A shed forming machine, of the mechanical cam or dobby type, for a weaving machine, said machine comprising: - output levers oscillating about a common shaft centered on a longitudinal axis; - a cover defining an outlet opening through which the output levers pass; - a frame that, along with the cover, delimits an interior volume of the machine; and - a sealing device (40, 52, 54) intended for closing the outlet opening of the hood and comprising sealing struts stacked along the common shaft and arranged on either side of the output levers, as well as at least one seal (52, 54), each sealing strut comprising: - a band that extends from a first end, located near the frame, to a second end, located near the cover, and comprises two longitudinal edges (408, 410), orthogonal to the longitudinal axis of the common shaft and configured to abut at least one longitudinal edge of the band of an adjacent sealing strut; and - an inner radial edge that defines a common shaft passage opening centered on a primary axis coincident with the longitudinal axis of the common shaft at least when the machine is in the weaving configuration, characterized in that - the seal (52, 54) extends along a main direction (A52, A54) parallel to the longitudinal axis of the common shaft and abuts a fixed part (4, 6) of the machine; - each sealing strut is provided with at least one groove (416, 436) which extends parallel to its primary axis and opens out on each side of the sealing strut; - the grooves of the sealing struts of the sealing device (40, 52, 54) together define a channel (G2, G4) for receiving a heel (522, 542) of the seal. said machine comprising: - output levers oscillating about a common shaft centered on a longitudinal axis; - a cover defining an outlet opening through which the output levers pass; - a frame that, along with the cover, delimits an interior volume of the machine; and - a sealing device (40, 52, 54) intended for closing the outlet opening of the hood and comprising sealing struts stacked along the common shaft and arranged on either side of the output levers, as well as at least one seal (52, 54), each sealing strut comprising: - a band that extends from a first end, located near the frame, to a second end, located near the cover, and comprises two longitudinal edges (408, 410), orthogonal to the longitudinal axis of the common shaft and configured to abut at least one longitudinal edge of the band of an adjacent sealing strut; and - an inner radial edge that defines a common shaft passage opening centered on a primary axis coincident with the longitudinal axis of the common shaft at least when the machine is in the weaving configuration, - output levers oscillating about a common shaft centered on a longitudinal axis; - a cover defining an outlet opening through which the output levers pass; - a frame that, along with the cover, delimits an interior volume of the machine; and - a sealing device (40, 52, 54) intended for closing the outlet opening of the hood and comprising sealing struts stacked along the common shaft and arranged on either side of the output levers, as well as at least one seal (52, 54), each sealing strut comprising: - a band that extends from a first end, located near the frame, to a second end, located near the cover, and comprises two longitudinal edges (408, 410), orthogonal to the longitudinal axis of the common shaft and configured to abut at least one longitudinal edge of the band of an adjacent sealing strut; and - an inner radial edge that defines a common shaft passage opening centered on a primary axis coincident with the longitudinal axis of the common shaft at least when the machine is in the weaving configuration, characterized in that - the seal (52, 54) extends along a main direction (A52, A54) parallel to the longitudinal axis of the common shaft and abuts a fixed part (4, 6) of the machine; - each sealing strut is provided with at least one groove (416, 436) which extends parallel to its primary axis and opens out on each side of the sealing strut; - the grooves of the sealing struts of the sealing device (40, 52, 54) together define a channel (G2, G4) for receiving a heel (522, 542) of the seal. - the seal (52, 54) extends along a main direction (A52, A54) parallel to the longitudinal axis of the common shaft and abuts a fixed part (4, 6) of the machine; - each sealing strut is provided with at least one groove (416, 436) which extends parallel to its primary axis and opens out on each side of the sealing strut; - the grooves of the sealing struts of the sealing device (40, 52, 54) together define a channel (G2, G4) for receiving a heel (522, 542) of the seal.