Special designs/features
A number of features can be incorporated in an unpowered conveyor to satisfy different functional requirements. Some of these are described below.
(i) Double-row roller conveyor: This design is used to convey wide and heavy loads. In
place of one long and proportionately large diameter roller, two smaller diameter rollers with lengths less than half of the larger roller are used. To support the inner ends of the pair of rollers, additional support frame is required. This design works out to be cheaper than the same width conventional single row conveyor with longer and larger rollers.
(ii) Curved sections: These are used for changing direction of the conveyor in the horizontal plane. In this section rollers are arranged radially. Two or more number of cylindrical rollers are used in place of one roller to reduce sliding action of the load on rollers (see Fig. 6.6.4). Minimum sliding action of the load on rollers can be achieved by using single tapered roller (V-roller), but as these are to be made from solid casting or forged section, are costly and seldom used.
(iii) Switches: Devices used in a roller conveyor to change the normal direction of the load or divert the load from the conveyor are called switches.