referring to the drawing , it may be seen that the unit is adapted to be attached to tool bar 10 . the tool bar is horizontal and is mounted on an agricultural draft vehicle in the form of a tractor . the direction of draft is indicated by arrow d . a plurality of rotary hoes 12 is attached to the tool bar 10 by mechanism to be described later . it will be understood that each rotary hoe includes an axle 14 . hub 16 journalled to the axle . a plurality of tines 18 radiate from the hub in a plane to form the diameter of the rotary hoe . those skilled in the agricultural art will understand rotary hoes , as described above , are old and well known in the art and commercially available . clamp 20 is attached to the tool bar 10 and horizontally adjustable along the length of the tool bar and is clamped securely in place by tool bar bolt 22 . bar shank 24 is clamped in a vertically adjustable position by shank bolts 26 . i . e ., the desired position of the bar shank is determined and then upon tightening the bolts 26 , the shank 24 will be in the vertical position desired . sleeve 28 is pivoted to the bottom of the bar shank by sleeve pivot 30 . the sleeve has two ears projecting up from it , one of which has been broken away in fig3 for clarity , so that it may be seen that the sleeve 28 is free to rotate about an extremely large angle about the sleeve pin 30 . the axis of the sleeve pin 30 is parallel to the horizontal tool bar 10 . horizontal bar 32 is telescoped within the sleeve 28 . the horizontal bar 32 is aligned with the direction of draft d . the horizontal bar is set in place by set means in the form of set screw 34 extending through the sleeve 28 and bearing against the horizontal bar 32 . spring bracket 36 telescopes over the top of the bar shank 24 and is held in position by a set screw extending through the bracket . the rear of the bracket 36 is bifurcated ( a portion of which is broken away in fig3 ) so that cross sleeve 38 may be mounted therein . rod 40 telescopes through the cross sleeve 38 and has hook in the bottom portion which extends through ears 42 on the back of the horizontal bar 32 . helical compression spring 44 telescopes around the rod 40 and bears against the cross sleeve 38 and the ears 42 . thus , it may be seen that the helical compression spring will bias the rear of the horizontal bar downward . the downward movement of the horizontal bar is limited by stop 48 attached to the rod 40 above the cross sleeve 38 . spring means , as described , are common to the agricultural arts . hoe shank 50 is rigidly attached , as by welding , to the back of the horizontal bar 32 . central carriage 52 has two ears 54 which extend upward therefrom . two bolt holes extend through the ears 54 . a carriage pivot pin 56 extends through the lower of the two holes and also through a hole in the bottom of the hoe shank 50 . therefore , the central carriage 52 is pivoted to the bottom of the hoe shank . however , the swing of the carriage about the pin 56 is limited by the fact that the edges of the hoe shank 50 extend down so that they strike portions of the central carriage 52 . fig3 shows the maximum amount of rock or tilt or swing the central carriage can have relative to the hoe shank 50 . at the maximum tilt the tines 18 will clear the front of the horizontal bar 32 . a second hole in the ears 54 is aligned with another hole in the hoe shank 50 and a bolt may be placed through these holes if it is desired to lock the central carriage in one position upon the hoe shank . when the unit is to be used as a rolling shield , it might be desired to lock the carriage to the shank as described . the central carriage 52 includes forward stub arm 58 which extends forward of the central carriage . rear stub arm 60 extends to the rear of the central carriage . forward arm 62 is bolted to the stub arm 58 . it will be noted that carriage bolts with round heads are used on the stub arm side so that there is no protrusion adjacent to the tines 18 of the forward most rotary hoe 12 . likewise , rear arm 64 is bolted to the rear stub arm 60 with carriage bolts as described . forward axle bolt 66 extends through the forward end of the forward arm 62 . one of the axles 14 is on one end thereof and the other end is bolted to the forward arm . thus it may be seen that the axle is cantilevered from the forward arm and supported only on one side of the forward arm . also it will be noted that the forward arm 62 is bent so that the spacing between the rotary hoes is equal as described previously and particularly seen in fig4 . likewise , rear axle bolt 68 extends through the end of the rear arm 64 ( which is also bent ) and one end of the rear axle bolt forms one of the axles 14 and the other end is bolted to the rear arm 64 . central axle bolt 70 has one of the axles 14 on each end thereof and it extends through the central carriage 52 in line and halfway between the forward axle bolt 66 and rear axle bolt 68 . it may be seen also that the rotary hoes , which are mounted on the central axle bolt , are cantilevered out from the central carriage and supported on only one side . it may be seen that the distance of the front axle bolt 66 to the central axle bolt 70 is the same as the distance from the rear axle bolt 68 to the central axle bolt 70 and that each of these distances is less than the diameter of each of the rotary hoes 12 ; all of the rotary hoes 12 having the same diameter . also , it may be seen from the drawings that the plane of the tines of each of the four hoes is spaced an equal amount from the plane of the next nearest hoe . therefore , it may be seen that i have achieved the desired results identified above of having the tines of the rotary hoe overlapping so that they can be self cleaning yet have a minimum of any other obstructions such as framework , or the like to form an obstruction of trash which might accumulate on the times of the rotary hoes . with the forward and rear arms 62 and 64 removed , the two hoes on the central axle bolts may be used as shields for sweeps attached to the tool bar 10 . the horizontal bar 32 may be moved until the hoes are properly related to the sweeps . as an aid to correlating the terms of the claims to the exemplary drawing , the following catalog of elements is provided : ______________________________________10 tool bar 42 ears12 rotary hoes 44 spring14 axle 46 stop16 hub 48 stop18 tines 50 hoe shank20 clamp 52 central carriage22 tool bar bolt 54 ears24 bar shank 56 carriage pivot pin26 shank bolts 58 forward stub arm28 sleeve 60 rear stub arm30 sleeve pin 62 forward arm32 horizontal bar 64 rear arm34 set screw 66 forward axle bolt36 spring bracket 68 rear axle bolt38 cross sleeve 70 central axle bolt40 rod______________________________________ the axles 14 are desirably close together . the front and rear hoe could be closer to the central axle bolt 70 than is shown in the drawing . there must be clearance between the tips of the tines 16 and the axle bolt 70 . the embodiment shown and described above is only exemplary . i do not claim to have invented all the parts , elements or steps described . various modifications can be made in the construction , material , arrangement , and operation , and still be within the scope of my invention . the limits of the invention and the bounds of the patent protection are measured by and defined in the following claims . the restrictive description and drawing of the specific example above do not point out what an infringement of this patent would be , but are to enable the reader to make and use the invention .
a set of four rotary hoes are evenly spaced apart laterally so that the distance between the tracks is two inches and the distance between the outside hoes is six inches . the assembly is pivoted about the center to ride over uneven ground . the front and back hoe are removable so that the other two hoes , which are widest apart , may be operated as a rotating shield . the mounting is attached to the tool bar of a tractor and spring biased downward .