1. In a trailer suspension for mounting ground-engaging wheels to a vehicle frame, the suspension comprising a pair of beam assemblies, each beam assembly is adapted to be mounted to a different side of the vehicle frame and comprising a beam and two wheel-carrying axles mounted to each of the beams through an axle mounting assembly, the improvement comprising: at least two fluidly interconnected air springs mounted to each of the beams and adapted to support the vehicle frame thereon.
2. The trailer suspension according to claim 1 wherein the fluid interconnection comprises an unrestricted flow conduit so that the spring rate of each of the at least two air springs is relatively low during forward travel but relatively high during cornering.
3. The trailer suspension according to claim 2 wherein the internal diameter of the flow conduit is at least inch.
4. The trailer suspension according to claim 1 wherein the fluid interconnection comprises an unrestricted flow conduit so that the pressure in each of the at least two air springs is equalized during compression of one of the at least two air springs so that the spring rate of each of the at least two air springs acting independently is the spring rate of an air spring having the volume of the at least two air springs.
5. The trailer suspension according to claim 4 wherein the spring rate of each of the at least two air springs is the spring rate of each of the at least two air springs individually when both of the at least two air springs are compressed as, for example, during roll.
6. The trailer suspension according to claim 5 wherein the internal diameter of the flow conduit is at least inch.
7. The trailer suspension according to claim 1 wherein each of the at least two air springs has a roll stiffness of at least 6,000 pounds per inch.
8. The trailer suspension according to claim 1 wherein each of the at least two air springs contains an incompressible fluid.
9. The trailer suspension according to claim 8 wherein the incompressible fluid is water.
10. The trailer suspension according to claim 8 wherein the incompressible fluid is a mixture of water and glycol.
11. The trailer suspension according to claim 1 wherein each of the at least two air springs further comprises a solid insert.
12. The trailer suspension according to claim 1 wherein each of the at least two air springs has a plate mounted to an upper and lower end thereof and the diameter of each of the plates is greater than a diameter of each of the at least two air springs.
13. The trailer suspension according to claim 12 wherein the plates comprise a plurality of concentric rings.
14. The trailer suspension according to claim 1 wherein the beam further comprises at least one roll-restraint connector attached at one end to the beam and adapted to be attached at another end to the frame to limit the movement of the beam away from the frame.
15. The trailer suspension according to claim 14 wherein the at least one roll-restraint connector is attached to the center of the beam.
16. The trailer suspension according to claim 15 wherein the at least one roll-restraint connector includes a flexible connector.
17. The trailer suspension according to claim 16 wherein the flexible connector is a chain.
18. The trailer suspension according to claim 14 and further comprising at least one roll-restraint bumper.
19. The trailer suspension according to claim 18 wherein the at least one roll-restraint bumper comprises two roll-restraint bumpers.
20. The trailer suspension according to claim 19 wherein the roll-restraint bumpers are attached to the beam on either side of the at least one roll-restraint connector.
21. The trailer suspension according to claim 20 wherein the roll-restraint bumpers are formed of an elastomeric material.
22. The trailer suspension according to claim 21 wherein the elastomeric material is rubber.
23. The trailer suspension according to claim 18 wherein the at least one roll-restraint bumper comprises an air spring.
24. The trailer suspension according to claim 18 wherein the at least one roll-restraint bumper is attached to the beam at an end of the beam.
25. The trailer suspension according to claim 24 wherein the at least one roll-restraint bumper is formed of an incompressible material.
26. The trailer suspension according to claim 25 and further comprising a track bar mounted at one end to one of the beams and at another end adapted to be mounted to a frame, and wherein the track bar bracket forms at least one of the roll-restraint bumpers.
27. The trailer suspension according to claim 1 wherein the beam comprises an I-beam.
28. The trailer suspension according to claim 1 wherein the beam comprises a hollow box beam.
29. The trailer suspension according to claim 1 and further comprising a radius rod pivotably connecting one end of the beam to the vehicle frame.
30. The trailer suspension according to claim 29 wherein the radius rod has a length that limits the creep of the trailer to a negligible amount.
31. The trailer suspension according to claim 1 wherein the axle mounting assembly comprises a two-pin resiliently-bushed connection.
32. In a trailer suspension for mounting ground-engaging wheels to a vehicle frame, the suspension comprising a pair of beam assemblies, each beam assembly is adapted to be mounted to a different side of the vehicle frame and comprising a beam and two wheel-carrying axles mounted to each of the beams through an axle mounting assembly, the improvement comprising:
at least one roll-restraint connector attached at one end to the beam and adapted to be attached at another end to the frame to limit the movement of the beam away from the frame, and
at least one roll-restraint bumper mounted to the beam and adapted to limit the contact of the beam with the frame when the vehicle undergoes roll.
33. The trailer suspension according to claim 32 wherein the at least one roll-restraint connector is attached to the center of the beam.
34. The trailer suspension according to claim 32 wherein the at least one roll-restraint connector includes a flexible connector.
35. The trailer suspension according to claim 34 wherein the flexible connector is a chain.
36. The trailer suspension according to claim 35 and further comprising at least one roll-restraint bumper.
37. The trailer suspension according to claim 36 wherein the at least one roll-restraint bumper comprises two roll-restraint bumpers.
38. The trailer suspension according to claim 37 wherein the roll-restraint bumpers are attached to the beam on either side of the at least one roll-restraint connector.
39. The trailer suspension according to claim 38 wherein the roll-restraint bumpers are formed of an elastomeric material.
40. The trailer suspension according to claim 39 wherein the elastomeric material is rubber.
41. The trailer suspension according to claim 36 wherein the at least one roll-restraint restraint bumper comprises an air spring.
