THe 10% slope will require a holdback device when the conveyor is at rest. The short conveyor has a demand power of 34 kW and the larger has a demand power of about 266 kW.

Although a brake coud be used to hold the load, I, for one, recommend otherwise for safety and reliability. Brakes need more maintenance and adjustment to do a proper job.

You do not provide enough information on the conveyors and the need for stopping with some form of timing or displacement control. Do you need to sequence a stop that will prevent ore buildup that can possibly plug the chute. Is the small unit feeding or receiving from the big? Are they in some other sequence?

Of course there are many other uses for brakes. It is near impossible to guess the many applications you may be thinking about

A little enlightenment is encouraged.

We are specialist in all forms of brake systems.

Lawrence Nordell

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com ■

Dear Shri Sachin Arora,

As is universally known, brake is for timely stopping of most of the items. We have brakes in our vehicles so that vehicle can be stopped in a reasonable time or distance. In case of conveyor, you have to find the conveyor naturally stopping time (without brake). As a designer you have to decide your permitted stoppage time. If the conveyor is stopping on its own without brake within permitted time, then brake is not necessary. If it is exceeding the permitted value then one has to provide the brake. The permitted time is to be decided in context of safety considerations and the material that will accumulate at the junction of conveyors due to difference in stoppage time. The kind of conveyors you have mentioned, you need to analyse the stoppage issue for longer conveyor. For the short conveyor, it may stop on its own in a few seconds.

The stoppage time to be analysed with respect to full load capacity, part load capacity, empty condition and range of variation in artificial friction coefficient for conveying.

If your intention is to prevent roll back of the conveyor, then hold back is better device. However, if the conveyor is reversible, then one has to opt for brake instead of holdback.

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 ■

Hi Sachin..

The long conveyor has the same slope and duty as the shorter one. Therefore they stop in approximately the same length of time. So unless you have strange conveyor profiles, you don't need brakes on either, in order not to overload the transfer chute between them.

Cheers

LSL Tekpro ■

Dear Mr. Sachin,

Brake is provided in a long conveyor dischaging in a shorter one.But one should ckeck the coasting time & then brake to be provided.

Mr. Bhatnagar is alreaded stated the same also.

Regards.

A.Banerjee ■

Hi again Sachin..

Forgot to add:

I had good success in controlling relative coasting times by adjusting counterweight mass on the upstream belt in one of our applications.

Despite my sheltered life as Larry once put it, by reducing the counterweight, I was able to increase the sag a bit. This had a surprising effect on decreasing the coasting time.

As a result, we were able in our case, to disconnect the brake on the upstream conveyor and operate without it.

Good luck

LSL Tekpro ■

Well blow me down but I've just got my arm caught in a conveyor!

Is there a brake handy? ■

Poor thing John...

But as Graham Shortt used to say.. It matters not whether you get killed in a conveyor stopping in 15 seconds, or in 10 seconds.

In both cases you are unfortunately, stone dead.

For example if you go around the tail pulley 10 times or 15 times you still end up being just as squished.

I actually have never in my (sheltered) life known of a conveyor brake preventing someone leaving this mortal coil.

Hope you get better soon John.

Cheers

LSL Tekpro ■