the invention will be described with reference to fig1 , 2 , 3 a , 3 b , 4 , 5 , 6 a , and 6 b wherein like numbers refer to like parts , fig1 shows a rear view of a combine 10 unloading grain to a transport vehicle 12 through a cylindrical shaped unloading tube 14 and a spout 16 . grain is moved from combine 10 through unloading tube 14 by an auger 18 ( see fig3 a and 3b ) in a well known manner . according to the invention , a discharge door 20 sized and shaped to cover discharge outlet 22 , is pivotally attached adjacent discharge outlet 22 , so as to be pivotally movable from a closed position covering discharge outlet 22 to an open position uncovering discharge outlet 22 as shown in fig2 , 3 a , 3 b , and 4 . discharge spout 16 may connect to tube 14 adjacent to discharge outlet 22 accommodating door 20 and its attachment to tube 14 as shown in fig2 . spout 16 may be held in place with one or more hose clamps 26 or the like . in a preferred embodiment of the invention , door 20 is mounted for pivotal movement relative to discharge outlet 22 between a closed position ( fig3 a ) and an open position ( fig3 b ), with a hinge 24 , or the like , and is positively controlled to the closed and open positions . preferred apparatus for positively controlling movements of door 20 include , but are not limited to , an electrically powered actuator 28 as shown in fig2 or fluid controlled actuator 30 as shown in fig3 a and 3b . it is important to note that , because of positive control , door 20 may be opened independent of the presence of grain in tube 14 . that is , the present invention does not require the force of grain acting against the door to effect opening thereof , or the absence of grain to effect closing thereof . as seen in fig2 and 3b , door 20 may be attached on the periphery of unloading tube 14 near discharge outlet 22 , so that opening door 20 may create a separation 21 between door 20 and tube 14 at discharge outlet 22 . as door 20 closes , grain that may remain on door 20 will discharge through spout 16 or be carried back into tube 14 . because no ledge is created by a connection point between door 20 and tube 14 near discharge outlet 22 , it is unlikely that grain will lodge in separation 21 to inhibit the closing of door 20 . when door 20 is in the closed position , it is positively held in that position by actuator 28 30 as shown in fig2 and 3a , and substantially covers discharge outlet 22 virtually eliminating the possibility of grain dribble or slosh from tube 14 . when positively controlled to be in its open position , as shown in fig3 b , door 20 uncovers discharge outlet 22 and is positioned outside of a discharging stream of grain 25 along a flow path 31 . also , when door 20 is positively held in its open position , the force created when auger 18 moves grain through unloading tube 14 is not required in any way to open door 20 and therefore is not dissipated by pushing and holding open a spring biased door , as is required in the prior art discussed above . as a result , the grain is allowed to flow unopposed , as if no door was present , such that it is discharged in a cohesive , predictable stream 25 along flow path 31 . although shown attached to tube 14 near outlet 22 , it is contemplated according to the invention that door 20 could alternatively be mounted within spout 16 and perform in essentially the same manner . another aspect of the invention related to discharge outlet 22 can be seen in fig2 . a circumferential edge bounding discharge outlet 22 may be slanted diagonally so that an upper portion 27 of unloading tube 14 extends longitudinally outwardly of a lower portion 29 of tube 14 . this arrangement may facilitate attachment of door 20 in the above described manner . in addition , as illustrated in fig1 , this arrangement may extend the reach of unloading tube 14 by a distance 49 as upper portion 27 extends further into spout 16 than lower portion 29 . another feature of the invention that reduces obstruction to grain flow can be seen in a simplified schematic top view of the unloading tube 14 as shown in fig5 . helical auger 18 includes a helical flight 40 having an auger surface 41 extending around an auger shaft 42 which is supported adjacent to discharge outlet 22 for rotation by a bearing ( not shown ) about a central longitudinal axis 43 . the bearing is supported by at least one strut 32 , 34 , 36 having a thinnest sectional extent 44 in a direction substantially parallel to auger surface 41 , which is parallel to the grain flow as shown in fig5 and 6b for reducing division of grain stream 25 . this effect can be understood with reference to fig6 a and 6b . fig6 a shows a typical prior art attaching member 32 a situated parallel to longitudinal axis 43 of auger shaft 42 . when grain is urged forward by auger surface 41 , it approaches a prior art strut 32 a at an angle . discharging grain impacts sectional extents 44 and 46 of strut 32 a causing a separation 50 in grain stream 25 which is relatively wide . fig6 b shows strut 32 of the present invention situated so that only its thinnest extent 44 is parallel to auger surface 41 . in this case , when the grain is urged forward by auger surface 41 , strut 32 is generally parallel to grain stream 25 minimizing separation to no more that extent 44 which is smaller than separation 50 . notice also in fig6 b , that strut 32 may be narrowed at a leading end 48 to gradually interrupt the discharging grain , possibly resulting in even less separation in grain stream 25 . struts 34 , 36 may also be aligned with grain stream 25 in a similar manner . thus when grain discharges past at least one strut 32 , 34 , 36 , attached in an orientation so as to reduce separation , through discharge outlet 22 without resistance or interference from positively controlled door 20 , discharge grain stream 25 may be tighter , stronger and less susceptible to loss due to wind . referring to fig2 , 3 b and 4 , it should be noted that the bottom region of spout 16 can be shaped to accommodate and receive door 20 when in the open position so as to be located beneath flow path 31 , and will have a suitable opening for passage of actuator 28 , 30 to door 20 . another advantage of this arrangement , at times when only a minimal amount of grain is being discharged and fall onto door 20 , it will be allowed to smoothly transition onto the bottom outer surface of spout 16 and easily exit . it will be understood that changes in the details , materials , steps , and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention . the foregoing description illustrates the preferred embodiment of the invention ; however , concepts , as based upon the description , may be employed in other embodiments without departing from the scope of the invention . accordingly , the following claims are intended to protect the invention broadly as well as in the specific form shown .