, permitting the contents of the forward end dump trailer ( 12 ) to be dumped.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    In hauling materials over the highways, particularly materials within dump trailers, there is a conflict between the desire to carry as much material as possible and weight limitations regulating the gross weight of a highway vehicle established in many jurisdictions within the United States and foreign countries. The gross weight permitted under law is typically related to the vehicle size, and particularly to the vehicle wheel base. In particular, the gross weight permitted is often related to the number of axles on the vehicle and the wheel base defined as the distance between selected axles. In the common semi-trailer type configuration including a power unit and a trailer, the wheel base can be measured a number of ways. The wheel base can be measured between the leading and trailing axles of the trailer, between the leading drive axle of the power unit and the trailing axle of the trailer or between the steering axle of the power unit and the trailing axle of the trailer.  
           [0002]    A need continues to exist for optimizing the load carrying capability of a vehicle while complying with the relevant laws governing vehicle weight. By carrying fewer, heavier loads, the operator can save expenses as well as reduce impact in neighborhoods by passage of the vehicles.  
         SUMMARY OF THE INVENTION  
         [0003]    In accordance with one aspect of the present invention, a dual dump trailer assembly is provided which includes a cab, a first end dump trailer for attachment to said cab with the first end dump trailer having a pedestal for movement between a forward, dumping position and a rearward, towing position and a second end dump trailer for attachment to said first end dump trailer at the pedestal in the rearward, towing position. In accordance with another aspect of the present invention, the pedestal on the first end dump trailer mounts a fifth wheel.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    A more complete understanding of the invention and its advantages will be apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:  
         [0005]    [0005]FIG. 1A is a side view of a dual dump trailer assembly forming a first embodiment of the present invention illustrating the rear dump trailer in dumping position;  
         [0006]    [0006]FIG. 1B is a side view of the dual dump trailer assembly illustrating the rearward end dump trailer removed from attachment to the pedestal on the front end dump trailer after having dumped its load;  
         [0007]    [0007]FIG. 1C illustrates the dual dump trailer assembly with the pedestal on the forward end dump trailer moved into the forward, dumping position;  
         [0008]    [0008]FIG. 1D illustrates the forward end dump trailer moved into the dumping position;  
         [0009]    [0009]FIG. 1E illustrates the dual dump trailer assembly with the rearward end dump trailer attached to the pedestal of the forward end dump trailer so that the dual dump trailer assembly can be driven down the highway;  
         [0010]    [0010]FIG. 1F is a side view of the cab and forward end dump trailer illustrating the pedestal in the forward, dumping position;  
         [0011]    [0011]FIG. 2 is a side view of the cab and forward end dump trailer with the pedestal in the rearward, towing position;  
         [0012]    [0012]FIG. 3 is a side view of the cab and forward end dump trailer with the trailer body in the tiled position for dumping the payload;  
         [0013]    [0013]FIG. 4 is a side view of a portion of the forward end dump trailer illustrating the wedge structure;  
         [0014]    [0014]FIG. 5 is a top view of a portion of the forward end dump trailer along line  5 - 5  in FIG. 4 to illustrate the locking structure;  
         [0015]    [0015]FIG. 6 is a vertical cross section in the forward end dump trailer taken along line  6 - 6  in FIG. 4;  
         [0016]    [0016]FIG. 7 is a side view of a cab and a frame type forward end dump trailer with the pedestal in the rearward position for towing forming a first modification of the present invention;  
         [0017]    [0017]FIG. 8 is a side view of the cab and the frame type forward end dump trailer illustrating the pedestal in the forward position for dumping operation;  
         [0018]    [0018]FIG. 9 is a side view of a portion of the frame type forward end dump trailer;  
         [0019]    [0019]FIG. 10 is a cross-sectional view of the frame and forward dump trailer taken along line  10 - 10  in FIG. 9; and  
         [0020]    [0020]FIG. 11 is a plan view of the locking mechanism of the frame and forward dump trailer.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, and in particular to FIGS.  1 A- 1 E, a dual dump trailer assembly  10  is illustrated which provides for operating two end dump trailers, a forward end dump trailer  12  and rearward end dump trailer  14 , with a single cab or power unit  16 . At least the forward end dump trailer  12  is provided with a pedestal  30  which can be moved on the forward end dump trailer  12  between a forward, dumping position and a rearward, trailing position. While trailering both end dump trailers, the pedestal  30  is in the rearward position as illustrated in FIG. 1E, allowing the rearward end dump trailer  14  to be towed thereby. Rearward end dump trailer  14  attaches to a fifth wheel  110  forming part of the pedestal  30  for towing. When dumping, the rearward end dump trailer  14  is dumped first, as seen in FIG. 1A. The rearward end dump trailer  14  is then removed from the assembly as seen in FIG. 1B. The pedestal  30  is moved forward relative the rest of the forward end dump trailer  12  until the pedestal is in the forward position completely underneath the forward end dump trailer  12  and forward of the end of the forward end dump trailer  12  as seen in FIG. 1C to allow the forward end dump trailer to be dumped, as seen in FIG. 1D.  
