referring to the drawings , the threshing apparatus of this invention , indicated generally at 10 in fig1 is shown in assembly relation with a combine 11 having a chassis 12 with front traction wheels 13 and steerable rear wheels 14 . the apparatus 10 is enclosed by a housing member 16 of a generally cylindrical tapered shape . concentrically positioned in a spaced relation within the housing 16 is a tapered rotatable separating cylinder 17 with the space between the housing 16 and separating cylinder 17 defining a clean grain collecting chamber 18 . within the separating cylinder 17 and in a concentrically spaced relation therewith is a threshing unit 19 that is enclosed by a shroud or enclosing housing 21 having an axially extended bottom outlet 22 . the space 23 between the enclosure 21 and the separating cylinder 17 forms a chamber 23 for receiving threshed grain from the threshing unit 19 . the material to be threshed is cut in a usual manner by a cutting mechanism , shown generally at 24 , with the cut material being carried by a conveyor 26 to a feed auger 27 that moves the cut material into the threshing unit 19 . on being threshed , the material enters the receiving chamber 23 and drops onto the rotating separating cylinder 17 for centrifugal separation of the clean grain from the threshed grain material . the clean grain , on passing through the separating cylinder 17 is discharged into the collecting chamber 18 from where it is moved by an auger 28 into a clean grain auger 29 for delivery into a storage bin 31 of the combine from where it is unloaded by an auger 32 . the chaff is discharged from the receiving chamber through an outlet 33 at the rear end of the combine and tailings from the threshing unit 19 are picked up by a tailing auger 36 and returned in a suitable manner to the threshing unit 19 for further threshing action . an operator &# 39 ; s cab 37 having controls for the operation of the combine 11 and threshing apparatus 10 is mounted at the forward end of the chassis 12 . the power source of the combine and theshing apparatus is an engine 38 located adjacent the rear end of the combine . the threshing apparatus 10 includes an elongated open frame structure 39 ( fig1 and 3 ) suitably mounted in a fore and aft direction on the combine chassis 12 and including a pair of longitudinally spaced upright end frames 41 and 42 . each end frame is of a substantially square shape in side elevation with the end frame 41 smaller in size than the end frame 42 and which end frames hereinafter will be referred to as a front upright frame and a rear upright frame , respectively . the frames 41 and 42 are interconnected at opposite corner portions 43 and 44 thereof , respectively , by longitudinal side frame members 46 . the threshing unit 19 is arranged within the confines of the frame structure 39 and includes a shaft 47 extended longitudinally of and through the frame structure 39 for rotatable support in a suitable manner on the combine chassis 12 . supported on the shaft 47 for rotation therewith is a threshing cylinder 48 that has a rub or rasp bar 49 helically wrapped about its outer peripheral surface . operatively associated with the threshing cylinder 48 and mounted on the frame 39 in a concentrically spaced relation about the threshing cylinder 48 is a combination concave and separating grate member 51 comprised of a front concave section 52 and an adjacent rear separating grate section 53 . as shown in fig4 the concave section 52 and separating grate section 53 extend about one hundred and eighty degrees about the periphery of the threshing cylinder 48 and in continuous operative association with the threshing cylinder over the axial length of the threshing unit . the space between the threshing cylinder 48 and the combination member 51 thus defines a threshing zone 54 that has an inlet 56 and an outlet 57 . the separating cylinder 17 is positioned within the dimensional confines of the frame 39 ( fig1 and 4 ) and is rotatably supported on rollers 58 , with a roller 58 being mounted on corner members 60 extended across each corner portion 43 and 44 of the end frames 41 and 42 . the separating cylinder 17 ( fig6 ) is provided with a circumferential guide track 59 for coacting rolling engagement with a corresponding set of rollers 58 on an end frame 41 and 42 . it is seen , therefore , that the receiving chamber 23 is coextensive in axial length with the threshing unit 19 so as to receive threshed grain material from the outlet 22 over the full length of such outlet for action by the separating cylinder . as previously mentioned , the separating cylinder 17 is enclosed within the housing 16 . thus , as shown in fig1 and 4 , the conveying auger 28 is located within an axially extended casing or pocket 65 formed in the lower side of the clean grain collecting chamber 18 and moves grain collected at such lower side into the clean grain auger 29 . to efficiently thresh grain material at a high volume rate , the clean grain must be separated from the threshed material at a rate equal to or greater than the rate at which the cut grain material is supplied to the thresher apparatus . it is thus necessary that the grain separating means be maintained unobstructed and that the chaff and tailings be efficiently removed . since the threshing operation is continuous over the axial length of the threshing unit 16 , it is apparent that the easy to thresh grain will be initially separated and that the threshing operation will proceed progressively along the axial length of the threshing unit to act on the harder to thresh grain . chaff and threshed material is thus introduced into the receiving chamber 23 concurrently with the threshed grain . to continuously remove the chaff and light material from the receiving chamber 23 , the threshing apparatus is provided with a pair of fans 62 and 61 ( fig1 and 3 ) of a blade or squirrel cage type , and arranged in a vertically spaced relation within the housing 16 at positions forwardly of the threshing unit 19 . the fans 63 and 61 supply air under pressure into the forward end of the collecting chamber 18 . as indicated by the arrows 62 in fig1 the air is initially introduced into the collecting chamber 18 and then travels through the perforated separating cylinder 17 for travel axially of the receiving chamber 23 . during such