Patent ID: 8777801

Claim:
A planetary gear train ( 6 ) for an aircraft ( 1 ) capable of fixed-point flight, comprising: a sun gear ( 7 ) that can turn about a first axis (A) and comprises a plurality of first teeth ( 11 ); a fixed crown wheel ( 8 ) comprising a plurality of second teeth ( 12 ); and at least two planetary gears ( 9 a , 9 b , 9 c , 9 d , 9 e ), each comprising a plurality of third teeth ( 13 ); said planetary gears ( 9 a , 9 b , 9 c , 9 d , 9 e ) each meshing with said crown wheel ( 8 ) and said sun gear ( 7 ) and being able to turn about respective second axes (B), which are in turn able to turn about said first axis (A); said planetary gear train ( 6 ) being characterized in that: at least two of said third teeth ( 13 ) simultaneously mesh with respective second teeth ( 12 ) and a further two of said third teeth ( 13 ) simultaneously mesh with respective first teeth ( 11 ); said third teeth ( 13 ) comprise a first side ( 16 a ) and a second side ( 16 b ), which have, respectively, a first pressure angle (α 1 ) and a second pressure angle (α 2 ) different from one another; and the number (ZP) of said third teeth ( 13 ) of each of said planetary gears ( 9 a , 9 b , 9 c , 9 d , 9 e ) is different from the absolute value of the semidifference ((ZC-ZS)/2) between the number (ZS) of said first teeth ( 11 ) of said sun gear ( 7 ) and the number (ZC) of said second teeth ( 12 ) of said crown wheel ( 8 ).