referring now to fig1 , a disc harrow 10 has a mainframe 12 defined by a pair of rails 14 connected to one another by a series of transverse supports 16 spaced from one another along the length of the rails 14 . the disc harrow 10 is designed to be towed by a tractor or other powered device . in this regard , the disc harrow 10 includes a hitch 18 for connecting the mainframe 12 to the tractor . in the illustrated embodiment , the disc harrow 10 includes a pair of disc gangs 20 , 21 mounted to the mainframe 12 using a subframe 22 , which will be described in greater detail below . the pair of disc gangs includes a forward disc gang , designated by numeral 20 , and a rearward disc gang , designated by numeral 21 . the disc gangs 20 , 21 are connected to one another by an i - beam 24 and a pair of gang braces 26 , only one of which is visible in the figure . each disc gang 20 , 21 has a series of reels or discs 28 each of which is mounted to a disc support beam 30 , 31 , respectively , by a clamping device 32 . in the illustrated example , each disc support beam 30 , 31 has a pair of support arms 30 a , 30 b and 31 a , 31 b , respectively . the support arms are angled relative to one another in such a manner that disc support beam 30 is generally v - shaped whereas disc support beam 31 has a generally inverted v shape . collectively , the pair of disc support beams 30 , 31 when connected together by i - beam 24 have a generally h - shape . each clamping device 32 includes a clamp 34 fastened to a clamp plate 36 having a downwardly extending arm 38 that connects to the hub 40 of each reel 28 . with additional reference to fig2 , the subframe 22 has a forward pipe 42 and a rearward pipe 43 spaced from one another and coupled to respective transverse supports 16 using suitable connectors . the rearward pipe 43 is coupled to a cross brace 44 secured to the disc support beam 31 of the rearward disc gang 21 . cross brace 44 , using a suitable connection , is coupled to each support arm 31 a , 31 b . pipe 43 and cross brace 44 are coupled to one another with a bracket and hinge arrangement 46 that allows the height of the rearward disc support beam 31 , and thus the rearward disc gang 21 , to be adjusted . more particularly , rearward pipe 43 mechanically communicates with forward pipe 42 via piston 48 that is coupled to forward pipe 42 . a bracket and hinge arrangement 50 is used to couple the forward pipe 42 to i - beam 24 . the piston 48 is also connected to an actuator 52 via a lever 54 that is rotatable about forward pipe 42 . in this regard , the actuator 52 may be energized to pull lever 54 forward to lower the forward disc gang 20 and the rearward disc gang 21 or push lever 54 rearward to raise the forward disc gang 20 and the rearward disc gang 21 . when lowering the disc gangs 20 , 21 , the actuator 52 is activated so that lever 54 pushes piston 48 rearward , which causes lever 56 coupled to rearward pipe 43 to rotate downward , thereby resulting in the rearward disc gang 21 being lowered in concert with the forward disc gang 20 . when raising the disc gangs 20 , 21 , the actuator 52 is activated so that lever 54 pulls piston 48 forward , which causes lever 56 coupled to rearward pipe 43 to rotate upward , thereby resulting in the rearward disc gang 21 being raised in concert with the forward disc gang 20 . this construction allows the disc gangs 20 , 21 to be positioned at an infinite number of heights defined between the rotational limits of levers 54 , 56 . the subframe 22 also includes a pair of lateral supports 58 , one of which is bracketed to pipe 42 and the other of which is coupled to a pivoting mechanism 60 . as further illustrated in fig3 , pivoting mechanism 60 includes a cushion 62 , having a curved shape , coupled to a respective lateral support 58 . the cushion 62 is coupled to a pipe , which in the illustrated example is forward pipe 42 , by a bracket 64 . bracket 64 includes a pin 66 about which cushion 62 is secured by a clamp 68 . this coupling allows the cushion 62 to rotate or otherwise pivot relative to bracket 64 when the disc gang 20 encounters an obstruction . the cushion 62 presents a spring load on lateral support 58 which is coupled to the disc gangs 20 , 21 by brace 26 . during unobstructed passage of the disc gangs 20 , 21 , the spring load maintains the depth of the disc gangs 20 , 21 at a relatively constant level . when an obstruction is encountered , cushion 62 will deflect thereby absorbing the force imparted by the obstruction . when the force of impact exceeds the bias of the cushion 62 , the cushion 62 will rotate about pin 66 thereby drawing the disc gangs 20 , 21 upward relative to the mainframe 12 , as shown in fig4 . in this regard , cushion 62 is designed to provide a two - stage response to impact with a larger obstruction . in the first stage , the cushion 62 deflects . in the second stage , the cushion 62 will draw the disc gangs 20 , 21 upward relative to the mainframe 12 thereby drawings the disc gangs 20 , 21 over and thereby clearing the obstruction . when the bias of the obstruction removed , i . e ., the obstruction has been cleared , the spring bias of the cushion 62 is restored , the cushion rotates downwardly relative to pin 66 , as shown in fig5 , and returns the disc gangs 20 , 21 to their normal working depth . it is recognized that the disc harrow 10 may have one or more pivoting mechanisms to assist with obstruction clearing . for example , a pivoting mechanism could be coupled to each of the support beam arms . in another example , when at least two pivoting mechanisms 60 are used , mounted on opposite sides of the subframe 22 , the subframe 22 and thus the disc gangs 20 , 21 may be caused to oscillate when an obstruction is encountered . more particularly , fig6 shows a front elevation view of a portion of the disc harrow 10 during normal working operation . when an obstruction is encountered of sufficient size to overcome the bias of the cushion of either pivoting mechanism , the disc gangs 20 , 21 will oscillate . thus , the disc gangs will be allowed to move side to side and front to rear when an obstruction of sufficient size is encountered , as illustrated in fig7 . the present invention has been described with respect to a disc harrow , but is understood that the present invention is equivalently applicable with other soil tilling implements . moreover , the invention may be applicable for a stand - alone disc harrow or a farm implement carrying multiple types of soil tillage tools . for example , cultivating tines may be coupled to the transverse supports 16 . additionally , it is contemplated that the reels 28 of the disc gangs 20 , 21 may be of similar size or of dissimilar size . for example , the forward disc gang 20 may have large reels for primary tillage whereas the rearward disc gang 21 may have smaller reels for secondary tillage . many changes and will modifications could be made to the invention without departing from the spirit thereof . the scope of these changes will become apparent from the appended claims .
a disc harrow composed of one or more disc gangs has a subframe coupled to the disc gangs to move the disc gangs in response to variations in farmland terrain to limit the impact of obstructions when encountered during the harrowing process . when the obstruction is cleared , the subframe automatically returns the disc gangs to their pre - obstruction position . in addition to reducing the potentially - damaging impact of obstructions , the subframe also maintains a more consistent reel depth during undulations or changes in the farmland terrain , such as during harrowing of slopes or unleveled fields such as valleys , near waterways , and along fence rows .