Pneumatic lift apparatus

1. A pneumatic lift apparatus comprising:

a main body including a body tube, with a cross-section of the body tube being neither a perfect circle nor a polygon, wherein the body tube includes an arcuate portion and a flat portion on an outer circumference thereof, with the arcuate portion and the flat portion contiguously connected to each other;

a restricting device slidably mounted on the body tube of the main body, wherein the restricting device includes a first end, a second end, a through-hole and a groove piercing therethrough longitudinally and a flat piece disposed in the groove, with the flat piece abutting with the flat portion of the body tube, with the body tube restricted not to rotate relative to the restricting device; and

a housing, wherein the restricting device is coupled to an end of the housing, with the main body inserted through the restricting device and received in the housing, with the main body fixed in the housing opposite to the restricting device.

2. The pneumatic lift apparatus as claimed in claim 1 , wherein the housing further comprises a receptacle having an outer wall, an orifice defined on the outer wall of the receptacle adjacent to the restricting device and a fixed element; wherein the restricting device comprises an orifice provided on an outer periphery of the second end of the restricting device axially and that does not communicate with the through-hole of the restricting device, with the fixed element inserted through the orifice of the housing means to the orifice of the restricting device.

3. The pneumatic lift apparatus as claimed in claim 1 , with the flat piece of the restricting device made of metal.

4. The pneumatic lift apparatus as claimed in claim 1 , with the restricting device made of plastic or rubber.

5. A pneumatic lift apparatus comprising:

a main body including a body tube, with a cross-section of the body tube being neither a perfect circle nor a polygon, wherein the body tube includes an arcuate portion and a flat portion on an outer circumference thereof, with the arcuate portion and the flat portion contiguously connected to each other;

a restricting device slidably mounted on the body tube of the main body, wherein the restricting device includes a first end, a second end, a first through-hole piercing therethrough longitudinally and a fixed pin inserted thereto and communicated with the first through-hole, with the fixed pin abutted against the flat portion of the body tube for preventing the body tube from rotating relative to the restricting device, with the body tube restricted not to rotate relative to the restricting device; and

a housing, wherein the restricting device is coupled to an end of the housing, with the main body inserted through the restricting device and received in the housing, with the main body fixed in the housing opposite to the restricting device.

6. The pneumatic lift apparatus as claimed in claim 5 , wherein the restricting device includes a second through-hole transversely piercing the second end of the restricting device, with the fixed pin disposed in the second through-hole, with the fixed pin abutting with the flat portion of the body tube with a line-contact.

7. The pneumatic lift apparatus as claimed in claim 5 , wherein the housing further comprises a receptacle having an outer wall, an orifice defined on the outer wall of the receptacle adjacent to the restricting device and a fixed element; wherein the restricting device comprises an orifice provided on an outer periphery of the second end of the restricting device axially and does not communicate with the through-hole of the restricting device, with the fixed element inserted through the orifice of the housing means to the orifice of the restricting device.

8. The pneumatic lift apparatus as claimed in claim 5 , with the restricting device made of plastic or rubber.

9. A pneumatic lift apparatus comprising:

a main body including a body tube, with a cross-section of the body tube being neither a perfect circle nor a polygon, wherein the body tube includes an arcuate portion and a flat portion on an outer circumference thereof with the arcuate portion and the flat portion contiguously connected to each other;

a restricting device slidably mounted on the body tube of the main body, wherein the restricting device includes a first end, a second end, a first through-hole piercing therethrough longitudinally and a restricting element installed to the bottom of the second end of the restricting device; wherein the restricting element includes a through-hole which is related to the through-hole of the restricting device longitudinally pierces the restricting element, with an arcuate portion and a flat portion forming the periphery of the through-hole of the restricting element and corresponding to the arcuate portion and flat portions of the body tube, respectively, with the body tube restricted not to rotate relative to the restricting device; and

a housing, wherein the restricting device is coupled to an end of the housing, with the main body inserted through the restricting device and received in the housing, with the main body fixed in the housing opposite to the restricting device.

10. The pneumatic lift apparatus as claimed in claim 9 , wherein the housing further comprises a receptacle having an outer wall, an orifice defined on the outer wall of the receptacle adjacent to the restricting device and a fixed element; wherein the restricting device comprises an orifice provided on an outer periphery of the second end of the restricting device axially and does not communicate with the through-hole of the restricting device, with the fixed element inserted through the orifice of the housing means to the orifice of the restricting device.

11. The pneumatic lift apparatus as claimed in claim 9 , with the restricting element made of metal.

12. The pneumatic lift apparatus as claimed in claim 9 , with the restricting device made of plastic or rubber.

13. A pneumatic lift apparatus comprising:

a main body including a body tube, with a cross-section of the body tube being neither a perfect circle nor a polygon;

a restricting device slidably mounted on the body tube of the main body, with the body tube restricted not to rotate relative to the restricting device; and

a housing comprising a limited portion formed therein and an aperture defined on a center of the limited portion, wherein the main body further comprises a connected rod slidably received in the body tube and a connected element for fixing the connected rod to the housing, wherein the restricting device is coupled to an end of the housing, with the main body inserted through the restricting device and received in the housing, with the main body fixed in the housing opposite to the restricting device;

wherein while the main body is received in the housing, the body tube is abutted against the limited portion and the connected rod is engaged with the aperture via the connected element.

14. The pneumatic lift apparatus as claimed in claim 13 , with the connected rod including a connected end inserted through the aperture for engaging with the connected element.