a ground working device 1 ( fig1 ) normally designated as a disc harrow comprises a frame 2 in divided form whereon at regular mutual intervals between both parts bearing means 3 are suspended by means of gripping members 23 . pivotally mounted in the bearing means 3 are the first outer ends of standing shafts 4 . the free ends of the standing pivot shafts 4 are provided with lying shafts 5 on which disc - shaped bodies 6 are rotatably mounted . the pivot shafts 4 are arranged on the concave side of each disc - shaped body 6 so that earth thrown up by an adjacent disc - shaped body 6 cannot collect and clog between the pivot shaft 4 and the disc - shaped body 6 . jamming of the disc - shaped body 6 is thus prevented . for adapting of the setting angle of the disc - shaped bodies 6 the disc harrow 1 is provided with setting means 24 . because the disc - shaped bodies 6 are each pivotable relative to the frame 2 the latter does not have to swivel relative to the direction of movement of the tractor 15 . the distance d between the rear wheels of tractor 15 and the device 1 can thereby be minimal and owing to the short - moment arm the working depth of the disc - shaped bodies 6 can be well controlled by the lifting device of an agricultural tractor 15 . fixed to each pivot shaft 4 is a first extremity of a radially extending adjusting body 7 ( fig2 ). the other extremity of the body 7 is provided with a hole which co - acts with an opening 9 arranged in an adjusting member 8 and with detachable pin - like fixation means 10 to attach the adjusting body 7 pivotally to the adjusting member 8 . the outer end of the adjusting member 8 is likewise provided with a number of openings 11 which co - act with an opening arranged in a connecting member 12 joining both frame parts 2 , 2 and second detachable pin - like fixation means 13 to fix the adjusting member 8 in a determined position relative to the frame 2 . the disc harrow 1 further comprises a frame 14 with which the harrow 1 is attached to a three - point lifting device arranged on the rear of tractor 15 . in order to prevent the occurrence of transverse forces and moments around the top axis of the tractor 15 the harrow 1 in the embodiment shown here is of symmetrical construction relative to the centre line of the tractor 15 . to change the setting angle of the disc - shaped bodies 6 the disc harrow 1 is raised by the lifting device so far that the disc - shaped bodies 6 are free of the ground , whereafter the pin - like fixation means 13 connecting an opening 11 and an opening in the connecting member 12 is released , the adjusting member 8 is moved such that the disc - shaped bodies 6 are pivoted by the adjusting bodies 7 in the desired direction and the disc - shaped bodies 6 are fixed in their new position by placing the releasable pin - like fixation means 13 through one of the other openings 11 and the opening in the connecting member 12 . in a second embodiment of the disc harrow 1 according to the invention shown in fig3 the frame 2 comprises a fixed part 25 in addition to two pivotable parts 26 which bear the pivot shafts 4 and are pivotable about a lying axis running substantially transversely of the working direction indicated by the arrow ( fig3 ). the pivotal parts 26 are mounted in bearings 27 attached to the fixed part 25 . the angle of pivot of the pivotable parts 26 relative to the fixed part 25 of frame 2 can be set using setting means 28 , as will be described below . the pivotable parts 26 are mutually connected by adjustable connecting means 29 . each rotating shaft 5 ( fig4 ) of the disc harrow 1 according to the second embodiment of the invention lies at an inclination relative to the ground during working . the disc - shaped body thereby &# 34 ; digs &# 34 ; in the ground whereby the ground is properly churned loose . the optimal value of the angle of inclination &# 34 ; a &# 34 ; enclosed by the rotating shaft 5 and the ground depends on differing conditions , such as type of ground , the crop cultivated and / or to be cultivated thereon and the presence and / or type of any weeds etc . in fig4 angle &# 34 ; a &# 34 ; for clarity is also illustrated between the vertical and a line perpendicular to the rotating shaft 5 . angle values of between 1 ° and 50 ° are however suitable , wherein values of between 20 ° and 30 ° are preferred . in the embodiment shown the angle &# 34 ; a &# 34 ; amounts to roughly 26 °. the angle &# 34 ; a &# 34 ; can be varied by pivoting the pivotable part 26 of frame 2 relative to the fixed part 25 as indicated with dashed lines . the rotating shafts 5 then follows an arced path . each standing pivot shaft 4 is