Belt tensioning has been stretched out in many previous threads so have a search and see what you can pull out.■

Belt tensioning has been stretched out in many previous threads so have a search and see what you can pull out.■

Dynamic take up winches that adjust tension based on the load conditions have been around for many years in the underground coal industry. They usually form part of a belt storage system which allows maingate or panel belts to be extended or shortened in 100-200M sections. Given the operation of these conveyors where the load varies from no load to fully loaded and the fact they are invariably quite long and designed with fabric belt that stretches much more than steel cable reinforced belt the need is obvious as there is a great deal of tension dynamics in the system. In some overland conveyors particularly those that rise and fall over their length there is a need to have some control over the take up tension during starting and stopping. So in answer to your posting, it depends on the application. In most cases it is not worth the additional cost, in other cases it is an essential part of the design.

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Dynamic take up winches that adjust tension based on the load conditions have been around for many years in the underground coal industry. They usually form part of a belt storage system which allows maingate or panel belts to be extended or shortened in 100-200M sections. Given the operation of these conveyors where the load varies from no load to fully loaded and the fact they are invariably quite long and designed with fabric belt that stretches much more than steel cable reinforced belt the need is obvious as there is a great deal of tension dynamics in the system. In some overland conveyors particularly those that rise and fall over their length there is a need to have some control over the take up tension during starting and stopping. So in answer to your posting, it depends on the application. In most cases it is not worth the additional cost, in other cases it is an essential part of the design.

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Originally Posted by john zhu

static calculation takeup tension vs actual dynamic value

.............1. can we adjust the tension dynamiclly with the load vary?

Dear Mr.John ZHU,

I feel that there could be electrical operated screw take up or hydraulic operated screw take up.

By having feed back from the weigh scale you may be able to adjust the tension in the conveyor.

I do not know such system is existing any where. This is only my opinion.

Request the comments from the experts or end users, if someone is already using the above concept.

Thanks & regards, ■

Originally Posted by john zhu

static calculation takeup tension vs actual dynamic value

.............1. can we adjust the tension dynamiclly with the load vary?

Dear Mr.John ZHU,

I feel that there could be electrical operated screw take up or hydraulic operated screw take up.

By having feed back from the weigh scale you may be able to adjust the tension in the conveyor.

I do not know such system is existing any where. This is only my opinion.

Request the comments from the experts or end users, if someone is already using the above concept.

Thanks & regards, ■

In my understanding, take-up force is a minimum system pretenison force which is required for the drives to be able to transmit power/ torque in the conveyor system with minimum slip if at all; for any capacity up to maximum system design capacity. Take up force is also calculated to minimize belt sag. It really depends on the application, but if the application involves saving energy and reducing wear on mechanical items, Variable speed drives can also be used. but variable speed drives are not cheap and have their down side aswell. ■

In my understanding, take-up force is a minimum system pretenison force which is required for the drives to be able to transmit power/ torque in the conveyor system with minimum slip if at all; for any capacity up to maximum system design capacity. Take up force is also calculated to minimize belt sag. It really depends on the application, but if the application involves saving energy and reducing wear on mechanical items, Variable speed drives can also be used. but variable speed drives are not cheap and have their down side aswell. ■

Hello john zhu,

Proper design for belt conveyor considers varying situations, and design is done such that entire conveyor design (including take-up design) will ensure proper performance of belt conveyor. In general conveyor should be designed for following nine situations:

1) Conveyor steady state running: When empty, 50% load and 100% load (i.e. 3 cases).

2) Conveyor starting (acceleration) state: When empty, 50% load and 100% load (i.e. another 3 cases).

3) Conveyor stopping (deceleration) state: When empty, 50% load and 100% load. (i.e. another 3 cases).

In all these situations drive pulley/s should be able to transmit applicable torque, sag should not exceed maximum chosen values (in conjunction with conveying friction coefficient), etc. You may refer to standards, interact with manufacturers, contact conveyor designer, etc. for more understanding.

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 john zhu,

Proper design for belt conveyor considers varying situations, and design is done such that entire conveyor design (including take-up design) will ensure proper performance of belt conveyor. In general conveyor should be designed for following nine situations:

1) Conveyor steady state running: When empty, 50% load and 100% load (i.e. 3 cases).

2) Conveyor starting (acceleration) state: When empty, 50% load and 100% load (i.e. another 3 cases).

3) Conveyor stopping (deceleration) state: When empty, 50% load and 100% load. (i.e. another 3 cases).

In all these situations drive pulley/s should be able to transmit applicable torque, sag should not exceed maximum chosen values (in conjunction with conveying friction coefficient), etc. You may refer to standards, interact with manufacturers, contact conveyor designer, etc. for more understanding.

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 ■

Has anyone heard of adjusting the wrap in sympathy with the tension requirement?

It might be worth a thesis or two for some bright young souls. ■

Has anyone heard of adjusting the wrap in sympathy with the tension requirement?

It might be worth a thesis or two for some bright young souls. ■

1. It is possible to adjust the tension dynamically with load using a Hydraualic or Motorised take up device.

2. The tension for limiting the belt sag to 1% is calcualted at the Design Capacity. This limiting tension also reduces as the laod reuces to 20% of Design capacity, therefore the question of sag dropping below the allowable limit will never arise.