         [0022]    While the rearward end dump trailer  14  does not require a sliding pedestal  30 , it is preferred that the trailers  12  and  14  are identical and therefore interchangeable in the role of the forward or rearward end dump trailer. However, if desired, rearward end dump trailer  14  can be any style of end dump trailer suitable for attachment to fifth wheel  110 . A sliding pedestal  30  of the type contemplated is disclosed in the present inventor&#39;s prior issued U.S. Pat. No. 4,531,753 issued Jul. 30, 1985, U.S. Pat. No. 4,660,843, issued Apr. 28, 1987, and U.S. Pat. No. 4,865,341, issued Sep. 12, 1989. All three patents are incorporated by reference herein in their entirety.  
         [0023]    With reference to FIG. 1F and FIG. 2, additional details of the cab  16  and forward end dump trailer  12  will be described. The rearward end dump trailer  14  can be identical to forward end dump trailer  12  and therefore need not be described. The forward end dump trailer  12  is a frameless style. The end dump trailer  12  is in the horizontal position shown in FIG. 1F and 2 during loading of the payload and while traveling on the highway. When the payload is to be dumped, a hydraulic mechanism in the forward end dump trailer  12  will pivot the trailer body  17  to an angle up to approximately 50 degrees from the horizontal to dump, as seen in FIG. 3.  
         [0024]    As set forth in the background of the invention, local jurisdictions have restrictions on gross vehicle weight based on certain lengths between axles on a vehicle. The trailer assembly  10  illustrated has a steering axle  20  and forward and rearward drive axles  22  and  24  on the cab  16 . Forward end dump trailer has a forward trailing axle  26 , a middle trailing axle  27  and a rearward trailing axle  28 , while the rearward end dump trailer  14  also has a forward trailing axle  26 , a middle trailing axle  27  and a rearward trailing axle  28 . The axles  26 ,  27  and  28  are part of rear wheel unit  18  which is mounted to pedestal  30 . The various distances between these axles can be optimized, partly by providing for the appropriate position of the pedestal  30  in the rearward, towing position, to provide an optimal load for the given weight restriction laws in a particular jurisdiction.  
         [0025]    In the normal construction of an end dump trailer, the rear wheel unit  18  must be positioned relative to the body as illustrated in FIGS. 1F and 3 to permit the trailer body  17  to pivot upward for dumping of the payload. If the rear wheel unit  18  was permanently mounted behind the dumping lift  100  of the trailer body  17  seen in FIG. 3, a protective shield or ramp would be required to protect the unit  18  from damage from the payload during dumping. Also, the maximum dumping angle of the trailer body  17  generally decreases as wheel unit  18  is positioned further back on the trailer  12 .  
         [0026]    In accordance with the teachings of the present invention, the pedestal  30  supporting the rear wheel unit  18  on the forward end dump trailer  12  is slidable along a portion of the length of the trailer between the forward, dumping position shown in FIGS. 1F and 3 and the rearward, towing position shown in FIG. 2. By sliding the pedestal  30  into the rearward, towing position, the wheel base X on the dump trailer assembly  10  has been increased.  
         [0027]    With reference to FIGS. 4 and 6, the pedestal  30  slidably contacts the bottom of channels  32  forming part of the frame  33  of the trailer body  17  and located on either side of the trailer body. Polyethylene pads  34  are bolted to the surface  36  of the pedestal  30  by bolts  37  proximate the channels  32  to reduce friction between the trailer body  17  and pedestal  30  and also to provide a cushioning action between the two elements.  
         [0028]    Forward frame wedges  38 , middle frame wedges  40  and rearward frame wedges  42  are positioned on either side of the trailer body  17  on the channels  32 . The frame wedges  38 ,  40  and  42  cooperate with the forward pedestal wedges  44  and rearward pedestal wedges  46 . In the forward position of pedestal  30  shown in FIGS. 1F and 3, the forward pedestal wedges  44  engage the forward frame wedges  38  and the rearward pedestal wedges  46  engage a portion of the middle frame wedges  40 . In the rearward position illustrated in FIGS. 2 and 4, the forward pedestal wedges  44  are engaged with a portion of the middle frame wedges  40  and the rearward pedestal wedges  46  are engaged with the rearward frame wedges  42  to wedge the pedestal to the frame  33  in the rearward position.  
         [0029]    A forward locking assembly  48 , shown in FIG. 5, is mounted on frame  33  and cooperates with locking holes  50  formed in the pedestal  30  as shown in FIG. 4. The forward locking assembly  48  comprises a dual double acting cylinder  52  having pistons  54  and  56  shown in their retracted positions in FIG. 5. Locking wedges  58  and  60  are positioned at the end of pistons  54  and  56 , respectively. When the pedestal is moved into the forward position by locking the brakes on the rear wheel unit  18  of the forward end dump trailer  12 , and backing the cab  16 , the pistons  54  and  56  can be activated to drive the locking wedges  58  and  60  into the locking holes  50 . The wedges  58  and  60  have wedge surfaces  62  which act to wedge the pedestal wedges into the frame wedges when the pistons  54  and  56  move outwardly from the dual cylinder  52 . In the forward position, the dual dump trailer assembly  10  is adapted for the dumping of the payload of the forward end dump trailer  12 .  
