46 the lower portion 25 extends through bottom plate 47 and with middle portion 23 they form a smooth continuous slot through support member 2 as indicated at 99 in fig3 the transition from opening 21 to slot 81 may be made by a diagonal wall with fillets 100 and radii 101 to avoid sharp intersections which may cause stress concentration and to improve casting opening 21 has inclined surfaces 22 and 26 at its top and bottom respectively to allow rocking of the drawbar about a horizontal axis surface 22 is inclined upwardly from the central axis 98 of drawbar 1 and support casting 2 surface 26 is inclined downwardly from central axis 98 complementary inclined surfaces 28 29 may be provided at the bottom and top respectively of the inner end 12 of drawbar 1 also to permit such rocking support casting 2 has aligned bores 27 and 45 extending through bottom plate 47 and top plate 46 respectively into which bores are inserted bushings 7 which in turn receive pin 5 bushings 7 are preferably of a hard wear resistant material and preferably are press fitted into bores 27 and 45 pin 5 is held in its vertical position within the support casting by pin support plate 9 nuts 13 and bolts 14 the width of slot 81 is at least slightly greater than the width of wedge 4 so that the wedge can move vertically as needed without binding follower 3 is made so that it also has side clearance in slot 81 follower support plate 8 serves to maintain follower 3 in its proper vertical position follower support plate.