Control device (50) for controlling the variation of the angle of attack of the blades (8) of an anti-torque rotor (4) for an aircraft (1) capable of hovering, comprising:
- a control element (16) sliding along a first axis (A) with respect to a shaft (6) of said anti-torque rotor (4) and rotatable integrally with said shaft (6);
- said control element (16), moreover, being operatively connected to a plurality of said blades (8) articulated on said shaft (6) in order to cause, in use, their rotation around respective second axes (B) following a translation of said element (16) itself along said first axis (A);
- a control rod (10) axially sliding along said first axis (A) with respect to said shaft (6) and angularly fixed with respect to said first axis (A);
- and
- a rolling bearing (17) interposed between said control rod (10) and said control element (16), sliding along said first axis (A) with respect to said shaft (6) and integrally with said control rod (10), and configured to allow the relative rotation of said control element (16) with respect to said control rod (10) about said first axis (A);
- said rolling bearing (17) comprising, in turn:
- a first ring (30) that is rotatable integrally with said control element (16) about said first axis (A);
- a second ring (31) radially internal to said first ring (30) with respect to said first axis (A) and sliding integrally with said control rod (10) along said first axis (A);
- and
- a plurality of rolling bodies (32), which are interposed between said first and second rings (30, 31) and adapted to roll on respective tracks (33, 34) of said first and second rings (30, 31);
- said control device (50) further comprising:
- a threaded element (51) screwed onto said control rod (10) and cooperating with said second ring (31) to constrain it axially with respect to said control rod (10);
- a bushing (52) coupled in an angularly and axially fixed manner to said threaded element (51), and in an angularly fixed manner to said control rod (10);
- and
- first connecting means (70) adapted to connect said bushing (52) to said control rod (10);
- said control rod (10) comprising a first profile (71, 71′) and said bushing (52) comprising a second profile (72, 72′);
- said threaded element (51) comprising a third profile (61);
- characterized in that it comprises:
- second connecting means (60) distinct from said first connecting means (70) and adapted to connect said bushing (52) to said threaded element (51);
- said first connecting means (70) comprising a first shape coupling (70) and said second connecting means (60) comprising a second shape coupling (60);
- said first profile (71, 71′) comprising a plurality of first interfaces (71b;
- 71b′) and said second profile (72, 72′) comprising a plurality of second interfaces (72b, 72b′);
- said first and second interfaces (71b, 72b;
- 71b′, 72b′) being coupled with one another and defining said first shape coupling (70);
- said bushing (52) comprising a fourth profile (62);
- said third profile (61) comprising a plurality of third interfaces (64) and said fourth profile (62) comprising a plurality of fourth interfaces (65);
- said third and fourth interfaces (64, 65) being coupled with one another and defining said second shape coupling (60);
- wherein said first and second interfaces (71b, 72b;
- 71b′, 72′) are even and said third and fourth interfaces (64, 65) are odd;
- or
- wherein said first and second interfaces (71b, 72b;
- 71b′, 72′) are odd and said third and fourth interfaces (64, 65) are even;
- wherein the number of said first and second interfaces (71b, 72b;
- 71b′, 72b′) is not a multiple of the number of said third and fourth interfaces (64, 65) and in that the number of said third and fourth interfaces (64, 65) is not a multiple of the number of said first and second interfaces (71b, 72b;
- 71b′, 72′).