axial flow , chaff and light material is picked up by or entrained in the air for travel therewith outwardly from the receiving chamber 23 for discharge from the machine at the outlet 33 . the perforations 64 in the separating cylinder 17 ( fig2 and 4 ) are continuously maintained open to permit an unobstructed passage therethrough of clean grain by means including a pair of fans 66 and 67 suitably mounted on the frame 39 to opposite sides of the threshing apparatus 10 . each fan 66 and 67 ( fig4 ) extends axially over the full length of the threshing unit 19 and has an outlet 68 terminating in a plurality of discharge nozzles 69 , illustrated in fig4 as arranged in three rows extended axially of and in a spaced relation circumferentially of the separating cylinder 17 . in the operation of the threshing apparatus , the threshed material from the threshing unit 19 on entering the receiving chamber 23 drops onto the inner peripheral surface of the rotating separating cylinder 17 . the grain in the threshed material is moved outwardly of the separating cylinder and through the perforations 64 by the action of centrifugal force . this centrifugal force also tends to hold threshed material against the inner surface of the cylinder 17 so as to interfere with a free passage of grain through the perforations 64 . to agitate and lift such material away from the separating cylinder the nozzles 69 project into the housing 16 and through the collecting chamber 18 for termination adjacent to the outer peripheral surface of the cylinder 17 . high velocity air from the fans 66 and 67 is thus introduced directly at the perforations 64 so that on rotation of the cylinder 17 , the threshed material on the inner surface thereof is continuously lifted and agitated . chaff and light material thus blown inwardly of the receiving chamber 23 is picked up by the air flow supplied by the fans 63 and 61 for discharge at the outlet 33 . to reduce interference with the air blasts from the nozzles 69 , by air currents generated by the rotation of the cylinder 17 , the leading side of each nozzle 69 is provided with what might be called a brush seal 71 having riding contact with the outer periphery of an adjustable outer cylinder 74 associated with the separating cylinder 17 . it will be seen that threshed grain falling into the receiving chamber 23 from the outlet 22 of the threshing zone 54 falls directly onto the rotating separating cylinder 17 for immediate impact and acceleration . since this impact tends to fracture or crack the grain , the outlet 22 is provided with an axially extended impeller 72 rotatable at a speed to move the threshed material from the outlet 22 at a linear speed substantially equal to the peripheral speed of the cylinder 17 . the grain passing through the cylinder perforations 64 and into the collecting chamber 18 is accumulated in the pocket 65 and conveyed by the auger 28 to the clean auger 29 . tailings or heavy heads of grain that travel through the threshing zone 54 are discharged from the threshing zone outlet 57 into the tailing auger 36 for re - entry , in any suitable manner , to the feed auger 27 . as shown in fig1 such material moves downwardly through the air flow produced by the fans 63 and 61 . thus , any chaff or light material within the tailings will be carried away through the discharge outlet 33 . the tapered cylindrical shape of the threshing unit 19 and separating cylinder 17 tends to maintain a free flow of material axially thereof by virtue of the progressively increasing peripheral surfaces of such members . to accommodate the combining of grains of different kinds and size , the separating cylinder 17 ( fig4 and 5 ) is associated with an outer adjustable perforated cylinder 74 formed with perforations 76 of a size and shape and relative spacing corresponding in all respects to the perforations 64 in the cylinder 17 . the cylinder 17 is provided at each end thereof with a radially extended bearing plate 77 ( fig5 ) for rotatably supporting a pinion gear 78 for operative meshing engagement with a gear rack 79 carried at each end of the adjustable cylinder 74 . although only one gear and rack assembly is illustrated in fig4 and 5 , it is to be understood that such assemblies are arranged opposite each other and in axial alignment with the gear 78 being adjustable on rotation of the shaft 81 to move the perforations 76 relative to the perforations 64 between full open and full closed positions therefor . an adjusted position of the cylinder 74 is maintained by the gear assemblies 78 and 79 . it is to be understood that the nozzles 69 extend between the gear tracks 79 . as shown in fig1 the threshing unit 19 and the separating cylinder 17 are operated from the power unit 38 through a gear unit indicated generally at 82 , for operation at relative rotational speeds . it is contemplated that such relative rotation be variable to provide for the most efficient harvesting of the grain material to be threshed . although the invention has been described with respect to a preferred embodiment thereof , it is to be understood that it is not to be so limited since changes and modifications can be made therein which are within the full intended scope of this invention as defined by the appended claims .
a threshing unit is arranged in a concentrically spaced relation within a perforated rotatable grain separating cylinder . an elongated axially fluted impeller located below the threshing unit and within the separating cylinder accelerates the speed of travel of the threshed material to substantially the peripheral speed of the separating cylinder to reduce grain cracking and fracturing . the grain is centrifugally separated through the separating cylinder for removal by a clean grain auger located therebelow and the chaff is discharged by air flowing axially between the threshing unit and the separating cylinder . tailings from the threshing unit are moved rearwardly along the inner peripheral surface of the separating cylinder for pickup and return to the threshing unit . a pair of oppositely arranged axially extended nozzle units direct concentrated blasts of air inwardly of the separating cylinder to lift the chaff and grain from the inner peripheral surface thereof whereby to continuously clean the cylinder perforations for clean grain travel therethrough .