Thanks for this post.

Stringers waste steel. Normal span & the point loads imposed from the idler sets call for a substantial stringer section.

Consider the height from the stringer to the deck, consider the stringer is supported on lighter section legs than the stringer is cut from. It doesn't take a Masters in Mathematics to recognise that individual freestanding idlers are then lighter per metre than stringer mounted systems.

With a bit of design intent the freestanding stringers would be able to sustain the idler drag by interconnecting them with sheet metal covers. Conveyor designers throughout the decades have despised stringers in all known shapes.

If you do consider the electrical cable requirements you will eventually come to the maxim I had confirmed by German colleagues; "Just tell us where the cables are going & we'll sit the conveyor on top." It always works out that way so why worry about mundane things like stringers after all. ■

Hi rekhawar,

In the mining stopes we use individual idlers supported from a trapeze supported from the handing wall (roof). To accommodate horizontal friction, the sets of idlers are tied together with post-tensioned wire.

With a bit of thought you don't need components in bending and compression. A whole lot can be done with tension components, and they are as cheap as chips.

Regards - Sgt John.rz

www.latviantourists.com.au ■

Hi Rekhawar,

For my option the idler drag force can be sustained by sheet metal covers they are needed by the product charateristics. otherwise the stability can be provided by windboards.

The intetion is to use all the components to provide a stuctural function. Flat deck sheets would only provide lateral bracing. ■

Dear Shri Rekhawar,

Stringers are required to mount the idlers and create proper belt profile. Therefore, it is possible that people can fulfill this functional need by differing arrangements. However, based on the experience in the industry following two types are widely used :

1) Continuous stringers (either channel or angle). Most of the stationary conveyors will have this type of arrangement. In case the idlers are mounted on gantry top chord (members), then the stringer will be part of the gantry. Such continuous members will have certain benefits like necessary strength of conveyor frame, easy to achieve alignment between members, to facilitate the fitting of deck plate when needed and so on.

2) Discontinuous stringers are commonly used in shiftable conveyors. In such conveyors there is a conveyor module say about 4.5 to 6 m length. In this case, there will be gap between two stringers in accordance with the idler pitch. In case of shitable conveyors such arrangement is must other wise the conveyor will be difficult t shift in mechanized and quick manner. Here, the continuous rail integral to the flexibly connected module, helps in achieving the reasonably required alignment.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25871916 ■