mounted in bearing means 3 which are releasably arranged on the pivotable members 26 and displaceable between different positions located substantially transversely of a working direction at mutual distances on the pivotable member 26 . the shape of the standing pivot shaft 4 is adapted to the curvature of the disc - shaped body 6 such that the distance between the pivot shaft 4 and the disc - shaped body 6 increases in the direction from the center point of the body to its rim . embodying the pivot shaft 4 and the disc - shaped body 6 diverging in this manner prevents any earth adhering to the concave side of the body 6 from collecting at the location of the pivot shaft 4 , whereby the disc - shaped body 6 would still become jammed . the setting angle &# 34 ; b &# 34 ; ( fig5 ) is selected like the angle of inclination &# 34 ; a &# 34 ; in accordance with the type of ground , the sort of cultivated crop and / or type of weed . the figure once again clearly shows the sloping disposition of the disc - shaped body 6 . the latter is arranged in the embodiment shown about a bearing 30 which therefore extends on the convex side of the disc - shaped body . it is however also possible for the bearing 30 to be placed against the disc - shaped body 6 on the concave side , so that the convex side of the body remains substantially smooth ( fig6 ). there is then no danger whatever that the action of the bearing 30 can be affected by the thrown - up earth . the angle of pivot between the pivotable part 26 and the fixed part 25 of the frame 2 is set using adjusting means 28 which are formed by a slot 31 arranged in the fixed part 25 and a bolt 32 movable therein , which bolt is fixedly connected to the pivotable part 26 and provided with a clamping nut 33 ( fig7 ). the pin - hole connection 13 , 11 shown in this figure for adjusting the desired setting angle &# 34 ; b &# 34 ; of the disc - shaped bodies 6 can of course be replaced simply by another setting mechanism , such as a spindle for instance . situations are conceivable where it is desired to select different pivot angles for the two pivotable parts 26 of frame 2 , in order to obtain a varying degree of &# 34 ; digging &# 34 ; action in the two rows of disc - shaped bodies 6 . this may be required because the first row of disc - shaped bodies 6 encounters generally as yet unworked ground while the second row of disc - shaped bodies 6 comes into contact with ground already worked by the first row . in order to enable such variations in the pivot angle the connecting means 29 between the first and second pivotable part 26 are adjustable ( fig3 ). it may be desired to vary the distance in transverse direction between the various disc - shaped bodies 6 . to this end the bearing means 3 in which each standing pivot shaft 4 is mounted can be releasably arranged on the frame ( fig1 ). the bearing means 3 can then be displaced in transverse direction and fixed in particular desired positions by means of pin - hole connections 16 - 18 . by attaching a cultivator 19 to the frame 14 of the first disc harrow 1 in the manner shown in fig8 the working depth of the disc - shaped bodies 6 can be precisely controlled . the position of the cultivator 19 relative to the disc harrow 1 is controlled using ( for instance hydraulic ) adjusting means 20 . when the harrow 1 is lowered by the lifting device fixed to tractor 15 the teeth 21 of the cultivator will dig themselves in and , depending on the position of the adjusting means 20 , pull the disc - shaped bodies 6 of the device 1 to a greater or lesser degree into the ground . thus obtained is a virtually constant working depth . the embodiment of the device 1 shown here comprises a second device 22 according to the invention fixed to the elongation of connecting members 12 , 12 . the addition of a second disc harrow 22 is of importance if the first harrow 1 is provided with disc - shaped bodies 6 which are all positioned in the same direction and which is thus asymmetrical . use of a single disc harrow 1 results namely in such a case in the occurrence of transverse forces and moments making the tractor 15 difficult to control .
a device for working the ground comprising a frame and a plurality of discs is disclosed . each disc is rotatably mounted on a shaft which is provided on one end of a pivotable standing shaft . in order to prevent jamming of the discs by earth thrown up by adjacent discs , each standing shaft is placed on the concave side of its associated disc . the shafts are inclined relative to the ground with this inclination being adjustable . the spacing between adjacent discs is adjustable as is the orientation of the discs .