Abstract:
The sweep tarpaulin has an upper sheath, a bottom sheath and an intermediate sheath. An upper tube is housed in the upper sheath. A lower tube is housed in the bottom sheath. An intermediate tube is housed in the intermediate sheath. The sides of the tarpaulin engage the container side walls. Left and right resilient members hold the upper tube in a loading position. The bottom sheath and the lower tube are supported on a reciprocating floor slat conveyor. Cargo and the lower tube move toward the rear during unloading. The left and right resilient members are deformed to release the upper tube. A winch returns the upper tube to the cargo receiving position. The left and right resilient members are deformed when the upper tube returns.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date of U.S. Provisional Application No. 61/047,874, titled SWEEP TARP, filed Apr. 25, 2008 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates cargo containers with reciprocating floor slat conveyors and more particularly a sweep tarp for sweeping particulate and granular materials from the floor slats at the same time the floor slats are reciprocated back and forth to unload a cargo container. 
     BACKGROUND OF THE INVENTION 
     Reciprocating floor slat conveyors are employed in cargo container bodies mounted on trucks as well as in trailers pulled by trucks. These conveyors are employed to improve efficiency and reduce the cost of moving bulk cargo by reducing the turn around time. 
     Cargo moved in containers, with reciprocating floor slat conveyors, includes agriculture products for human consumption as well as products for livestock consumption. Some products such as fodder for livestock stick together and substantially clean the upper surfaces of floor slats as the products are unloaded. A sweep to clean the cargo container is not required with these products. Products such as grains for human and livestock consumption tend to leave a layer of grain on each floor slat. It can take several minutes to manually sweep all the grain from floor slats that may be fifty feet long. If the cargo container is being unloaded several times per day the few minutes it takes to manually sweep the floor each time could reduce the number of loads transported per day. 
     A cargo container transporting the same cargo load after load could elect to forgo sweeping the floor slats. That election would result in transporting some cargo when returning for another load. Loading the cargo container with some cargo still in the container will reduce the quantity of cargo that is moved per trip. Over a period of time it could take several extra trips to transport the amount of cargo that would have been transported if the container had been emptied each time cargo was discharged. There is also the extra cost of transporting some cargo when the cargo container should be empty. 
     Some bulk cargo should not be contaminated with other cargo. Contamination such as mixing white beans with black beans is merely undesirable. Mixing grain for humans or livestock with a fertilizer for example could result in sick people or sick livestock. 
     The maximum weight that a cargo container can carry in one trip depends on the legal gross weight restrictions and the empty weight of the vehicle transporting the cargo. Transporting companies will pay a premium for cargo containers that will transport two or three hundred pounds of additional cargo per trip without a premature equipment failure. Prior to purchasing cargo containers, the cost of transporting the specific cargo that is generally transported, the distance the cargo is moved and other factors will be considered. One of the sweep tarps may or may not be purchased depending on the results of the calculations. 
     SUMMARY OF THE INVENTION 
     The sweep tarp assembly: includes a plate member adapted to be clamped to the front wall of a cargo container. A left vertical end plate is secured to the plate member and extends rearward from the plate member and away from the front wall. A right vertical end plate is secured to the plate member and extends rearward from the plate member and away from the front wall. A left resilient arm has a left base end anchored to said plate member outboard of the left vertical end plate and includes a left resilient arm portion extending upward and rearward from the left base to a left resilient arm free end. A right resilient arm has a right base end anchored to said plate member outboard of the right vertical end plate and includes a right resilient arm portion extending upward and rearward from the right base end to a right resilient arm free end. 
     A winch assembly includes a winch journaled on said plate member for rotation about a horizontal axis parallel to the front wall. A motor mounted on said plate member is between the left end plate and the right end plate and connected to the winch. The motor is operable to rotate the winch about the horizontal axis to wind a rope onto the winch. An idler spool is journaled on said plate member above the winch. The rope extends upward from the winch to the idler spool, between the plate member and the idler spool, over the top of the idler spool and then downward. A winch assembly cover plate is connected to the left vertical end plate and to the right vertical end plate. 
     A sweep tarpaulin has an upper sheath. A left side resilient arm aperture is in the upper sheath. A right side resilient arm aperture is in the upper sheath. A winch rope aperture is in the upper sheath mid way between the left side resilient arm aperture and the right side resilient arm aperture. A bottom sheath is provided on the tarpaulin. An intermediate sheath is between the upper sheath and the bottom sheath, a horizontal upper tube housed in the upper sheath, a horizontal lower tube housed in the bottom sheath and a horizontal intermediate tube housed in the intermediate sheath. 
