STEPPED PITCH SCREWS
When required, screws of different pitches can be mounted on a common shaft. These may be needed to regulate the feed from a full hopper or to reserve a potion of the conveyor capacity for filling up from a later inlet. It is also used to cut out stagnation of material where the hopper is of the long feeding type.

DOUBLE HANDED SCREWS
Here we have a single shaft on which are mounted screw segments, spirals or paddles or both right and left hand (study diagram carefully). By this means two streams of material may be conveyed simultaneously in opposite directions by single screw or shaft.

TWIN SCREW
Twin screws can be of advantage for sluggish materials. The screws are normally handed and rotate in opposite directions.

REVERSE FLIGHT
.Reverse pitch flight on the discharge end of the screw prevents build up of material at this point and protects bearing and seal.

SHROUDS
Shrouds are used in screw conveyors especially feeders, for reducing the clearance between the screw and the cover plate. They prevent flushing of free flowing materials, and are helpful in maintaining a better regulation of material flow.

INCLINED SCREW CONVEYORS
Inclined screw conveyors operate more efficiently if enclosed in cylindrical casing

TAPERED SCREWS
WITH TAPER TROUGH

VARIABLE PITCH

CONVEYORS FED FROM LONG HOPPERS

Where a screw is used for extracting material from a long hopper a tapered or variable pitch screw is used. If a screw of constant pitch were used the material would be drawn only from the shaded area - the rest stagnating or "staying put". With the tapering or variable pitch screw the entire contents of the hopper are kept actively on the move. Baffles should be fitted into the hopper to relieve the screw of excessive loading.