The drive unit comprises of an electrical motor, gear box and couplings. Material is fed through the feed hopper fixed on the trough cover. A umber of discharge sprouts with rack gears for closing and opening as required, are provid crew conveyors are generally operated horizontally or at a small inclination (10° to 20°). However there are special designs whe the load is moved vertically up or at a small angle to vertical. These are called vertical screw conveyors. 6.7.3 Aspects of Screw Conveyor Design (a) Recommended Dimension of a Screw Conveyor: The dimensions of principal c of a screw conveyor are nominal diameter of the helical pitch of the diameter of screw, screw, screw shaft, width of trough determining the gap between trough and screw, trough height from center of screw shaft, thickness of trough material and nominal thickness of screw flights. Indian standard specification IS:5563:1985 has specified the standard dimensions for all above components. The recommended dimensions as per above is is given in Table 6.7.1.The nota- tions used in the table are shown in Fig. 6.7.3.