Conveyor Pulley Load

[sdz]

I am working on a design for a drive pulley support for a conveyor with large belt loads. In my initial design I assumed the belt load acting in the middle of the drive pulley. My checker thinks, and they are probably right, that the design should include either or both;
- load acting at 50mm off design centerline
- a lateral force arising from the above

The belt tension load (2 belts) is about 1400kN
. ---->
O 1400kN
. ---->

Do you agree? How large should the lateral force be? Should they be applied together or separately?

 

[PersonalProfile]

Mechanical brethren should (must) make it clear for you.
Some designers like to allow some number for drift, though generally, if it can take the normal load, the drift wont break it either.
For a curve ball, even if the belt was tracking in the centre, it doesnt mean the centre of force would be there (consider non equal distribution of force in the carcass / cords, which is real, rather than theorectical assumption of symmetrical).
Our design code in AUS, AS4100, states 2.5 % - this is not there to allow for ill defined lateral loading (though for buckling of section), though provides some margin (- mechanical engineer - dont concern myself so much with finer details of structural design) for lateral load, regardless.
Considering the nature of industrial plant and its opperation, I would suggest the SF should be suitable, such that this is not an issue, regardless.
Regards,
Lyle

 

[sdz]

Lyle,
Where is that clause in AS4100? Is that the nominal load for bracing to restrain LT buckling?

 

[EngineerTex]

I wrote a whole post, then re-read your post and maybe I'm no longer certain that I know what you were asking. So I deleted it and am trying again.

Is this for a drive roller for the conveyor belt? Or is this for some sort of v-belt drive pulley that is connected to the drive roller of the conveyor belt? When you say lateral, do you mean a force that acts axially to the roller? When you say off-center, do you mean that the two legs of the belt will be tensioned differentially? (they will) Or do you think that the belt will wander away from the midpoint of the drive roller?

Unless you're designing the support for an idler pulley, the concept behind a drive belt is that one leg of the belt carries the load and the other leg doesn't. In other words, the tension in the belt is NOT uniform throughout. The tension of the belt carrying the conveyed material is SIGNIFICANTLY higher than the tension of the belt leaving the driving pulley.

The exiting leg will be in some unknown state of slack. But it shouldn't be too hard to figure out. Do it this way:

1) Consider all belt loads acting on the pulley tangentially to the outside diameter
2) Pretension load from a spring-loaded idler will be distributed throughout the entire belt.
4) Don't forget to include the weight of the belt. That may be significant on something this large.

Take all that and translate the load vectors back to the structure you're designing.

-T


Engineering is not the science behind building. It is the science behind not building.

 

[sdz]

Tex, This is for a 2nd drive pulley.

The checker has considered a lateral load (i.e. perpendicular to the belt direction, parallel to the axis of the pulley) that was not specified by the mechanical engineer.