Ladder assembly, rack and engineering machinery

The utility model provides a ladder assembly, a rack and engineering machinery. The ladder assembly is provided with a supporting piece, a ladder, a clamping piece and a connecting plate. One end of the ladder is hinged with the supporting piece, and the other end is provided with a locking part; the clamping piece can be matched with the locking part; one end of the connecting plate is movably connected with the supporting piece, and the other end is movably connected with the ladder; the ladder moves on the supporting piece, so that the clamping piece is matched with the locking part, at the moment, the connecting plate is moved, the clamping piece is matched with the locking part, and the height of the locking part is increased. According to the ladder locking device, the supporting piece serves as a supporting point, the locking part moves along the supporting piece, the clamping piece and the locking part are locked in a matched mode, the connecting plate is arranged, the locking part has a certain posit