walls are of a square configuration it is of course understood that various other configurations could be effected also as would be apparent to a worker skilled in the art in a preferred embodiment the length of side portions 29 of the covering panel 19 exceeds the length of the front wall 15 and the rear wall 17 in the preferred embodiment the lower ends of the covering panel extend beyond the lower edges of the front and rear walls to provide extender walls alongside the opened the opened or partially opened bottom wall as can be seen with reference to fig2 so that during the gravitational discharge of materials when the bottom wall 31 of the housing has opened the extended side portions 29 in conjunction with and substantially abutting the opened or partially opened bottom wall reduce the unimpeded entry of outside air into the housing and correspondingly attached tube thus inhibiting diminution of the negative pressure in the loader and in the auger airlock assembly in one alternative embodiment of the present invention at least one of the side portions 29 is formed of a transparent material or alternatively each of the side portions are formed of a transparent material for allowing observation of the discharging material the housing with reference to fig3 further comprises a resilient flap 35 which is connected to a bottom surface of.