     During loading of said cargo container the horizontal upper tube, is supported by the left side resilient arm with the left resilient arm free end extends through the left side resilient arm aperture. The right side resilient arm includes the right resilient arm free end extending through the right side resilient arm aperture. The lower tube in the bottom sheath is supported by said floor conveyor to the rear of said front end wall. The winch rope is secured to the horizontal upper tube through the winch rope aperture in the upper sheath; 
     During unloading of said cargo container the lower tube in the bottom sheath moves rearward with cargo. The upper tube and the upper sheath are pulled rearward and downward. The left side resilient arm and the right side resilient arm are deformed and release the upper tube. A left edge of the tarpaulin engages a left side wall of said cargo container. A right edge of said tarpaulin engages a right side wall of said cargo container. 
     After cargo is discharged, the motor is energized to rewind the rope on the winch, elevate the upper horizontal tube, and move the upper horizontal tube into engagement with the left resilient arm and into engagement with the right resilient arm. Continued upward movement of the upper horizontal tube deflects the left resilient arm free and deflects the right resilient arm free end upward until the left resilient arm free end and the right resilient arm free end snaps into a support positions under the upper horizontal tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The presently preferred embodiments of the invention are disclosed in the following description and in the accompanying drawings, wherein: 
         FIG. 1  is a schematic side vertical sectional view of the sweep tarp in a semi-trailer with the retraction housing removed to show the sweep tarp holder and parts broken away; 
         FIG. 2  is a schematic rear elevational view of a semi-trailer with the sweep tarp retained in a position for loading and the retractor housing removed; 
         FIG. 3  is a perspective view of the bottom and rear of the sweep tarp retainer and winch housing cover; 
         FIG. 4  is a perspective view of the left side and rear of the sweep tarp retainer and winch housing cover mounted on the front wall of a cargo container; 
         FIG. 5  is a perspective view similar to  FIG. 3  with the winch housing cover removed; and 
         FIG. 6  is a side view of the right side and rear of the sweep tarp retainer and winch with the winch cover removed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The sweep tarp retainer and winch assembly  10  includes a sweep tarp  12  a retainer system  14 , a winch assembly  16 , a winch  18  and winch housing cover  20 . The sweep tarp  12  is mounted in a cargo container  21  of a semi-trailer  24  with a left side wall  26 , a right side wall  28 , a front wall  30  and a floor  32 . A rear opening  34  can be closed by a left door  36  and a right door  38 . The left door  36  is attached to the rear edge of the left side wall  26  by hinges  40 . The right door  38  is attached to the rear edge of the right side wall  28  by hinges  42 . The edge of the left side wall  26  is reinforced by a left upper beam  44 . The upper edge of the right side wall  28  is reinforced by a right upper beam  46 . The upper edge of the front wall  30  is reinforced by an upper front wall beam  48 . Tarpaulin support beams  50  are secured to and supported by the top of the left side wall  26  and the top of the right side wall  28 . The tarpaulin support beams  50  are removable for loading cargo into the cargo container  21  of a semi-trailer  24  if necessary. The floor  32  of the cargo container  22  includes a plurality of floor slats  54 . The floor slats  54  are slideably supported by bearings  52  mounted on transverse I-beams  56 . The transverse I-beams  56  have ends that are fixed to side rails  58  on the bottom edges of the left side wall  26  and the right side wall  28 . A king pin  60  and a fifth wheel plate  62  are secured to the floor  32  of the semi-trailer  24  to the rear of the front wall  30 . The king pin  60  is connectable to the fifth wheel of a tractor vehicle. The fifth wheel plate  62  of the semi-trailer  24  sits and slides on the fifth wheel of a tractor. Each floor slat  54  is generally about three inches wide and extends the length of the cargo container  21 . A floor slat drive assembly (not shown) advances all of the floor slats  54  to the rear simultaneously and advances the cargo about twelve inches relative to rear opening  34  and away from the front wall  30 . The floor slat drive assembly then moves every third floor slat  54  connected to a first transverse drive beam forward about twelve inches while the remainder of the floor slats remains stationary. A second transverse drive beam then moves the one third of the floor slats  54 , on a first side of the floor slats connected to the first transverse drive beam, forward about twelve inches while the remainder of the floor slats remain stationary. A third transverse drive beam then moves the floor slats  54 , that are not connected to the first drive beam or the second drive beam, forward about 12 inches while floor slats driven by the first and second drive beams remain stationary. A slant board  64  connected to the side walls  26  and  28  and the front wall  30  covers the front ends of the floor slats  54  and keeps cargo from entering the space between the front ends of the floor slats and the front end wall  30 . The drive beams are then ready to have all the floor slats  54  moved simultaneously to the rear together with the cargo they support. The floor slats  54  continue to repeat the above steps until all of the cargo is discharged from the cargo container  21 . There are a number of other slat drives that can be employed to reciprocate floor slats  54 . 
