referring now to fig1 - 6 of the accompanying drawings , the invention relates to a new and versatile rotary mower assembly of a single , flanged mower arm 2 with two replaceable , twin - edged , bi - functional , dual - tapered , multi - positional knife blades 3 . the knife blades &# 39 ; supporting mower arm 2 has two longitudinal slots 4 which are designed to clear frequently used drive shaft adapter torque assist pins ( not shown ), a popular , large size center pivot hole 5 , and a selection of spacer washer bushings 5a , whose constant outside diameter snugly matches the mower arm &# 39 ; s center hole 5 and whose various concentric bore sizes match the drive shaft adapter &# 39 ; s most common stud and bolt diameters . the mower arm 2 also features two opposing and overlapping flanges 6 and 7 , and alternative flange extensions 6a and 7a , and two pairs of rectangular knife blade suspension hooks 8a , 8b , 8c and 8d provided with threaded screw holes 9 and downwardly faced set screws 10 in their horizontal leg sections . each suspension hook pair 8a and 8b , and 8c and 8d is spaced at an equal distance from the nearest mower arm end . the gate entrances of each suspension hook pair 8 are set in such manner that they face the mower arm &# 39 ; s center pivot hole 5 . each knife blade 3 comprises a flat , level center portion 11 , a leading , downward sloped primary cutting leg section 12 , trailed by an upwardly pitched , sharp edged leg section 13 , and next to it an upwardly sloped leading recutting leg section 14 , trailed by a sharp edged , downwardly pitched leg section 15 . each knife blade has also two pairs of rectangular suspension hook clearance holes 16a and 16b , and 16c and 16d along its centerline , of which each coordinated , outwardly located clearance hole pair 16aand 16c matches and clears the spacing of its correlated mower arm suspension hook pair 8a and 8b , and 8c and 8d respectively . the cutting width is set by adjusting the knife blades 3 with coordinated matching pairs of mower arm suspension hooks . in other words , the knife blades are moved outwardly along the elongated mower arm 2 increasing the cutting width . the cutting width choices are determined by the number of corresponding clearance holes 16a , 16b and 16c , 16d in each set pattern . in adjusting the cutting width , the knife blades 3 are reversed with the first setting as shown in fig1 and 2 with 16a and 16b close to the end of the mower arm 11 , a second setting with 16d and 16c extending from the outer portion of the mower arm 4 , a third setting with 16a and 16b at the outer end of the knife blade 3 extending from the outer portion of the mower arm 4 and a final cutting width extension where 16d and 16c extend at the outer end of the knife blade 3 from the outer portion of the mower arm 4 . the spacing of each knife blade &# 39 ; s pair of clearance holes 16aand 16b , and 16c and 16d is set at two cutting width increments . however , the left hand two hole pairs 16a and 16b , and 16c and 16d are located a single minimum cutting width increment closer to the left knife blade end than the right hand side clearance hole pair 16a and 16b , and 16c and 16d to the right hand knife blade end . this clearance hole arrangement offers four incremental minimum one - inch cutting width settings for each knife blade 3 . the next incremental cutting width increases over the narrowest setting shown in fig1 and 4 requires each knife blade 3 to be reversed end for end prior to engaging its inverted clearance holes 16d and 16b with the left hand mower arm hooks 8a and 8b , and the knife clearance holes 16d and 16b with the right hand mower arm hooks 8c and 8d as shown in fig1 and 4 . for the next larger cutting width setting , both knife blades 3 are again reversed end for end prior to engaging their inverted clearance holes 16b and 16d with the left hand mower arm hooks 8a and 8b , and the knife clearance holes 16b and 16d with the right hand mower arm hooks 8c and 8d . in order to reach the always downwardly facing set screws 10 from below the knife blades &# 39 ; bridge sections 17 engaged in the mower arm &# 39 ; s corresponding suspension hooks 8 are provided with clamping tool access holes 18 which are concentric with , but smaller in diameter than the suspension hooks &# 39 ; threaded screw holes 9 . the set screws 10 are then engaged in these screw holes 9 with their head section facing downward . clamping the knife blades 3 against the tool access holes 18 in the knives &# 39 ; bridge sections 17 is done by turning the set screws 10 counter - clockwise from the mower arm 2 underside . the edges 6b and 7b of the mower arm flange extensions 6a and 7a have the same angularity as each knife blade &# 39 ; s two downward sloped cutting edges 19 . while the invention has been explained by a detailed description of certain specific embodiments , it is understood that various modifications and substitutions can be made in any of them within the scope of the appended claims which are intended also to include equivalents of such embodiments .
a rotary mower includes a flanged , straight rotary mower arm with a plurality of spaced , cutting width related knife blades and suspension hooks . the knife blades are adjustable to various cutting widths and are angular in configuration with respect to the grass being cut . the angular blades are arranged to provide a recutting element to mulch the cut grass in addition to the primary cutting .