A height adjuster mechanism (10) for mounting on a frame (11) of a grass and/or ground treatment machine, and connectable to a ground-engaging roller assembly (12) of the machine, in which the mechanism is adjustable in order to vary the height of the frame (11) relative to the roller assembly (12) and thereby adjust the height setting of a grass and/or ground treatment module mounted on the frame (11), and the mechanism comprising: an elongate height adjuster (13) connectable at a lower end (14) to the roller assembly (12), and which is intended to be mounted on the frame (11) to carry out up and down movement lengthwise of its axis in order to adjust the height setting of the treatment module an external thread (15) provided on at least part of the elongate adjuster (13) a rotary adjuster (16) having an internally threaded socket portion (17) rotatably mounted on the external thread (15) of the elongate height adjuster (13), such that rotation of the rotary adjuster (16) can cause lengthwise adjustment of the elongate adjuster (13) an open-topped housing (18) provided on the rotary adjuster (16) and having an upper surface (19) which defines a height adjustment reference datum level an insert (20) mounted on the upper end (23) of the elongate adjuster (13) and which is movable up and down within the open-topped housing (18) as a consequence of lengthwise adjustment of the elongate adjuster (13), and in which the upper surface (21) of the insert (20) can be adjusted to be substantially flush or coplanar with the upper surface (19) of the open-topped housing (18) so as to set a datum level of the treatment module and means for determining the extent of angular adjustment of the rotary adjuster (16) from its position corresponding to the datum level position of the insert (20), so as to set any required height adjustment of the treatment module.La présente invention concerne un mécanisme régleur de hauteur (10) destiné à être monté sur un cadre (11) d’une machine de
