Rod weeder attachment for an agricultural implement

A tillage attachment device for mounting on an agricultural implement of the type comprising a tool bar, ground wheels for supporting the tool bar for movement across the ground and means for causing the tool bar to move in a direction transverse to its length, the device comprising clamp means for attachment of the device to the tool bar, pivot arm means mounted on said clamp means so as to extend rearwardly therefrom including a first portion extending from said clamp means so as to be pivotal about a horizontal axis at right angles to said arm means and a second rearward portion connected to the first portion at a rearward end thereof so as to extend downwardly therefrom, spring biasing means connected between said clamp means and said first portion of said pivot arm means for biasing said arm means downwardly around said axis, a ground engaging wheel having an axle mounted on said second portion of said arm means remote from said clamp means such that the ground wheel runs on the ground rearwardly of and following said tool bar, said ground wheel having a ground engaging periphery arranged to maintain said axle at a predetermined spacing from the ground, strut means rigidly mounted upon and extending transversely to said first portion of said arm means, two horizontally spaced rigid shank means each rigidly mounted on said strut means and extending downwardly therefrom for engagement with the ground, a rod extending between said shank means at respective lower ends thereof, the position of the rod relative to the ground being controlled by the height of the first portion of the arm means above the ground, bearing means mounting said rod on each of said shank means for rotation relative thereto about a longitudinal axis of said rod, drive means for communicating drive from said ground wheel to said rod for rotating said rod, means mounting the second portion of the arm means on the first portion for free pivotal movement about an axis parallel to said horizontal axis from a first forward position, in which the angle between the first and second positions is a minimum, in which the axle and ground wheel are at a forwardly most extent and in which the length of the shank means relative to the length of the second portion is arranged such that a lowest point of the periphery of the ground wheel is below a horizontal plane containing the rod, to a predetermined second rearward position in which said angle is increased such that the ground wheel is above said horizontal plane by a distance equal to a predetermined required working depth of the rod in the ground, limit means preventing movement of the second portion beyond said second position and means biasing said second portion toward said first position.