Centrally supported screen assembly

1. A vibratory separator comprising

a basket with a first side spaced-apart from a second side,

screen assembly apparatus mounted in the basket, the screen assembly apparatus having a central portion, a first screen side and a second screen side,

vibrating apparatus connected to the basket,

central support apparatus connected to the basket and positioned beneath and in contact with the central portion of the screen assembly apparatus,

pressing apparatus on the first side and second side of the basket for pressing down on the first screen side and on the second screen side of the screen assembly apparatus so that the central portion of the screen assembly apparatus is higher than the first screen side and the second screen side,

wherein said pressing apparatus comprises inflatable bladder apparatus,

wherein said screen assembly apparatus has a length and said central support apparatus has a length substantially equal to said length of said screen assembly apparatus,

wherein said screen assembly apparatus includes a channel member beneath said central portion thereof, said channel member for receiving part of said central support apparatus, and

wherein said screen assembly apparatus includes screen support apparatus for supporting screening material thereon, at least part of said central support apparatus contacting said screen support apparatus.

2. A vibratory separator comprising

a basket with a first side spaced-apart from a second side,

screen assembly apparatus mounted in the basket, the screen assembly apparatus having a central portion, a first screen side and a second screen side,

vibrating apparatus connected to the basket,

central support apparatus connected to the basket and positioned beneath and in contact with the central portion of the screen assembly apparatus,

pressing apparatus on the first side and second side of the basket for pressing down on the first screen side and on the second screen side of the screen assembly apparatus so that the central portion of the screen assembly apparatus is higher than the first screen side and the second screen side, and

wherein said screen assembly apparatus includes a channel member beneath said central portion thereof, said channel member for receiving part of said central support apparatus.

3. The vibratory separator of claim 2 wherein said pressing apparatus comprises inflatable bladder apparatus.

4. The vibratory separator of claim 2 wherein said inflatable bladder apparatus is pneumatically operable.

5. The vibratory separator of claim 2 wherein said screen assembly apparatus has a length and said central support apparatus has a length substantially equal to said length of said screen assembly apparatus.

6. The vibratory separator of claim 2 wherein the vibratory separator is a shale shaker for treating drilling fluid material from an earth wellbore.

7. The vibratory separator of claim 2 wherein said basket comprises at least one beam linking said first side and said second side, said central support apparatus on said at least one beam.

8. The vibratory separator of claim 2 wherein the central support apparatus has a top part for contacting the central portion of the screen assembly apparatus, the top part made of shock-absorbing material.

9. The vibratory separator of claim 8 wherein said top part has a hollow portion.

10. The vibratory separator of claim 2 wherein said screen assembly apparatus includes a flat piece of material within or connected to and beneath said central portion of said screen assembly apparatus.

11. The vibratory separator of claim 2 wherein said screen assembly apparatus includes screen support apparatus for supporting screening material thereon, at least part of said central support apparatus contacting said screen support apparatus.

12. The vibratory separator of claim 2 wherein said screen assembly includes screen support apparatus from the group consisting of frame, tubular members, strip support, and perforated plate.

13. The vibratory separator of claim 2 wherein said screen assembly apparatus includes a side member on each of the first screen side and the second screen side.

14. The vibratory separator of claim 13 wherein said side member is from the group consisting of bar, rod, hookstrip apparatus, and tube.

15. A vibratory separator comprising

a basket with a first side spaced-apart from a second side,

screen assembly apparatus mounted in the basket, the screen assembly apparatus having a central portion, a first screen side and a second screen side,

vibrating apparatus connected to the basket,

central support apparatus connected to the basket and positioned beneath and in contact with the central portion of the screen assembly apparatus, and

pressing apparatus on the first side and second side of the basket for pressing down on the first screen side and on the second screen side of the screen assembly apparatus so that the central portion of the screen assembly apparatus is higher than the first screen side and the second screen side,

wherein the central support apparatus has a top part for contacting the central portion of the screen assembly apparatus, the top part made of shock-absorbing material, and

wherein said top part has a hollow portion.