         [0030]    A rearward locking assembly  66  is also mounted on the frame  33 . The rearward locking assembly  66  comprises the identical elements of forward locking assembly  48  but with the wedge surfaces  62  oriented in the direction opposite those in the forward locking assembly  48 . To move the pedestal  30  into the rearward position, the brakes on unit  18  are again locked and the cab  16  is moved forward. The rearward locking assembly  66  will act to wedge the pedestal wedges into the frame wedges when the pedestal  30  is in the rearward position for travel on a public highway.  
         [0031]    The pedestal  30  is aligned with the frame  33  by polyethylene blocks  68  having guide surfaces  70  as best shown in FIG. 6. The blocks  68  are secured to angle member  72  which are bolted to a flange  74  on each side of the frame  33  as best seen in FIG. 6. The angle member  72  and blocks  78  can be adjusted inwardly toward the pedestal or outwardly from the pedestal by adjusting screws  76 . Typically, a small gap  78  will be maintained between the guide surfaces  70  and the pedestal  30 . The polyethylene blocks  68  will maintain the pedestal  30  aligned with the frame  33  both in the forward and rearward positions and while moving between the positions.  
         [0032]    In the preferred construction, the dual cylinders  52  in both the forward and rearward locking assemblies  48  and  66  are double acting and operated by air pressure. This will permit the locking assemblies to be operated by the vehicle operator from within the cab  16 .  
         [0033]    The assembly  10  described above and illustrated in FIGS.  1 - 6  is commonly referred as having frameless end dump trailers, as the main frame and the trailer body of end dump trailers  12  and  14  are integral. FIGS.  7 - 11  illustrate a dual dump trailer assembly  200  which incorporates a frame type forward end dump trailer  202  and a rearward frame type end dump trailer  203  (not shown but identical to forward frame type end dump trailer  202 ). However, in all other respects, the assembly  200  operates in the same manner as assembly  10 . Forward frame end dump trailer  202  is identical to trailer  203 , and only trailer  202  will be described. The trailer  202  includes a separate horizontal rigid frame  204  which is attached at its forward end to the cab  16  and a trailer body  206  which is pivoted near the dumping end of the rigid frame  204  for pivotal motion between a horizontal traveling position, as shown in FIG. 7, and a tilted dumping position as shown in FIG. 8.  
         [0034]    The trailer  202  is provided with a pedestal  208  which performs the identical function of pedestal  30  discussed previously in permitting dumping of the trailer body  206  when in the forward position shown in FIG. 8 and for trailering when in the rearward position shown in FIG. 7.  
         [0035]    As best seen in FIG. 10, the pedestal  208  slidably contacts the bottom of channels  210  forming part of the frame  204 . Polyethylene pads  212  are bolted to the upper surface  214  of the pedestal  208  to reduce friction between the trailer frame  204  and pedestal  208  and also to provide a cushioning action between the two elements. An adjustable side bearing  216  is mounted on the pedestal by a threaded bolt  218 . The threaded bolt  218  can be rotated to move the side bearing  216  into contact with the side of the frame  204  to insure the pedestal will slide along the length of the frame without jamming.  
         [0036]    As best seen in FIG. 9, the trailer  202  includes forward frame wedges  220 , middle frame wedges  222  and rearward frame wedges  224  positioned on either side of the frame  204  on the channels  210 . The pedestal  208  is provided with forward pedestal wedges  226  and rearward pedestal wedges  228  on either side of pedestal  208 . When the pedestal  208  is in the forward position, the forward pedestal wedges  226  engage the forward frame wedges  220  and the rearward pedestal wedges  228  engage a portion of the middle frame wedges  222 . In the rearward position, illustrated in FIG. 9, the forward pedestal wedges  226  engage a portion of the middle frame wedges  222  and the rearward pedestal wedges  228  are engaged with the rearward frame wedges  224 .  
         [0037]    With reference to FIG. 11, the locking assembly  230  is illustrated. The locking assembly  230  is mounted on the pedestal  208  and includes an air cylinder  232  having a piston  233 . A pivot plate  234  is pivotally mounted to the pedestal at pivot  235  and to the end of the piston  233 . Locking wedge  236  is connected to plate  234  by a pivotal link  238 . A second pivot plate  240  is pivoted to the pedestal and connected to the plate  234  by a pivotal link  242 . The opposite locking wedge  244  is connected to plate  240  by a pivotal link  246 . As can be seen, when air is provided to cylinder  232  to extend the piston  233 , the wedges  236  and  246  are retracted. When air is provided to the cylinder to retract piston  233 , the wedges extend outwardly for locking the pedestal either in the forward position against the forward lock plate assemblies  248  or in the rearward position with rear lock plate assemblies  250 . In operation, the vehicle  200  is operated in an identical manner to the dump trailer assembly  10  described hereinabove.  
         [0038]    Although several embodiments of the present invention have been illustrated in the accompanying drawings and described in the foregoing detailed description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions of parts and elements without departing from the scope and spirit of the invention.