throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art . however , well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure . accordingly , the description and drawings are to be regarded in an illustrative , rather than a restrictive , sense . embodiments of this invention provide a front - mounted tilling assembly that may be used in conjunction with a plough . the tilling assembly can be controlled to till the soil that was ploughed on a previous pass of the tractor . the tilling assembly can be used most effectively in combination with a tumble plough . fig1 is a top - view of a tractor 10 pulling a tumble plough 12 . a tilling apparatus 15 is mounted on the front of the tractor 10 . tilling apparatus 15 comprises arms 16 r and 16 l arranged to project respectively on the right and left - hand sides of tilling apparatus 15 . arms 16 r and 16 l each comprise tilling members . in the illustrated embodiment , the tilling members comprise disc blades 18 . the tilling members may optionally comprise other blades or tines in addition to or in the alternative to disc blades . disc blades 18 are mounted to shafts 19 ( see fig5 ) which are rotatably mounted to the corresponding arm 16 r or 16 l . arms 16 r and 16 l can be lowered so that the corresponding disc blades 18 are in contact with and till the soil or raised so that the arm 16 r or 16 l is not in contact with the soil . fig2 a is a top - view of a tractor 10 commencing to plough a field . the tractor will follow path 20 to allow plough 12 to cover the entire area of the field . in fig2 a , the tractor has commenced ploughing . the plough shares on plough 12 are turning over the soil towards the right - hand side of the tractor as indicated by arrows 22 . arms 16 r and 16 l are in their raised positions with disc blades 18 out of contact with the ground . the weight of arms 16 r and 16 l on the front end of tractor 10 provides front ballast that assists in maintaining traction ( in the event that tractor 10 has driven front wheels 11 ). in fig2 b , tractor 10 has completed its first pass along the field and has turned around , flipped tumble plough 12 and started to proceed in the opposite direction . it can be seen that the tumble plough 12 is now ploughing so that soil is turned over toward the left - hand side of tractor 10 as indicated by arrows 24 . arm 16 l has been lowered so that its tilling members ( disc blades 18 ) are tilling the soil that was ploughed on the previous pass . arm 16 r remains in its raised position . fig2 c shows the field with the tractor on the next pass . the tumble plough 12 has been flipped again and is now ploughing so that soil is turned over towards the right - hand side of tractor 10 . arm 16 r has been lowered to bring the corresponding tilling members ( e . g . disc blades 18 ) into engagement with the ground ploughed on the previous pass . arm 16 l has been raised . the tilling members ( disc blades 18 ) on the lowered arm 16 r are tilling the soil turned over in the previous pass of plough 12 . by proceeding as described above , a farmer can both plough and till a field with a single pass over the field . furthermore , since the tilling apparatus may comprise or be used in conjunction with a tumble plow , tractor 10 does not need to travel for any significant distances to transport plough 12 to a new starting point . tractor 10 can cover the entire field by making u - turns to change direction when it reaches the ends of the field . as illustrated in fig2 b and 2c , the lengths of arms 16 and the portions of those arms which carry tilling members 18 are selected to facilitate tilling of the soil that has been turned over in an adjacent previous pass of plough 12 . the portion 25 ( see fig4 ) of arms 16 which carry tilling members ( e . g . disc blades 18 ) may be at least approximately the same length as the width covered in each pass of plough 12 . in some embodiments , portion 25 is slightly longer than the width of each pass of plough 12 to provide some overlap between the strips tilled in successive passes of tilling apparatus 15 . although farmers like to do a neat job of field preparation , ploughing does not require high precision . portion 25 is offset from a centerline of tractor 10 to coincide with an adjacent strip of land that has been ploughed in a previous pass of plough 12 . portions 25 may be offset by the same amount respectively to left and right sides of the tractor centerline . in the illustrated embodiment , when the corresponding frame 33 r or 33 l is in its lowered configuration , the corresponding portion 25 does not extend significantly into the current path of plough 12 . the tilling members of tilling apparatus 15 are arranged so as to leave a gap between the strips that can be tilled by portions 25 . in the gap there are no tilling members ( or in the alternative any tilling members that may be present for other applications are mounted by a retraction mechanism that may be operated to keep such tilling members retracted away from the ground to allow for operation of tilling apparatus 15 as described herein ). in the illustrated embodiment , tilling members of either one of portions 25 may be engaged with the ground to till the soil without bringing any tilling members into engagement with the ground in a strip extending more - or - less the width of plough 12 . this allows plough 12 to work on clean , un - cut soil . apparatus 15 may be configured such that , with plough 12 configured to plough to one side , when the arm 16 r , 16 l corresponding to that ploughing direction is in its lowered configuration , the corresponding portion 25 may have its innermost edges in line with or nearly in line with the edge of the strip being currently ploughed by plough 12 and extend outwardly ( away from the centreline of tractor 10 ) from that point . in the illustrated embodiment , when a frame 33 r or 33 l is in its lowered position , the corresponding portion 25 begins approximately even with the outside edges of tires 11 of tractor 10 . leaving at least part of the track of tires 11 untilled is advantageous since the soil on which tires 11 drive can remain undisturbed by tilling apparatus 15 , thereby maintaining traction . advantageously , apparatus 15 may be configured such that , when a right arm 16 r is in its lowered configuration , the corresponding tilling members are positioned to engage the ground in a first strip that is offset to the right side of tractor 10 and when left arm 16 l is in its lowered configuration , the corresponding tilling members are positioned to engage the ground in a second strip that