3. The only disadvantge in running at higher tensions at lower loads is the stress to all mechanical components, which in any case are to be designed for the Designed Capacity. Therefore, this apprehension is out of place.

4. Of course, by iterating the conveyor claculation at various loads, the required minimum take up tension at various loads can be calculated.

Originally Posted by john zhu

static calculation takeup tension vs actual dynamic value

Dear experts:

As we all know that we set the takeup tension according to static calculation such as starting, running, stoping and braking. but all these tension values are based on rated load such as 4000 t/h (or 5000, 6000), but when the load changed to 20% or some like that of rated load, the tension will adjust automatic to keep running value of rated load, could anyone can give some coments:

1. can we adjust the tension dynamiclly with the load vary?

2. if we don't adjust and keep the takeup tension as static cal ones, what will be happen? does the belt sag will be less 1%? what will be happen with less sag?

3. are there any other disadvantages of the system when it is running with less load but high takeup tension?

4. is there an experinced format between takeup tension and actual load(not static cal)?

look forward to your reply!

thanks in advance!

■

1. It is possible to adjust the tension dynamically with load using a Hydraualic or Motorised take up device.

2. The tension for limiting the belt sag to 1% is calcualted at the Design Capacity. This limiting tension also reduces as the laod reuces to 20% of Design capacity, therefore the question of sag dropping below the allowable limit will never arise.

3. The only disadvantge in running at higher tensions at lower loads is the stress to all mechanical components, which in any case are to be designed for the Designed Capacity. Therefore, this apprehension is out of place.

4. Of course, by iterating the conveyor claculation at various loads, the required minimum take up tension at various loads can be calculated.

Originally Posted by john zhu

static calculation takeup tension vs actual dynamic value

Dear experts:

As we all know that we set the takeup tension according to static calculation such as starting, running, stoping and braking. but all these tension values are based on rated load such as 4000 t/h (or 5000, 6000), but when the load changed to 20% or some like that of rated load, the tension will adjust automatic to keep running value of rated load, could anyone can give some coments:

1. can we adjust the tension dynamiclly with the load vary?

2. if we don't adjust and keep the takeup tension as static cal ones, what will be happen? does the belt sag will be less 1%? what will be happen with less sag?

3. are there any other disadvantages of the system when it is running with less load but high takeup tension?

4. is there an experinced format between takeup tension and actual load(not static cal)?

look forward to your reply!

thanks in advance!

■

The hydro (fluid) coupling does not influence the drive friction. It does influence the drive traction ratio T1/T2. The traction ratio can be altered by the couplings behavior, but not the pulley to belt fricition dynamics.

Conveyor Dynamics, Inc. (CDI) and other consultants, as well as major coupling manufacturers have developed dynamic simulation of the fluid dynamc response according to individual coupling designs and laboratory measurement of the hydrodynamic action of the coupling during acceleration and deceleration. (K or J factor torque transmission coefficients). ■

The hydro (fluid) coupling does not influence the drive friction. It does influence the drive traction ratio T1/T2. The traction ratio can be altered by the couplings behavior, but not the pulley to belt fricition dynamics.

Conveyor Dynamics, Inc. (CDI) and other consultants, as well as major coupling manufacturers have developed dynamic simulation of the fluid dynamc response according to individual coupling designs and laboratory measurement of the hydrodynamic action of the coupling during acceleration and deceleration. (K or J factor torque transmission coefficients). ■

Hi there John

I did a 3.4 Megawatt incline conveyor which either had to do 1140t/h or twice this i.e. 2280t/h

I didn't want to have full slack-side tension on it all the time so designed a dual tension counterweight tower.

The cwt rope was double reeved when it was at the upper half of its travel, but for higher capacity, I lowered it, and using a steel lump clamped to the rope which snagged the rope sheeve, turned it into a single rope cwt, effectively doubling its mass.

It worked!

Cheers

LSL Tekpro ■

Hi there John

I did a 3.4 Megawatt incline conveyor which either had to do 1140t/h or twice this i.e. 2280t/h

I didn't want to have full slack-side tension on it all the time so designed a dual tension counterweight tower.

The cwt rope was double reeved when it was at the upper half of its travel, but for higher capacity, I lowered it, and using a steel lump clamped to the rope which snagged the rope sheeve, turned it into a single rope cwt, effectively doubling its mass.

It worked!

Cheers

LSL Tekpro ■

The french have done it better using a water tub. Fill and discharge according to your needs.

A number of counterweght dynamic tension schemes have been hatched and have been tried. Motorized apply and withdrawl masses are not uncommon with big systems that need an alternative to a constant tension. Be it hydraulics, moving mass, capstan boost, and more exotic devices. ■

The french have done it better using a water tub. Fill and discharge according to your needs.

A number of counterweght dynamic tension schemes have been hatched and have been tried. Motorized apply and withdrawl masses are not uncommon with big systems that need an alternative to a constant tension. Be it hydraulics, moving mass, capstan boost, and more exotic devices. ■