Trailer overhead door system

1. A trailer overhead door system for a trailer having a door opening, a floor opposite a roof, and a first side wall opposite a second side wall, and a door opening header above said door opening, the trailer overhead door system comprising:

a trailer door for enclosing said door opening, said trailer door comprising a door top rail, a left vertical side and a right vertical side;

a left track for slidable receipt with said left vertical side of the door, said left track extending along said first vertical side of said door opening and along a portion of the roof of the trailer;

a right track for slidable receipt with said right vertical side of the door, said right track extending along said second vertical side of said door opening and along a portion of the roof of the trailer;

a counterbalance system for maintaining said trailer door in an open position, closed position, and positions therebetween, said counterbalance system comprising at least one spring, a shaft, at least one cable drum, and at least one lifting cable, said lifting cable comprising a first end and a second end; and

at least one return pulley for guiding said lifting cable,

wherein said first end of said lifting cable runs generally parallel to said roof and is connected to said door top rail, wherein said lifting cable extends around said return pulley, and wherein said second end of said lifting cable connects to said at least one cable drum.

2. The trailer overhead door system of claim 1 , wherein said trailer door comprises a single membrane trailer door.

3. The trailer overhead door system of claim 1 , wherein said first end of said lifting cable is connected to said door top rail via at least one lifting bracket.

4. The trailer overhead door system of claim 3 , wherein said trailer door comprises a single membrane trailer door.

5. A trailer overhead door system for a trailer having a door opening, a floor opposite a roof, and a first side wall opposite a second side wall, said door opening having a pair of vertical sides and a door opening header above said door opening, the trailer overhead door system comprising:

a single membrane trailer door for enclosing said door opening, said trailer door comprising a door top rail, a left vertical side and a right vertical side;

a left track for slidable receipt with said left vertical side of the door, said left track is curved and extends from a first proximal end adjacent said first side wall and then horizontally along a portion of said roof to a first distal end;

a right track for slidable receipt with said right vertical side of the door, said right track is curved and extends from a second proximal end adjacent said second side wall and then horizontally along a portion of said roof to a second distal end;

a counterbalance system for maintaining said single membrane trailer door in an open position, closed position, and positions therebetween, said counterbalance system comprising at least one torsion spring, a shaft, at least one cable drum, and at least one lifting cable, said lifting cable comprising a first end and a second end; and

at least one return pulley for guiding said lifting cable,

wherein said torsion spring is wound about said shaft and said cable drum is attached to said shaft, said first end of said lifting cable is attached to said cable drum, said second end of said lifting cable extends in a first direction about said return pulley, then in a second direction, attaching to said door top rail of the single membrane door.

6. The trailer overhead door system of claim 5 , wherein said second end of said lifting cable is connected to said door top rail via at least one lifting bracket.

7. A trailer overhead door system for a trailer having a door opening, a floor opposite a roof, and a first side wall opposite a second side wall, said door opening having a pair of vertical sides and a door opening header above said door opening, the trailer overhead door system comprising:

a single membrane door for enclosing said door opening, said trailer door comprising a door top rail, a left vertical side and a right vertical side, said door top rail further comprising a first lifting bracket and a second lifting bracket;

a left track for slidable receipt with said left vertical side of the door, said left track is curved and extends from a first proximal end adjacent said first vertical side and then horizontally along a portion of said roof to a first distal end;

a right track for slidable receipt with said right vertical side of the door, said right track is curved and extends from a second proximal end adjacent said second vertical side and then horizontally along a portion of said roof to a second distal end;

a counterbalance system for maintaining said trailer door in an open position, closed position, and positions therebetween, said counterbalance system comprising a torsion spring, a shaft, said shaft further comprising a first end and second end, a first cable drum and second cable drum, and a first lifting cable and second lifting cable, said first lifting cable further comprising a first end and second end, said second lifting cable further comprising a first end and second end;

a first return pulley for guiding said first lifting cable; and

a second return pulley for guiding said second lifting cable,

wherein said torsion spring is wound about said shaft, said first cable drum is attached to said first end of the shaft, said second cable drum attached to said second end of the shaft, said first end of the first lifting cable is attached to the first cable drum, said second end of the first lifting cable extends in a first direction about the first return pulley, then in a second direction, wherein the first lifting cable attaches to said first lifting bracket, said first end of the second lifting cable is attached to the second cable drum, said second end of the second lifting cable extends in a first direction about the second return pulley, then in a second direction, wherein the second lifting cable attaches to said second lifting bracket.