Trench-digging machine

Claim 1

A trencher comprising a carrying and traction vehicle (1) having two longitudinal ends, a sleeve-like frame, a boom (3) and a digging chain (4), said boom (3) being slidingly disposed in said sleeve-like frame (5), and said digging chain circulating around said boom; said sleeve-like frame being pivotably mounted for vertical swinging movement about a substantially horizontal axis (X--X') at said one longitudinal end of the vehicle (1) and being swingable about said axis between: a lowered operative position, in which the sleeve-like frame is tilted toward the ground (6) and the boom (3) is at a reduced inclination to the vertical and the bottom part of the boom (3) is engaged in the ground (6); and an inoperative transport position in which the frame (5) is raised toward the vehicle (1) and the boom (3) is slid upward within the frame and disengaged from the ground, the lower part of the sleeve-like frame (5) having members (5a) adapted to bear on the ground (6) in said lowered operative position, thereby receiving and transmitting to the ground the forces transmitted to the frame during digging, and allowing the frame to slide along the ground, the boom (3) comprising a rectangular-section tubular element (8) and the frame (5) comprising a sleeve-like part (9) of companion cross-section, the tubular element (8) being slidingly received in the part (9), the tubular element (8) of the boom (3) having on opposite surfaces (8a, 8b) thereof perpendicular to the direction (D) of vehicle movement, two guides (14, 15) on which the digging chain (4) bears, the two guides being spaced apart from the two surfaces (8a, 8b) and extending on either side of the sleeve-like part (9) of the frame (5).