The present disclosure refers to a boom mounting assembly for attachment to an agricultural machine, comprising a primary frame (12)； and a boom support frame (1) configured to support a boom (10) and suspended from the primary frame (12) such that the boom support frame (1) can pivot in a transverse plane around a longitudinal axis of rotation provided in a pivot point. The boom support frame (1) comprises a first sub-frame (2) connecting to the primary frame (12)； a second sub-frame (3) supported by the first sub-frame (2) in support sections provided, in a transverse direction, on opposite sides of the pivot point； and an actuator (7) connecting to the first (2) and second (3) sub-frames and operable such that the support sections can be moved relative to the pivot point, thereby, in a transverse direction increasing a distance between the pivot point and a support section on one side of the pivot point and, at the same time, decreasing a distance between the pivot point and a support section on an opposite side of the pivot point and vice versa. Further, a method for controlling operation of a boom mounting assembly attached to an agricultural machine is provided.La présente invention concerne un ensemble de montage de flèche destiné à être fixé à une machine agricole, comprenant un cadre principal (12) ； et un cadre de support de flèche (1) configuré pour supporter une flèche (10) et suspendu au cadre principal (12) de telle sorte que le cadre de support de flèche (1) peut pivoter dans un plan transversal autour d'un axe de rotation longitudinal situé dans un point de pivotement. Le cadre de support de flèche (1) comprend un premier cadre secondaire (2) se raccordant au cadre principal (12) ； un second cadre secondaire (3) supporté par le premier cadre secondaire (2) dans des sections de support disposées, dans une direction transversale, sur des côtés opposés du point de pivotement ； et un actionneur (7) se raccordant aux premier (2) et second (3) cadres secon
