in fig1 there is shown a front perspective view of one embodiment of aerator apparatus 10 of the invention comprising a generally rectangular frame 12 and one or more cylindrical drums 14 rotatably carried by the frame . attached to the periphery of each drum are a plurality of spike members 20 for perforating the soil as the apparatus is towed across a field . a tongue 18 is shown attached to the forward side 12a of the frame 12 for towing the apparatus with a conventional tractor , for example . attachment points 12b on the rearward side of the apparatus are useful for attaching tongue 18 for towing in the opposite direction , if desired . for example , where the soil is very soft or where there are fragile plants in the soil . preferably there is another tongue member 19 attached to one end of the frame for towing the apparatus on the road , for example , for transport from one field to another . this arrangement enables a very wide implement to be transported on normal roads . in the embodiment shown in fig1 there are wheels 22 positioned at each corner of the frame and are attached by means of casters so that the wheels can turn in any desired direction . it also enables the use of double wheels at each corner without sacrificing maneuverability . the cylindrical drums can be raised or lowered relative to the frame by means of hydraulic cylinders 24 which are connected to the hydraulic system of a towing tractor by means of hoses 25 . all of the hydraulic cylinders operate in unison so that the drums are raised or lowered evenly . when operating the apparatus in soil which is hard and difficult to penetrate , the drums may be lowered completely so that the wheels of the frame are lifted off the ground . this assures that the entire weight of the apparatus is placed on the spikes to urge them into the soil . when operating the apparatus in soil which is looser , the drums may not be lowered completely . rather , a portion of the weight of the apparatus is supported by the wheels . thus , the depth of penetration of the spike members into the soil can be carefully controlled and adjusted . the drums are typically made of heavy steel and are carried on an axle or shaft which extends therethrough . the outer ends of each axle or shaft are carried in holders which are connected to the lower ends of cylinders 24 and which are slidably retained in brackets 23 . this arrangement enables the drums to be raised and lowered by the cylinders very efficiently and smoothly . the spike members are secured at their base ends to band members 26 which are in turn attached to the periphery of drum 14 . preferably there are a plurality of spike members secured to each band member and spaced apart from each other . although not shown in fig1 the band members with attached spike members extend across the full length of each of the drum members . preferably each spike member is bolted securely at its base to the band member , as illustrated in fig2 and 3 . two bolts 27 pass through holes in the base of each spike member to assure that the spike member is very securely held in place . each band member 26 comprises spaced - apart angle iron members 26a and 26b , as illustrated in fig2 and 3 . each spike member is secured between the spaced - apart members 26a and 26b and bolted in place so as to be very secure and very well supported . this imparts great strength and durability to the implement . the band members are capable of being moved axially along the drum 14 so that spacing between adjacent rows of spike members can be easily varied , as desired . this may be easily accomplished because the ends of the band members are bolted together by bolts 28 , as shown . by loosening bolts 28 , the band members are loosened and can then be moved along the drum laterally . then the bands can be tightened again in the new location . depending upon the type of soil being perforated , it may be desirable to move the spike members closer together or further apart . also , additional bands and spikes could be added to the drum , if desired . preferably each band member includes at least two arc - shaped segments or sections which are detachably connected at their ends , e . g ., by bolting the ends together . of course , other means for attaching the band segments or sections together could also be used . the spike members which are useful in the apparatus of this invention preferably have a length of about 12 inches . if the spike members are too short ( i . e ., less than about 6 inches ) they will normally not be able to sufficiently penetrate soil for effective aeration . if the spike members are too long ( i . e ., greater than about 12 inches , no increase in effectiveness is observed . the thickness of the spike member is in the range of about 0 . 5 to 1 inch , with 0 . 75 inch being preferred . the diameter of the drum member is preferably about 3 feet , although it could be as small as about 2 feet or as great as about 4 feet . fig4 is a front perspective view of another embodiment of aerator apparatus 30 of the invention . this embodiment comprises a frame member 32 and one or more cylindrical drum members 34 rotatably carried by the frame . the forward portion of the frame includes attachment brackets 35 for attachment of the apparatus to an existing conventional three - point hitch on a tractor . around the periphery of each drum 34 are a plurality of band members 26 and a plurality of spike members 20 secured to each band member , in the manner described above in connection with the embodiment of fig1 . although only one row of spike members is shown on each drum in fig4 there are a plurality of rows of spike members on each drum . the band members are axially adjustable on the drum in the manner described above . stand members 33 at the corners of the frame are for the purpose of supporting the apparatus when it is not being used . in order to change the depth of penetration of spike members into the soil , the operator of the tractor can adjust the three - point hitch up or down , as desired . fig5 illustrates a preferred embodiment of spike member 20 which is useful in the apparatus . the spike member is arc - shaped and tapered and preferably has a length of about 12 inches . the radius of curvature of the spike member is preferably in the range of about 30 inches , although other curvatures could also be used . the outer three inches or so of the free end of the spike member are preferably hardened to increase wear life . the base includes openings 20a for bolting the spike member to the band members . fig6 shows another embodiment of spike member 40 which is useful in the apparatus . this version is preferably about 12 inches long and is tapered at its outer end , as shown . the base includes openings 40a to facilitate bolting to the band members . this embodiment is not arc - shaped . it is useful when aerating soil which is sandy or very easily penetrated . other variants are possible without departing from the scope of this invention .
apparatus useful for aerating soil , especially grass or hay ground . the apparatus is intended to be towed by a farm tractor , and the apparatus includes elongated spikes on a cylindrical drum . as the apparatus is towed across a field , the spikes penetrate the soil and loosen it as well as providing openings in the soil to improve absorption of water . this reduces water run - off . the spikes are secured to bands encircling the drum , and the spacing between bands is adjustable so that the spacing between spikes can be adjusted .