     The sweep tarp  12  can be a tarp material  22  of polyester or nylon scrim embedded in vinyl or a sheet of net material. The net material is used for example to prevent sand from being blown from moving sand and gravel trucks. The tarp material  22  with a vinyl material prevents the passage of cargo with fine material and dust. The net material prevents the passage of most seeds and larger cargo particles and is relatively light weight. Sweep tarps  12  with tarp material  22  made from scrim embedded in vinyl as well as net material are both durable and flexible. 
     Sweep tarp  12  has an upper edge  66  with an upper sheath  68  formed by sewing or other procedures. An upper tube  70  is inserted into the sheath  68 . Three apertures  72 ,  74  and  76  are provided in the sheath  68  to expose the upper tube  70 . A center sheath  78  is formed in the sweep tarp  12 . The center sheath  78  receives a center tube  80 . A bottom sheath  82  is formed on the bottom edge  84  of the sweep tarp  12  by sewing or other procedures. A lower tube  86  is inserted into the bottom sheath  82 . The center tube  80  and the bottom tube  86  are parallel to the upper tube  70 . The upper tube  70 , the center tube  80  and the lower tube  86  hold the left edge  88  of the sweep tarp  12  adjacent to the inside surface of the left side wall  26 . The upper tube  70 , the center tube  80  and the lower tube  86  also hold the right edge  90  of the sweep tarp  12  adjacent to the inside surface of the right side wall  28 . The left edge  88  and the right edge  90  of the sweep tarp  12  are preferably in sealing contact with the adjacent side walls  26  and  28 . 
     The retainer system  14  for holding the sweep tarp  12  in position adjacent to the front wall  30  of the cargo container includes two resilient arms  92  with embedded plates in their base ends  94 . The base ends  94  of the resilient arms  92  are anchored to a rigid arm body  96  by a forward pin  98  and a rear pin  100 . The rigid arm body  96  is clamped to a bar  102  by bolts  104 . The bar  102  is secured to a plate member  106  with an integral upper flange  108  and an integral lower flanges  110 . The plate member  106  is clamped to the inside surface of the front wall  30  of a cargo container by bolts. The upper flange  108  is parallel to and below the upper front wall beam  48 . The plate member  106  is substantially vertical and parallel to the front wall  30 . The bar  102  is welded to the plate member  106  so that it extends upward and rearward from the plate member. In this position the forward pin  98  and the rear pin  100  both have a horizontal transverse axes and these axes are spaces apart in horizontal plane. The horizontal plane, that includes the axes of the forward pin  98  and the rear pin  100 , is perpendicular to the plate member  106  that supports the rigid arm body  96 . The resilient arm  92  is held in a position, by the forward pin  98  and the rear pin  100 , in which the resilient arm mid portion extends rearward and upward at an angle of about thirty degrees from horizontal. The free end  112  of the resilient arm  92  is curved upward from the thirty degree angle. The left retainer resilient arm  92  is mounted on the left end of the plate member  106  and the right retainer resilient arm  92  is mounted on the right end of the plate member and forms the retainer system  14 . The free end  112  of the left retainer resilient arm  92  extends through the aperture  72  in the sweep tarp material  22 , engages the upper tube  70  and urges the upper tube upward and forward. The free end  112  of the right retainer resilient arm  92  extends through the aperture  76  in the sweep tarp material  22 , engages the upper tube  70  and urges the upper tube upward and forward. The left and right retainer resilient arms  92  and their holder members form the retainer system  14  and hold the sweep tarp  12  in a position for loading a cargo container  21 . 
     The winch assembly  16  is mounted in a winch housing  120  formed by a left end plate  122  and a right end plate  124  secured to the plate member  106 . The left retainer resilient arm  92  is outboard of the left end plate  122 . The right retainer resilient arm  92  is outboard of the right end plate  124 . 
     The winch assembly  16  includes a winch spool  126  journaled on a bolt  128  by bearings. The bolt  128  passes through a channel shaped winch housing  130 . A driven spur gear  132  is attached to one side of the winch spool  126 . A drive pinion  134  is mounted on a shaft  136  journaled on the winch housing  130 . The drive pinion  134  meshes with the spur gear  132 . 
