Dear Shri Chetan,

My suggestion would be to put horizontal gravity take-up at tail end.

You would be mostly using EP belt and if you install screw take-up, then the IS, BS practice etc. is to have approximately 2% stroke + 0.25 m. This amounts to nearly 2650 mm stroke for which screw take-up would be difficult. Alternatively, if you have got a nylon-nylon belt then the situation would be quite adverse as it would have 2.5% instead of 2%.

If you do not have space for installing the counter weight unit immediately behind the tail pulley, you can use the necessary rope and sheaves to have this take-up mass anywhere you choose (similar to old time railway signaling). This rope when taken in this manner should be preferably taken within the pipe for 100% safety of the operating personnel.

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 25882916 ■

Of course, for only 100 te/hr of grain and 120m long you could use a chain conveyor and forget all about rubber belts with, according to Mr Mulani, its 2.65m of tension. And it would be totally enclosed.

Just a thought. ■

For this application you may need 2.5 to 3.5 meters (or more) of take-up travel depending on the fabric belt type and construction.

If you have the patience you can design a screw take-up system with multiple mounting holes so that the frames (having typical 1.2 meters stroke) can be relocated when they run out of travel. Eventually you will come to a stable position of the srew take-up system.

A better solution is a hydraulic take-up system; the tail pulley on a take-up carriage pulled, through wire rope reeving, by a constant pressure hydraulic cylinder. ■

With a 1000mm belt carrying 100 tph you're not going to stretch the belt very far. Try a screw. ■