The selection of a take-up mainly depends on the size and the dynamics of the system. Simple systems are quite normaly eqipped with a fixed take-up (screw type, fixed winch type or similar). With this kind of take-up one may theoretically face higher peak loads than with a gravity type take-ups: With the latter the maximum load in the belt under the assumption of static conditions is limitted to the force of gravity introduced by the take up. So the long distance belt conveyor with the New Caledonia nickel project was once equipped with a uge gravity type take-up.

Practical experience shows, however, that the real acting dynamic peak loads can be much higher also with a gravitiy take-up, since due to the forces of inertia the gravity weight can not be lifted as quick as the load in the belt increases some times. With the same reasons automatic tensioning devices (usually winch type) which shall adjust the belt tension as per the actual load in the belt act much to slow.

In so far gravity type take ups work fine as well as fixed take-ups do. If one wants to do a layout for a long distance conveyor a dynamic calculation is required to find the optimum. ■

mahmud

Screw take-up are very limited to relatively short conveyors. For example at our operation we limit the conveyor length for screw take-ups to 200 foot centers. Exceding that we then either go with a gravity take-up or a hydraulic driven take-up on a trolley, based on height availability at the take-up location. (height restriction due to mining operation)

In each and every case a formal calculation must be done to determine the amount of take-up that is required. It is all based on the amount of stretch that your belt will experience during the normal operation of the system.

Gary Blenkhorn ■

Morning Mahmud..

(I seem to remember this topic from a previous thread..maybe have a look to see previous comments.)

I also remember previously mentioning along the lines of the written rules being different from what you can actually do in practice.

For example, we have a 1.2km long 900mm wide 1000t/h overland conveyor with a fabric belt on it.

The take-up length is 18m, and it is fitted with a very basic winch.

What is somewhat odd is that we simply winch the take-up carriage to about 15m along the travel and lock it there and leave it locked in that postion.

So in other words it acts like a fixed take-up which many people would say should be limited to a conveyor length of say 200ft as per Gary above.

I have used this simple take-up system on quite long shiftable conveyors with steelcord belts as well. (You don't want to have anything fancy on shiftable conveyors)

For overlands of 4km and greater I normally use gravity take-ups with a capstan brake though. This works great..

Regards

LSL Tekpro ■

Dear Mr. Mahmud,

Mr. Holger has given detailed information. One can investigate about the type of take-up based on following general observations :

1) For the conveyor, which is say up to 30 m length, one may find screw take-up.

2) If the conveyor is longer than 30 m, and if there is space for installation, one may observe vertical gravity take-up. However, vertical gravity take-up will have a difficulty if the take-up stroke requirement is say more than 7 to 8 m.

3) If the conveyor is longer than 30 m, and if there is space for installation, one may observe horizontal gravity take-up. However, horizontal gravity take-up will have a difficulty if the take-up stroke requirement is say more than 15 m.

4) Conveyor also uses winch take-up device.

It is very difficult to describe exact selection procedure in the forum, because it will be very length affair, and there are finer aspects about the selection of the most suitable type of take-up.

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 ■

Good morning Mr Mulani..

I find it very interesting, albeit a bit strange, that you imply a maximum length of a conveyor to use a screw (i.e. fixed type) take up to only 30m when I have had no problem using the fixed type on conveyors up to 1.2 kilometres even with fabric belts.

For shorter conveyors with concave radii I never use fixed or screw take-ups, and this is a far more important criterion to me than the length of the conveyor.

Maybe you can tell us why you advocate the 30m maximum length.

Thank you

LSL Tekpro ■

Kahlid

The 1.2km conveyor is a total success, as are my shiftable conveyors with fixed take-ups. To imply that I don't understand conveyor starting technology is a totally pathetic insult. I trust you will apologise.

LSL Tekpro ■

Khalid

You have now clearly demonstrated to the Forum that your opinion is purely insulting and derogatory.

Shame on you Khalid..

LSL Tekpro ■

Referring to my earlier reply, I draw kind attention of the readers to the following points :

a) My information in serial no.1 pertains to screw take-up (which is one type of fixed length take-up). It does not apply to all take-ups working on the basis of fixed length of belts. The screw take-up is mentioned very clearly.

b) Winch take-up is other type, which works on principle of fixed length of belt during operation. Such take-up can be used for any length of conveyor. Although its functional principle is similar to screw take-up it is not a screw take-up. This item has been mentioned in serial no. 4 of my earlier reply.

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 ■