Abstract: A plough assembly of the kind which during use is raised and lowered relative to a surface to be ploughed or cleared: is provided having a wing with a forwardly facing surface and a lower edge; a steel share carried by the wing adjacent the lower edge thereof, the steel share having a lower scraping edge permanently disposed below the lower edge of the wing; a mud share pivotally connected to the wing for swinging movement about a generally horizontal axis between an operative position in which the mud share rests against the steel share and at least a portion of the mud share is disposed below the lower edge of the steel share and an inoperative position in which the mud share is disposed above and rearwardly of the lower edge of the steel share; a hydraulic piston and cylinder device for swinging the mud share between the operative and inoperative position and for retaining the mud share in its operative position, the device being hydraulically connected to an overflow valve which is adjustable to a predete