42. The trailer suspension according to claim 36 wherein the at least one roll-restraint bumper is attached to the beam at an end of the beam.
43. The trailer suspension according to claim 42 wherein the at least one roll-restraint bumper is formed of an incompressible material.
44. The trailer suspension according to claim 43 and further comprising a track bar mounted at one end to one of the beams and at another end adapted to be mounted to a frame, and wherein the track bar bracket forms at least one of the roll-restraint bumpers.
45. The trailer suspension according to claim 32 wherein the beam comprises an I-beam.
46. The trailer suspension according to claim 32 wherein the beam comprises a hollow box beam.
47. The trailer suspension according to claim 32 and further comprising a radius rod pivotably connecting one end of the beam to the vehicle frame.
48. The trailer suspension according to claim 47 wherein the radius rod has a length that limits the creep of the trailer to a negligible amount.
49. The trailer suspension according to claim 32 wherein the axle mounting assembly comprises a two-pin resiliently-bushed connection.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of depositing a two layer film having compressive stress, comprising:
depositing an initiation layer comprising silicon and carbon on a substrate in a chamber from a first gas mixture in the presence of a low frequency RF power, wherein the first gas mixture comprises a silicon and carbon-containing precursor; and then
turning on a high frequency RF power and depositing a bulk layer comprising silicon, carbon, and nitrogen on the initiation layer from a second gas mixture in the presence of the high frequency RF power, wherein the second gas mixture comprises the silicon and carbon-containing precursor, a nitrogen source, and hydrogen gas, and the bulk layer has a compressive stress of between about \u22120.1 GPa and about \u221210 GPa.
2. The method of claim 1, wherein the silicon and carbon-containing precursor is selected from the group consisting of alkylsilanes, alkylaminosilanes, and organosilazanes.
3. The method of claim 1, wherein the silicon and carbon-containing precursor comprises a silicon-containing compound selected from the group consisting of silane, disilane, and trisilylamine (TSA).
4. The method of claim 1, wherein the silicon and carbon-containing precursor comprises a carbon-containing compound selected from the group consisting of alkanes, alkenes, and alkynes.
5. The method of claim 1, wherein the silicon and carbon-containing precursor comprises a carbon-containing compound selected from the group consisting of alpha-terpinene (ATRP), toluene, limonene, pyran, cyclopentene, 1-methyl cyclopentene, and norbornadiene.
6. The method of claim 1, wherein the silicon and carbon-containing precursor further comprises nitrogen.
7. The method of claim 1, wherein the silicon and carbon-containing precursor further comprises oxygen.
8. The method of claim 1, wherein the silicon and carbon-containing precursor comprises trimethylsilane (TMS), methylsilane (MS), hexamethyldisilazane (HMDS), hexamethylcyclotrisilazane (HMCTZ), tris(dimethylamino)silane (TDMAS), tetra(dimethylamino)silane (TDMAS), bis(tertiary-butylamino)silane (BTBAS), or a combination thereof.
9. The method of claim 1, wherein the nitrogen source for the deposition of the bulk layer and for the deposition of the initiation layer comprises ammonia, hydrazine (N2H4), or dimethylhydrazine (N2C2H8).
10. The method of claim 1, wherein the oxygen source comprises N2O or O2.
11. The method of claim 1, wherein the silicon and carbon-containing precursor comprises octamethylcyclotetrasiloxane (OMCTS) or methyldiethoxysilane (MDEOS).
12. The method of claim 1, wherein the second gas mixture further comprises an inert gas selected from the group consisting of argon, xenon, helium and nitrogen.
13. The method of claim 1, wherein the initiation layer has a thickness of between about 5 \u212b and about 500 \u212b.
14. The method of claim 1, wherein the bulk layer has a thickness of between about 10 \u212b and about 10,000 \u212b.
15. The method of claim 1, wherein the substrate is positioned on a single substrate support in the chamber during the deposition of both the initiation layer and the bulk layer.
16. A method of depositing a two layer film having a compressive stress, comprising:
depositing an initiation layer comprising silicon, carbon, and nitrogen on a substrate in a chamber from a first gas mixture in the presence of a low frequency RF power, wherein the first gas mixture comprises a silicon and carbon-containing precursor and a nitrogen source and does not include hydrogen gas;
continuing the low frequency RF power;
turninq on a high frequency RF power; and then
depositing a bulk layer comprising silicon, carbon, and nitrogen on the initiation layer from a second gas mixture in the presence of the low and high frequency RF powers, wherein the second gas mixture comprises the silicon and carbon-containing precursor, the nitrogen source, and hydrogen gas, and the bulk layer has a compressive stress of between about \u22123 GPa and about \u221210 GPa.
17. The method of claim 16, wherein the substrate is positioned on a single substrate support in the chamber during the deposition of both the initiation layer and the bulk layer.
18. The method of claim 16, wherein the temperature of the substrate during the deposition of the initiation layer and the bulk layer is about 480\xb0 C. or less.
19. The method of claim 16, wherein the temperature of the substrate during the deposition of the initiation layer and the bulk layer is between about 480\xb0 C. and about 580\xb0 C.
20. The method of claim 16, wherein the high frequency RF power is turned on between the deposition of the initiation layer and of the bulk layer.
21. The method of claim 16, wherein the high frequency RF power operates at about 13.56 MHz, the low frequency RF power operates at about 350 kHz, and the combined power level of the low and high frequency RF powers is in the range of about 5 W to about 3000 W.
22. The method of claim 16, wherein the two layer film is a compressive stress nitride film.
23. The method of claim 1, wherein the first gas mixture further comprises a nitrogen source or an oxygen source.
24. The method of claim 1, wherein the initiation layer further comprises nitrogen or oxygen.