Hi There,

I am trying to calculate the take up weight for one conveyor. As I understand, I should check two criteria’s against sizing the take up.

1- Minimum tension in order to build the determined sag in belt conveyor between idlers.

2- Minimum tension required in slack side T2 of the drive in order to prevent the slippage in drive during start up (and operation).

However, when I checked calculation performed by Krupp or Swedalla for similar conveyors my calculated take up weight is less than, calculated take up weight by Krupp or Swedalla. Our other calculation output like power is very similar. Also when I select their take up weight I reach the tension in the belt very close to their calculated tension.

These calc are for conveyor with head drive pulley and elevating conveyor with gravity take up.

I believe they oversize their take up weight by 1.5 to 1.7 safety factor. I am after recommended practice of safety factor for over sizing the take up weight? If somebody could help me?

Thanks and Best Regards

BJSamim ■

Hi There,

I am trying to calculate the take up weight for one conveyor. As I understand, I should check two criteria’s against sizing the take up.

1- Minimum tension in order to build the determined sag in belt conveyor between idlers.

2- Minimum tension required in slack side T2 of the drive in order to prevent the slippage in drive during start up (and operation).

However, when I checked calculation performed by Krupp or Swedalla for similar conveyors my calculated take up weight is less than, calculated take up weight by Krupp or Swedalla. Our other calculation output like power is very similar. Also when I select their take up weight I reach the tension in the belt very close to their calculated tension.

These calc are for conveyor with head drive pulley and elevating conveyor with gravity take up.

I believe they oversize their take up weight by 1.5 to 1.7 safety factor. I am after recommended practice of safety factor for over sizing the take up weight? If somebody could help me?

Thanks and Best Regards

BJSamim ■

Hello Herminigildo.Sia,

To find out the quantity of counter weight, designer has to find out the belt tension at the location of take-up (return run), for following situations :

1) Belt tension at that location during steady state condition.

2) Belt tension at that location during starting condition.

3) Belt tension at that location during stopping condition.

The aforesaid belt tensions so calculated should be satisfying the need for power transmission at drive pulley/s. The aforesaid belt tensions so calculated should also be satisfying the need for minimum tension with respect to sag.

Use the highest value of the aforesaid tensions at the location of take-up, to work out the take-up force on take-up pulley. The take-up force at take-up pulley will be twice the highest tension at that location. In case of VGT, the counterweight will be the same as the take-up force (minus take-up pulley weight, frame weight etc.). In case of horizontal gravity take-up, the counter weight will be in accordance with the mechanical advantage in the take-up system.

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.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: parimul@pn2.vsnl.net.in ■

Hello Herminigildo.Sia,

To find out the quantity of counter weight, designer has to find out the belt tension at the location of take-up (return run), for following situations :

1) Belt tension at that location during steady state condition.

2) Belt tension at that location during starting condition.

3) Belt tension at that location during stopping condition.

The aforesaid belt tensions so calculated should be satisfying the need for power transmission at drive pulley/s. The aforesaid belt tensions so calculated should also be satisfying the need for minimum tension with respect to sag.

Use the highest value of the aforesaid tensions at the location of take-up, to work out the take-up force on take-up pulley. The take-up force at take-up pulley will be twice the highest tension at that location. In case of VGT, the counterweight will be the same as the take-up force (minus take-up pulley weight, frame weight etc.). In case of horizontal gravity take-up, the counter weight will be in accordance with the mechanical advantage in the take-up system.

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.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: parimul@pn2.vsnl.net.in ■

Dear Experts,

I am measuring the sag between the successive carrying frames or the return frames at the horizontal portion of the conveyor profile, when the belt is stopped & is empty.

I am adjusting the counter weight so that the above measurement is not less than 1%.



Request your comments please.

Regards, ■

Dear Experts,

I am measuring the sag between the successive carrying frames or the return frames at the horizontal portion of the conveyor profile, when the belt is stopped & is empty.

I am adjusting the counter weight so that the above measurement is not less than 1%.



Request your comments please.

Regards, ■

Originally Posted by sganesh

Dear Experts,

I am measuring the sag between the successive carrying frames or the return frames at the horizontal portion of the conveyor profile, when the belt is stopped & is empty.

I am adjusting the counter weight so that the above measurement is not less than 1%.



Request your comments please.

Regards,

That is only one factor sganesh. You must calculate the tensions and determine if you have enough take-up to prevent slipage at the drive during start-up. ■

Originally Posted by sganesh

Dear Experts,

I am measuring the sag between the successive carrying frames or the return frames at the horizontal portion of the conveyor profile, when the belt is stopped & is empty.

I am adjusting the counter weight so that the above measurement is not less than 1%.



Request your comments please.

Regards,

That is only one factor sganesh. You must calculate the tensions and determine if you have enough take-up to prevent slipage at the drive during start-up. ■

I believe you mean to say:

"adjusting the counter weight so that the above measurement is not more than 1%. Having a sag value less than 1% poses no problem. Having a sag greater/more than 1% means the belt will absorb more power due to the higher belt flexure.

CEMA and other standards have noted to keep the sag below 2%. When power is calculated by the CEMA 5th edition method, you can observe a higher power will be required based on the "ky" factor, based on normal running condition. When stopping with higher sag, this will cause faster stopping time and largerr counterweight travel. The travel value can become extreme with long overlands that accumulate large belt storage between idlers. Special design factors must be applied to limit the sag in such cases.

Belt slip is another condition. ■

I believe you mean to say:

"adjusting the counter weight so that the above measurement is not more than 1%. Having a sag value less than 1% poses no problem. Having a sag greater/more than 1% means the belt will absorb more power due to the higher belt flexure.

CEMA and other standards have noted to keep the sag below 2%. When power is calculated by the CEMA 5th edition method, you can observe a higher power will be required based on the "ky" factor, based on normal running condition. When stopping with higher sag, this will cause faster stopping time and largerr counterweight travel. The travel value can become extreme with long overlands that accumulate large belt storage between idlers. Special design factors must be applied to limit the sag in such cases.

Belt slip is another condition. ■

Originally Posted by nordell

I believe you mean to say:

"adjusting the counter weight so that the above measurement is not more than 1%. Having a sag value less than 1% poses no problem. Having a sag greater/more than 1% means the belt will absorb more power due to the higher belt flexure. ........................

.................Belt slip is another condition.

Thank you Mr.Gary & Mr.Nordel.

I thought excessive tension ( less than 1% ) will reduce the joints life and reduced the counter weights to have the sag = 1%. I did not face any slippage problem so far.

Regards, ■

Originally Posted by nordell

I believe you mean to say:

"adjusting the counter weight so that the above measurement is not more than 1%. Having a sag value less than 1% poses no problem. Having a sag greater/more than 1% means the belt will absorb more power due to the higher belt flexure. ........................

.................Belt slip is another condition.

Thank you Mr.Gary & Mr.Nordel.

I thought excessive tension ( less than 1% ) will reduce the joints life and reduced the counter weights to have the sag = 1%. I did not face any slippage problem so far.

Regards, ■