1. Space and the lack of it.

2. Boom arc or lack there of.

3. Added weight of additional components oincreasing weight of reclaimers counter weight- no t big issue overall but-

4. Poorer field of view below stacker boom for the operator.

5. Poor balance of boom -depending entirely on position of take up.

6. A hydraulic powered horizontal take up is simpler

7. Take ups are on the return side as a rule to avoid problems with carrying side of conveyor.

8. Additional Potential for belt or splice failure from forward and reverse operation of conveyor while stacking or reclaiming.

9. I am sure I missed something that Lyn, George or my other mentors on the board will point out. ■

Dear Mr. P C Tarey,

Generally one would use screw take-up with provision for hydraulic tensioner for setting of the belt tension, or similar arrangement.

One rarely comes across vertical gravity take-up for boom conveyor. It is not preferred due to varied reasons. However, I once saw stacker reclaimer supplied by famous company from East Asia, in Malaysian power station of TNB. The boom conveyor of this stacker cum reclaimer machine is equipped with VG. This is for the information of readers that such arrangement has been also used (though it may be rare).

It seems, functionally one has to take care of following aspects :

- The implication of boom luffing on such arrangement. That means vertical guide will not remain vertical unless it is of pendulum type mounting. If it is pendulum type then the damping system to quickly stop the oscillation.

- If the arrangement is not of pendulum type, the counter weight guides, when not vertical will also impose the horizontal thrust on the guides and it will also marginally alter the take-up force up to about 1% (cosine of half the inclination of boom. Considering that the guides will be vertical in mid position of the boom).

- The arrangement appears to be compact due to comparatively small take-up stroke (equivalent to the routinely used method). The only advantage is that the take-up force is always assured without setting etc. The take-up location is very close to the machine centre.

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 ■

I know an ongoing Australian job where there is a repeat order for a 30m boom radial stacker with a GTU. Can anybody beat that? ■

Further to my reply on the subject matter, I missed to mention following point.

In the event of belt snapping, the counter weight will fall. This fall should be arrested by sufficient resilient means, so that it will stop in reasonable distance and not abruptly, to restrict the impact force. The machine has to be designed considering the impact force. Also, safety aspect at ground level below take-up to be also given thought.

There will be also lateral inertial forces during acceleration and deceleration of the boom in slewing motion.

I have given the information to the readers, and this does not mean that I am suggesting or recommending such an arrangement.

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 ■

perhaps u r facing the problem of belt slippage problem at full load and u can not provide more tension in ur belt conveyor by screw take up. its a common problem in the boom conveyor of s/r running at high speed . we r facing the same problem in our limestone s/r but we redesign the conveyor and running since last 2 year. ifu want any suggestion required to this problem .

contact please: +919424972960 and email: rkkush71@yahoo.com

thanking you,

rkkushwaha

manager (mechanical) ■

Dear Mr. Rkkushwaha,

The simple screw take-up with manual tensioning is good enough for light duty conveyor of average application. The conveyor of heavier class or important installations (these also include boom conveyor), should have the tension measuring device. The boom conveyor is designed considering specific tension in belt, so that it does not slip with reference to wrap angle and friction coefficient between belt and pulley periphery. Therefore it is essential that the take-up device should impart tension as mentioned in the maintenance manual. One method is to tighten the belt by turning the screw and the load cell is part of the conveyor installation which will give indication when to stop tightening.

For heavier class of conveyor where it is difficult to tighten the screw due to large tension, the one of the practice is to make the screw free and shift the pulley by hydraulic tensioner. When the desired force (oil pressure) is reached, the screws are brought in action and pulley remains located (locked) at that place.

For such screw take-up the adjustment of tension is to be done when it is empty and standstill. The system can have sophistication such as monitoring of tension and giving audio visual alarm at certain limit and again if this reaches to second limit, it will stop the conveyor.

Ishwar G. Mulani

Author of book : Engineering Science and Application Design for Belt Conveyors

Author of book : Belt Feeder Design and Hopper Bin Silo

Tel. No. : 0091 (0)20 2587 1916

Email : parimul@pn2.vsnl.net.in ■

hi,

we are also facing problem in boom conveyor belt tracking despite full screw takeup tensioning.

Belt is not in the centre even in noload condition.

Your suggestions shall be highly appericiated.

ramesh kumar ■

Dear Shri Ramesh Kumar,

If the conveyor is constructed (erected) properly then belt should not have a tracking problem. This is particularly influenced by the pulleys axis orientation, idlers axis orientation in horizontal plane and vertical plane, correctly constructed belt joint, belt quality etc. You can also use pulleys with crowning of permissible level. If you have a facility for self checking you may do so. Or contact some reputed erection agency and they shall be useful to you to solve your problem. It is not proper to make any specific suggestion without seeing the equipment etc.

Ishwar G. Mulani

Author of book : Engineering Science and Application Design for Belt Conveyors

Author of book : Belt Feeder Design and Hopper Bin Silo

Tel. No. : 0091 (0)20 2587 1916

Email : parimul@pn2.vsnl.net.in ■

Originally Posted by I G Mulani

Dear Shri Ramesh Kumar,

If the conveyor is constructed (erected) properly then belt should not have a tracking problem. This is particularly influenced by the pulleys axis orientation, idlers axis orientation in horizontal plane and vertical plane, correctly constructed belt joint, belt quality etc. You can also use pulleys with crowning of permissible level. If you have a facility for self checking you may do so. Or contact some reputed erection agency and they shall be useful to you to solve your problem. It is not proper to make any specific suggestion without seeing the equipment etc.

Ishwar G. Mulani

Author of book : Engineering Science and Application Design for Belt Conveyors

Author of book : Belt Feeder Design and Hopper Bin Silo

Tel. No. : 0091 (0)20 2587 1916

Email : parimul@pn2.vsnl.net.in

"You can also use pulleys with crowning of permissible level."

Dear sir,

I was told by a pulley manufacturer before few years that crowning is stopped.

I also feel that he may be correct because it may cause different tension at the centre of the belt and at edge of the belt, especially for steel cord belts.

Please advice. ■