referring now to the drawings and , particularly , to fig1 a top plan view of the crop harvesting machine , commonly referred to as a disc mower - conditioner , can be seen . left and right references are used as a matter of convenience and are determined by standing at the rear of the machine facing the forward end , the direction of travel . this disc mower - conditioner 10 is generally comprised of a wheeled frame 12 and a crop harvesting header 20 operatively suspended forwardly thereof . the frame 12 includes a forwardly extending drawbar 14 adapted at the forward end 15 for attachment to a tractor ( not shown ) for movement across the field to harvest crop material . a rotatable drive shaft 16 is housed within the drawbar 14 and is adapted at its forward end 17 for attachment to an external source of rotational power , such as the power takeoff shaft of the aforementioned tractor . the drive shaft 16 powers a primary drive mechanism indicated generally at 18 for drivingly powering the various parts of the disc mower - conditioner 10 described below . further description of the drive mechanism 18 can be found in u . s . pat . no . 4 , 127 , 981 granted to charles a . parrish et al . on dec . 5 , 1978 . the header 20 is defined by opposing side sheets 23 , 24 . the header includes a transversely mounted cutterbar 40 for severing crop material from the ground and a reel 22 , including a plurality of tines 29 , mounted forwardly of the cutterbar 40 for engaging crop material and pulling same rearwardly over the cutterbar 40 . the reel 22 is mounted between opposing left and right side sheets 23 , 24 about a transverse axis of rotation 21 and is rotatably driven by a reel drive mechanism 25 interconnected with the primary drive mechanism 18 . as can be seen in fig1 and 2 , the cutterbar 40 is mounted at a lower portion of the header 20 , transverse to the line of travel and proximate to the ground for severing standing crop material . the cutterbar 40 includes a plurality of rotatable cutter units 42 positioned in a side - by - side relationship . the primary drive mechanism 18 provides rotational power through the cutterbar drive mechanism 45 which through internal gearing 48 , provides rotational power to each individual cutter unit 42 such that adjacent units are rotated in opposite directions . each cutter unit 42 includes at least one cutter blade 49 which is rotatable to sever crop material by impact action . referring now to fig2 a cross sectional view of the disc mower - conditioner 10 , taken through the center of one of the cutter units 42 , can be seen . the header 20 is floatingly suspended from the frame 12 by a header suspension means 13 such that the header can follow the contour of the ground independently of the wheeled frame 12 . a crop conditioning means 30 , mounted in the frame 12 transverse to the direction of travel rearward of the header 20 , is rotatably powered by the primary drive mechanism 18 . as is seen in the preferred embodiment of fig2 the conditioning means 30 includes two transversely mounted conditioning rolls 32 , 33 . the upper roll 32 is mounted above and forward of the lower roll 33 in an intermeshing relationship therewith such that a bite 34 is defined therebetween . the upper roll 32 is biased for movement toward and away from the lower roll 33 by a biasing mechanism 36 . it should be realized by one skilled in the art that crop conditioners other than the particular one shown in fig2 may be utilized . two examples of other crop conditioning means known in the art are non - intermeshing conditioning rolls and the rotating flail - type crop conditioner . the reel 22 is rotatably mounted in an adjustment bracket 38 adjustably affixed to each side sheet 23 , 24 by bolts 39 . by selective manipulation of the position of the adjustment bracket 38 , the reel 22 can be positioned in a plurality of positions as indicated schematically by circular arcs 26 , 27 and 28 . the forwardmost position 28 is generally used when the crop material is lodged close to the ground such that the reel is operative to pick up the downed crop material and pull it rearwardly over the cutterbar 40 . in all positions , the reel 22 is operative to engage crop material and pull it rearwardly over the cutterbar 40 . the position of the tines 29 is controlled by a cam mechanism ( not shown ) such that when the tines 29 have carried the crop material to a position proximate to the bite 34 , the tines 29 are withdrawn perpendicularly to permit an unobstructed flow of the crop material to the crop conditioning means 30 . each cutter unit 42 includes a rotating disc member 41 having at least one cutter blade 49 mounted thereon for rotation therewith to sever standing crop material by impact action . the disc member 41 is rotatable with spindle 47 which , in turn , is driven by the drive gearing 48 and serves as the axis of rotation of each respective cutter unit 42 . since the internal drive gearing 48 is positioned beneath the disc member 41 , this type of cutterbar 40 is commonly referred to as being bottom driven . a further advantage of bottom driven cutterbars 40 is that a stationary ground engaging skid means 46 can be incorporated into each cutter unit 42 . referring now to both fig2 and 3 , a shield 50 , concave relative to the reel 22 and having a center of