Dear Mr. Urwithlip,

Regarding your question with respect to the multy driven belt:

I suppose you mean a belt with booster drives and not the system with two driven head end pulleys combined with a driven tail-end pulley.

Using a sysyem with two driven pulleys at the head-end eventyually cimbined with a driven tail-end pulley the effective use ot the belt strenght will be extended from 60% up to 90% (T1:T2) Teff. =T1-T2

There are two type of booster driven conveyors: the conveyors with a tripper type of booster drive and the TT system or Piggy Ridge conveyor.

The first system however is in fact not an un-interrupted conveyor. The product will leave the belt for a second to be loaded again on the same belt. Only the return part of the belt is uninterrupted. The disadvantage of this system is that at every booster drive position the complete unloading and loading provisions are required.

The other system; the TT conveyer really gives an un interrupted transport of the product.

With the systems as mentioned above the reduction of the required belt strenght and the elastic elongation will make this solution in many cases much more interesting

Both systems allow to install several intermediate drives reducing the tensions in the belt on critical positions. The tensions can be controlled and the intermediate drives can be activated according to the occured resistance on every individual traject.

This means that you do not have to install the St.3500 belt; a belt with a much lower strenght in this situation will fullfill your requirements.

If you can give me more details I can probably propose you a suitable solution.

Kind regards

ist

Innovatief in Stortgoed Techniek

Innovativ in Schuttgut Technik

Johan Brands

The Netherlands

E-Mail

i.s.t@wanadoo.nl ■

Dilip..

You can select a multiple (normally dual) pulley drive arrangement if it reduces the overall system tension thereby enabling you to use a cheaper belt, and more economical pulleys.

The limitations of this are however that you must always maintain no more than 2% sag anywhere in the system, The belt tension must never tend to be negative during stopping.

Also, the doubling up of drive stuff tends to nibble away the benefits

You have to weigh up all the merits for each conveyor through thorough analysis

LSL Tekpro ■

Booster drives offer great advantages associated with tension control including (but not limited to) minimizing belt tension that reduces the belting cost.

The writer has used booster drives of the tripper type as well as the belt-on-belt type. The belt-on-belt type offer continuous conveying while the tripper type requires lifting the material and dropping it back onto the belt. The latter system allows instrumenting the LT bend pulley with load cells to monitor the T2 belt tension. The monitoring may be interlocked with the drive, to control output torque, to acheive a desired tension distribution. Such tension control facilitates horizontal curving conveyors minimizing the tension variation that causes belt wander in the trough of the horizontally curving path.

Three examples where we have used booster drives to an advantage:

- Long 3-Flight Conveyor System, 5.1 miles (8.191 km), 36" (914 mm) BW.

Customer specs required fabric belting at this system. Each single flight required a fabric belt that was marginally troughable and very difficult to train. The booster drive solution allowed a belt of lesser strength that was easily troughable and more stable in the trough.

- Long Overland Conveyor, 1.73 miles (2.79 km), 1600mm BW.

This system used a 1000 kW head drive and 3 @1000 kW boosters for a total of 4000 kW of drive power. This allowed a modest more economical steel cord belt.

- Long Overland Two-Way Conveyor, 1.71 miles (2.75 km), 42" (1067mm) BW.

This conveyor carries limestone from the Quarry to Cement Plant #1, on the top side, and clinker from Cement Plant #1 to Cement Plants #2 and #3 on the return side. This conveyor follows an irregular path both vertically and horizontally featuring 9 horizontal curves compounded by numerous vertical curves. The drives are 600 HP (448 kW) at the head end, 400 HP (298 kW) "Smart Booster" at the top side, 200 HP (149 kW) "Natural Booster" at the return side. The booster drives strategically located and controlled are essentiall in controlling the tension distribution which facilitates a horizontally curving conveyor that minimizes belt wonder in the trough.

Booster drives especially with tension control have facilitated solutions that were not previously considered.

Joseph A. Dos Santos ■