     An Ingersoll Rand® air drill  138  with a chuck  140  drives the shaft  136  and the drive pinion  134 . Air or motors drills  138  are available from other manufacturers. The air drill  138  can be replaced by an electric motor or by a hydraulic motor if desired. The power provided by an electric motor, a hydraulic motor or the air drill  138  can be selected to meet the demands of the trailer or van body in which the sweep tarp  12  is to be employed. A cargo container  21  that has a reduced inside width, height or length would most likely require less power for the winch  16 . A holder assembly  142  retains the body of the air drill  138  and keeps the body of the drill from rotating. The holder assembly  142  includes a resilient arm  144  that is secured to a rigid arm body  146  by two pins  148  and  150 . The resilient arm  144  of the holder assembly  142  engages the hand grip  152  of the air drill  138 . Air under pressure is supplied to the air drill  138  by a flexible line  154 . An inlet end of the flexible line  154  is connected to an air filter  156 . Water, oil and other contaminants are separated from air by the air filter  156  to thereby supplying clean dry air to the air drill  138 . An air line  158  is connected to a line fitting  160  mounted on the left end plate  122 , and an inlet port of the air filter  156 . The line fitting  160  is connected to a compressed air tank (not shown) of a vehicle brake system through a control valve. The air drill  138  drives the winch spool  126  in one direction only. There is no brake in the drive for the winch spool  126 . Friction in the winch assembly and winch drive system is minimized. 
     A nylon rope  161  is wound on the winch spool  126 . An idler spool  162  is journaled on a bolt  164  that passes through vertical plates  166  and  168  welded to the plate member  106 . The nylon rope  161  extends up from the winch spool  126 , around the front side of the idler spool  162  and out of the winch housing  120 . A cover plate  170  is clamped to the left end plate  122  and the right end plate  124  by screws. A top edge  172  of the cover plate  170  is above the integral upper flange  108  of the plate member  106 . A bottom edge  174  is below the integral lower flange  110 . 
     The nylon rope  161  passes rearward over the top of the idler spool  162  and out of the winch housing  120 , as stated above. A free end of the round nylon rope  161  is connected to the center of the upper tube  70 . An arcuate plate  176  has a rear end pivotally attached to the left vertical plate  166  and the right vertical plate  168  by a bolt  178 . The arcuate plate  176  extends forward and over the top of the idler spool  162  to retain the nylon rope  161  on the idler spool  162 . 
     During operation a valve is opened to supply air through an air filter  156  to the air drill  138 . Clean dry compressed air supplied to the air drill  138  rotates the winch spool  126  and winds up nylon rope  161 . The upper tube  70  of the sweep tarp engages the resilient arms  92  of the retainer system  14 . Both resilient arms  92  are forced upward until the upper tube  70  moves up above the free ends  112  of the resilient arms. The left arm  92  springs into the aperture  72  and the right arm  92  springs into the aperture  76  through sweep tarp  12 . The air drill  138  is overloaded and stops when the upper tube  70  contacts the rear surfaces of the vertical plates  166  and  168 . Closing the valve that supplies compressed air to the air drill releases torque on the winch spool  126 . The weight of the sweep tarp  12  together with the upper tube  70  and the center tube  80  rotates the winch spool  126  in a direction to unwind the nylon rope  161  and lowers the upper tube  70  onto the upper surface of both resilient arms  92 . The resilient arms  92  of the retainer system  14  hold the sweep tarp  12  in a cargo receiving position. In the cargo receiving position, the center tube  80  is slightly above the top of the slant board and the lower tube  86  is resting on the top of the floor slats  54  that form the floor  32 . 
     Movement of all of the floor slats  54  to the rear together with cargo carried by the floor slats  54  carries the lower tube  86  rearward. Rearward movement of the lower tube  86  pulls down on the upper tube  70  and increases the force exerted on the resilient arms  92  by the upper tube  70 . The winch spool  126  rotates freely to unwind the nylon rope  161  as the lower tube  86  is moved to the rear with the cargo. The resilient arms  92  bend as the lower tube  86  is moved reward by the floor conveyor and release the upper tube  70  from the retainer system  14 . 
     As cargo is discharged through the rear opening  34 , the sweep tarp  12  continues to move toward the rear opening  34  with the lower tube  86 . The sweep tarp  12  sweeps the upper surface of the floor slats  54  and carries loose material along. Cargo particles fall off the sweep tarp  12  as the sweep tarp passes to the rear of the floor  32 . Once the sweep tarp is free of cargo particles, air under pressure is supplied to the air drill  138 , the nylon rope  161 , with a round cross section, is rolled up on the winch spool  126  and the upper tube  70  is returned to the position supported on both resilient arms  92  as described above. The cargo container  21  is then ready to be filled with cargo again. 
     This disclosed embodiment is representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.