Supporting mechanism for a papermaking machine dewatering blade

1. A pneumatically actuated moveable doctoring device for a paper machine forming section, the device comprising:

a base member adapted to be supported by a papermaking machine structure;

a blade support with a fabric contact element;

a single pneumatic air tube having first and second attachments on opposing sides of the pneumatic air tube, the first attachment engages the base member and the second attachment engages the blade support, the pneumatic air tube being configured for connection to a pressurized air source and a vacuum source to extend or retract the blade support relative to the base member; and

a linkage arrangement connected between the blade support and the base member, the linkage arrangement including at least first and second links located between the base member and the blade support, the links each having a pivotal connection to the base member and provide for a fixed orientation of the blade support relative to the base member as the pneumatic air tube extends the blade support or retracts the blade support guided by the linkage arrangement.

2. The doctoring device of claim 1 , wherein the linkage arrangement forms a four-bar linkage arrangement, with each of the first and second links having a pivotal connection to the blade support.

3. The doctoring device of claim 2 , wherein the pivotal connections each include a pin that extends through openings in the base member and the blade support.

4. The doctoring device of claim 3 , wherein the openings each include a bushing therein, and the pins extend through the bushings.

5. The doctoring device of claim 2 , wherein a distance between the pivotal connections of the base member is equal to a distance between the pivotal connections on the base support.

6. The doctoring device of claim 1 , further comprising the pressurized air source and the vacuum source connected to the single pneumatic air tube by a valve arrangement.

7. The doctoring device of claim 1 ; further comprising a least one flexible cover connected between the base member and the blade support that encloses the linkage arrangement.

8. The doctoring device of claim 1 , wherein the first and second attachments on the single pneumatic air tube have a T-shape and are integrally formed on the opposing sides of the single pneumatic air tube, and the base member and the blade support each include a corresponding T-shaped receptacle for a positive fit connection to the single pneumatic air tube.

9. The doctoring device of claim 1 , wherein the fabric contact element is connected to the blade support with a positive fit connection.

10. A forming section of a papermaking machine, comprising:

at least two rolls;

a forming fabric that is supported on the at least two rolls; and

a pneumatically actuated moveable doctoring device, including

a base member adapted to be supported by a papermaking machine structure;

a blade support with a fabric contact element that extends in a cross direction across a width of the fabric;

a single pneumatic air tube having first and second attachments on opposing sides of the pneumatic air tube, the first attachment engages the base member and the second attachment engages the blade support, the pneumatic air tube being configured for connection to a pressurized air source and a vacuum source to extend or retract the blade support relative to the base member into and out of contact with the forming fabric; and

a linkage arrangement connected between the blade support and the base member, the linkage arrangement including at least first and second links located between the base member and the support member, the links each have a pivotal connection to the base member and provide for a fixed orientation of the blade support relative to the base member as the pneumatic air tube extends the blade support into contact with the forming fabric or retracts the blade support guided by the linkage arrangement.

11. The forming section of claim 10 , further comprising at least a second one of the pneumatically actuated moveable doctoring devices.

12. The forming section of claim 10 , wherein the linkage arrangement forms a four-bar linkage arrangement, with each of the first and second links having a pivotal connection to the blade support.

13. The forming section of claim 10 , wherein the pivotal connections each include a pin that extends through openings in the base member and the blade support.

14. The forming section of claim 10 , further comprising additional linkage arrangements that are spaced apart from one another in the cross direction.

15. The forming section of claim 10 , wherein the base member includes an undercut recess for connection to a frame of the forming section.

16. A pneumatically actuated moveable doctoring device for a paper machine forming section, the device comprising:

a base member adapted to be supported by a papermaking machine structure;

a blade support with a fabric contact element;

a pneumatic air tube having first and second attachments on opposing sides of the pneumatic air tube, the first attachment engages the base member and the second attachment engages the blade support, the pneumatic air tube being configured for connection to a pressurized air source and a vacuum source to extend or retract the blade support relative to the base member, the first and second attachments on the pneumatic air tube have an enlarged end section with a smaller base and are integrally formed on opposing surfaces of the pneumatic air tube, and the base member and the blade support each include a corresponding undercut receptacle for a positive fit connection to the pneumatic air tube; and

a linkage arrangement connected between the blade support and the base member, the linkage arrangement including at least first and second links located between the base member and the blade support, the links each have a pivotal connection to the base member and provide for a fixed orientation of the blade support relative to the base member as the pneumatic air tube extends the blade support or retracts the blade support guided by the linkage arrangement.