Piston assembly

1. A piston assembly comprising:

a piston comprising a head end flange and a crank end flange;

a rod having a head end shoulder and a crank end shoulder, wherein the head end shoulder of said rod contacts the head end flange of said piston and the crank end shoulder of said rod contacts the crank end flange of said piston;

a nut engaged with said rod, wherein the head end flange of said piston is disposed between said nut and the head end shoulder of said rod; and

a collar engaged with said piston, wherein the crank end shoulder of said rod is disposed between said collar and the crank end flange of said piston.

2. The piston assembly of claim 1 wherein said piston further comprises:

a cavity within said piston; and

a hole through said piston that provides access to said cavity.

3. The piston assembly of claim 2 wherein said hole is disposed within a groove formed circumferentially about said piston.

4. The piston assembly of claim 1 wherein said piston further comprises a first aperture through the crank end flange and a second aperture through the head end flange, wherein said first and second apertures are aligned and sized such that the head end shoulder of said rod passes through the second aperture but not the first aperture.

5. The piston assembly of claim 1 wherein said nut threadedly engages said rod.

6. The piston assembly of claim 1 wherein said collar threadedly engages said piston.

7. The piston assembly of claim 1 wherein said piston is a unitary body.

8. The piston assembly of claim 1 wherein said piston is constructed from a single casting.

9. A piston assembly method comprising:

inserting a rod through a head end flange and a crank end flange of a piston;

capturing the head end flange of the piston between a nut engaged with the rod and a head end shoulder disposed on the rod; and

capturing a crank end shoulder of the rod between the crank end flange of the piston and a collar engaged with the piston.

10. The method of claim 9 wherein the nut threadedly engages the rod.

11. The method of claim 9 wherein the collar threadedly engages the piston.

12. The method of claim 9 wherein the piston is a unitary body.

13. The method of claim 9 wherein the piston is constructed from a single casting.

14. A piston assembly comprising:

a rod having a first shoulder and a second shoulder, wherein the first shoulder has a smaller diameter than the second shoulder;

a first flange disposed against the first shoulder;

a second flange disposed against the second shoulder;

a cylindrical body connected to said first flange and said second flange;

a nut engaged with said rod and disposed adjacent to said first flange; and

a collar engaged with said second flange and disposed adjacent to the second shoulder of said rod.

15. The piston assembly of claim 14 further comprising a cavity defined by said cylindrical body, said first flange, and said second flange.

16. The piston assembly of claim 15 further comprising one or more holes through said cylindrical body that provide access to said cavity.

17. The piston assembly of claim 16 wherein said one or more holes are disposed within a groove formed circumferentially about cylindrical body.

18. The piston assembly of claim 14 wherein said nut threadedly engages said rod.

19. The piston assembly of claim 14 wherein said collar threadedly engages said second flange.

20. The piston assembly of claim 14 wherein said cylindrical body, said first flange, and said second flange form a unitary body.

21. The piston assembly of claim 20 wherein the unitary body is constructed from a single casting.