curvature at the axis of rotation 21 of the reel 22 at the rearwardmost position 26 , is positioned over each cutter unit 42 such that only a portion of the cutter blade 49 extends beyond the forward peripheral edge 52 during rotation of the disc member 41 . when the reel 22 is in its rearwardmost position 26 , the path of travel of the tines 29 is parallel to the concave surface of the shield 50 to provide an efficient mechanism for transferring crop material to the crop conditioning means 30 . the forward peripheral edge 52 is semicircular in shape and is positioned above the forward portion of the circular path of the rotating cutter blade 49 . each shield 50 is detachably affixed to a mounting bracket 57 by a suitable connecting means 54 for convenience in access to the corresponding cutter unit 42 immediately therebeneath . the rearwardmost edge 53 of the shield 50 lies contiguous to a ramp 55 having a planar surface directed upwardly toward the conditioning means 30 . a combination of shield 50 and ramp 55 forming a continuous guide surface 56 for cooperation with the reel 22 to convey severed crop material rearwardly toward the bite 34 of the crop conditioning means 30 . as can be best seen in fig2 guide surface 56 has a low profile configuration conducive to the efficient feeding of crop material , particularly &# 34 ; fines ,&# 34 ; to the crop conditioning means 30 . an alternate configuration and position of the ramp 55 would be curved with a center of curvature at the same location as the shield 50 so as to provide a smooth continuously curved guide surface 56 directed toward the crop conditioning means 30 . as is best seen in fig3 each shield is constructed such that the rearward portion 59 , lying rearward of the connecting means 54 , forms a uniform , transversely planar , uninterrupted surface extending from shield to shield across the entire transverse length of the cutterbar . this shield configuration enables an efficient feeding of the crop material to the conditioning means 30 without the need of a reel 22 having a scalloped tine configuration ; therefore , the reel 22 can utilize tines 29 having a uniform length and still maintain efficient feeding characteristics . in operation , the operator initially positions the reel 22 in accordance with the crop conditions to be encountered . for example , if proper feeding to the crop conditioning means 30 is of primary importance , the operator would position the reel 22 in its rearwardmost position 26 such that the path of the tines 29 is substantially parallel to the guide surface 56 . on the other hand , if the crop is heavily lodged close to the ground , the operator would position the reel 22 in its forwardmost position 28 so that the tines 29 would reach down close to the ground , forward of the rotating cutter blade 49 , to pick up the downed crop material before being severed by the cutterbar 40 . it should be noted that positioning the reel 22 in the forwardmost position 28 does somewhat lessen the efficiency of the reel in feeding crop material to the crop conditioning means 30 since the path of the tines 29 diverges away from the guide surface 56 . generally , the operator will select an intermediate position , corresponding , for example , to circular arc 27 , to balance the desired crop pickup capabilities with the preferred feeding efficiency to the crop conditioning means 30 . after engaging crop material forward of the cutterbar 40 and pulling it rearwardly thereto to be severed by the rotating cutter blades 49 , the reel 22 sweeps crop over the guide surface 56 toward the bite 34 of the crop conditioning means 30 . the guide surface 56 prevents crop from becoming re - engaged with the rotating disc member 41 and its associated cutter blades 49 and , thereby , preventing the cutter units 42 from recutting already severed crop material . the crop conditioning means 30 then conditions the crop material in a known manner before depositing rearwardly thereof on the ground . the shape and configuration of the guide surface 56 is substantially uniform across the transverse length of the header so that a special configuration of the long and short tines on the reel 22 is not necessary for efficient feeding of the crop material to the crop conditioning means 30 . it will be understood that various changes in the details , material , steps and arrangement of parts which have been described and illustrated in order to explain the nature of the invention , will occur to and may be made by those skilled in the art upon a reading of the disclosure within the principles and scope of the invention .
a crop harvesting machine is disclosed wherein a crop engaging reel is mounted forwardly of a disc - type cutterbar so as to pick up downed crop material and to pull it rearwardly over the cutterbar toward a crop conditioner . the cutterbar includes a plurality of bottom driven rotary disc cutter units and an individually removable arcuate shield over each disc cutter unit partially forming a floor to aid the reel in conveying the severed crop material to the crop conditioner and to prevent the cutterbar from recutting the crop once initially severed from the ground . the shields are positioned so that only the cutter blade projects beyond the forward peripheral edge thereof to sever crop material from the ground .