belt upper flight 14 a as can be seen in fig4 the width of trough 46 between upper legs 46 a and 46 b is less than the width of belts 12 and 14 which may be seen in their respective return flights 12 b and 14 b above and below trough 46 as additional product is added between the belts the upper belt lower flight is raised thereby further increasing the curvature and pressure of the upper belt against the product lower portions 46 c and 46 d of the legs of trough 46 have lower ends which slope inwardly and are connected to horizontal base 46 e of trough 46 it can be seen that the slope of the lower end of leg lower portions 46 c and 46 d also supports the curvature of lower belt upper flight 14 a as it slides along trough 46 the upper ends of trough leg upper portions 46 a and 46 b are connected to the tube side walls 44 c and 44 d respectively by coplanar shelves 48 shelves 48 will retain the return flight 12 b of upper belt 12 on its return from the discharge end of conveyor hopper 16 a space between trough 46 and tube bottom wall 44 b will receive the return flight 14 b of lower belt 14 referring now to fig5 a second embodiment of the.