is offset to the left side of the tractor and the first and second strips are spaced apart from one another by a third strip . advantageously the third strip may extend into the track of tires 11 past the inner edges of tires 11 . in some embodiments , the track of tires 11 may be entirely within the third strip . depending upon its width , plough 12 may plough a strip that substantially lies within the third strip . fig3 through 10c show some details of construction of an example embodiment of tilling apparatus 15 . in the illustrated embodiment , arms 16 r and 16 l respectively comprise frames 33 r and 33 l . apparatus 15 comprises a central frame 30 which includes a coupling 32 for mounting to the front of a tractor 10 . in some example embodiments , coupling 32 comprises a 3 - point hitch coupling that couples to a front - mounted 3 - point hitch assembly on the front end of tractor 10 . in alternative embodiments , frame 30 could be bolted or otherwise affixed to the front of tractor 10 . swinging frames 33 r and 33 l are pivotally attached to central frame 30 . a disc assembly 34 is attached to each of swinging frames 33 r and 33 l . disc assembly 34 comprises a member 36 to which is rotatably mounted a shaft 19 which carries disc blades 18 . actuators ( for example hydraulic cylinders ) are coupled between mounting points on central frame 30 and corresponding mounting points on swinging frames 33 r and 33 l . the illustrated embodiment includes hydraulic cylinders 40 r and 40 l which are respectively coupled to raise and lower swinging frame 33 r and swinging frame 33 l . in a simple embodiment , hydraulic cylinders 40 r and 40 l are controlled by means of auxiliary hydraulic circuits ( not shown ) of a tractor 10 . control levers for controlling each of these auxiliary hydraulic circuits may be provided in a cab of tractor 10 . by operating the control levers , a driver of the tractor can individually control each of swinging frames 33 r and 33 l to move between its raised and lowered positions and to stay in the selected raised or lowered position . some embodiments provide a more automatic control . in such embodiments , a single control lever or other user interface may be provided which has positions or commands for left frame 33 l down ( and right frame 33 r up ); right frame 33 r down ( and left frame 33 l up ); and transport position ( both right and left frames 33 l , 33 r up ). members 36 may be angled relative to the direction of travel of tractor 10 to provide a desired tilling action . as illustrated in fig1 a to 10c , some embodiments permit the angles of members 36 to be varied to modify tilling action of disc blades 18 . since only one of left and right arms 16 l and 16 r is being deployed at a time in normal operation , an alternative embodiment as shown in fig1 has only a single arm that can be swung between left and right sides of a tractor 10 . in the fig1 embodiment , single arm 50 carries first and second sets 51 l and 51 r of tilling members . arm 50 can be carried in a central upright position for transport . additionally , arm 50 can be swung to the left to bring tilling members 51 l into contact with soil on the left - hand side of tractor 10 . arm 50 can be swung to the right to bring tilling members 51 r into contact with the soil on the right - hand side of the tractor . any suitable actuator may be applied to swing arm 50 between its positions and to hold arm 50 in a position after that position has been selected . for example , the actuator could comprise a hydraulic motor , a rack and pinion mechanism , a hydraulic piston , or the like . other constructions are also possible . for example , front - mounted tilling members on either side of a tractor 10 may be mounted so that they can be independently lifted away from engagement with the soil or lowered to engage and till the soil by means of a mechanism which lifts and lowers the members in a generally vertical direction . alternative types of tilling members may be provided . for example , motor - driven rotary tiller blades may be mounted in place of disc blades 18 . such blades may be driven , for example , by means of a hydraulic motor connected to be driven by pressurized hydraulic fluid supplied from tractor 10 . movable or fixed , driven or non - driven tines may be provided instead of or in addition to disc blades 18 . instead of being mounted on the front of a tractor 10 , arms 16 r and 16 l could be mounted to sides of tractor 10 so that they can be lowered to bring tilling members into position to till a previously - ploughed strip of soil . while it is most efficient to use an implement as described herein together with a tumble plough , some embodiments comprise a single - bottom plough . such embodiments require only a single arm that can be lowered to bring tilling members into contact with a strip of land ploughed in a previous pass . the single arm may be mounted on the side of the tractor toward which the plough turns the soil . preferably the tilling members are mounted so that , when they engage the ground at least inside edges of tires of the tractor 10 drive on ground that has not been tilled by the tilling members . for example , the tilling members may be mounted so that they till a strip of land beginning just outside of the tractor &# 39 ; s front wheels and extending outward ( away from the centerline of the tractor ) for the width of the plough being pulled by the tractor or slightly farther . although tractor 10 is depicted as having tires , the invention may be applied using a tractor having tracks . tractor 10 is not required to be a purpose - built agricultural tractor but may be a crawler tractor or any other vehicle capable of application as described herein . while a number of exemplary aspects and embodiments have been discussed above , those of skill in the art will recognize certain modifications , permutations , additions and sub - combinations thereof . it is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications , permutations , additions and sub - combinations as are within their true spirit and scope .
a method of soil preparation simultaneously ploughs soil and tills soil ploughed in a previous pass . an apparatus for tilling soil provides tilling members mounted for deployment on either side of a tractor . the tilling members on one side of the tractor may be brought into engagement with the soil while tilling members on the other side of the tractor are lifted away from the soil . the tilling members are located to coincide with an adjacent strip of land ploughed in a previous pass of the tractor .