An excavating machine (10, 100) for making trenches in the ground including: • a hoisting engine provided with a mast having an upper end; • a steering tube mounted at the upper end of said mast and extending along the longitudinal axis oriented toward the ground, the steering tube including a stationary part that is fastened to the mast and a moving part that rotates relative to the stationary part around the longitudinal axis, the moving part of the steering tube having a coupling device; characterized in that the excavating machine comprises: • a chassis, suspended from the mast, having a lower part and an upper part, the lower part of the chassis bearing an excavating device while the upper part includes a coupling member coaxial to the longitudinal axis, the chassis being able to be moved along said longitudinal axis between: ∘ a coupled position in which the coupling member is coupled in rotation with the coupling device of the moving part of the steering tube so as to allow the pivoting of the chassis around the longitudinal axis due to the rotation of the moving part of the steering tube, and ∘ an uncoupled position in which the coupling member is uncoupled from the coupling device of the moving part of the steering tube, wherein the chassis is suspended from the mast by means of at least one lifting cable, wherein the movement of the lifting cable makes it possible to transition the chassis between its coupled position and its uncoupled position, wherein the excavating device includes two buckets mounted pivoting relative to the chassis, the buckets being actuated by an actuating mechanism (24, 124) arranged in the chassis, and wherein the actuating mechanism is actuated by an actuating cable which extends inside the coupling member. • a hoisting engine provided with a mast having an upper end; • a steering tube mounted at the upper end of said mast and extending along the longitudinal axis oriented toward the ground, the steering tube including a stationary part that is fastened to the mast and a moving part that rotates relative to the stationary part around the longitudinal axis, the moving part of the steering tube having a coupling device; characterized in that the excavating machine comprises: • a chassis, suspended from the mast, having a lower part and an upper part, the lower part of the chassis bearing an excavating device while the upper part includes a coupling member coaxial to the longitudinal axis, the chassis being able to be moved along said longitudinal axis between: ∘ a coupled position in which the coupling member is coupled in rotation with the coupling device of the moving part of the steering tube so as to allow the pivoting of the chassis around the longitudinal axis due to the rotation of the moving part of the steering tube, and ∘ an uncoupled position in which the coupling member is uncoupled from the coupling device of the moving part of the steering tube, wherein the chassis is suspended from the mast by means of at least one lifting cable, wherein the movement of the lifting cable makes it possible to transition the chassis between its coupled position and its uncoupled position, wherein the excavating device includes two buckets mounted pivoting relative to the chassis, the buckets being actuated by an actuating mechanism (24, 124) arranged in the chassis, and wherein the actuating mechanism is actuated by an actuating cable which extends inside the coupling member. ∘ a coupled position in which the coupling member is coupled in rotation with the coupling device of the moving part of the steering tube so as to allow the pivoting of the chassis around the longitudinal axis due to the rotation of the moving part of the steering tube, and ∘ an uncoupled position in which the coupling member is uncoupled from the coupling device of the moving part of the steering tube, wherein the chassis is suspended from the mast by means of at least one lifting cable, wherein the movement of the lifting cable makes it possible to transition the chassis between its coupled position and its uncoupled position, wherein the excavating device includes two buckets mounted pivoting relative to the chassis, the buckets being actuated by an actuating mechanism (24, 124) arranged in the chassis, and wherein the actuating mechanism is actuated by an actuating cable which extends inside the coupling member.