The easiest way to reduce sag is to increase the weight of the counterweight. You need to look at both the running sag and the acceleration sag. Typical conveyor designs have the stringer channel legs turned in and leg supports on the outside of the channel preventing the situation you have. Typically return idler support hole centers are BW+9" so for your installation they should have been 42"+9" = 51". Putting UMHW or any other material will only delay the inevitable. From looking at your sketch I would think that you will have an issue with bolts as well. If your sketch is to scale then your belt to channel location looks much too close in relation to the belt. Even with the legs turned out you should have approx 49" between the channels giving you about 3 1/2" clearance to the belt. I personally would not accept this as a good design.

Your only way out of this is to increase your counterweight or in the case of a hydraulic take-up increase the pressure. Ideally if this has not been fabricated I would be changing the design for sure.

I also moved your post to a more appropriate location where it will get more views. ■

The probable contact zone would be at mid span. From the drawing it seems that there is plate support between the stringer and the hollow section upright. This is strange.

If you fit low friction material in the gap between the upright and the belt edge you severely increase the rubbing on the basis of diminished clearance for the belt to wander into. You will also need to provide a reinforcing backing structure to stabilise the rubbing contact. This might prove more expensive than doing the job properly and increasing the width between supports.

What can happen will happen.

More feedback is required on this one. This thread starter has recognised the rub situation. Is this a refit on an existing structure, a newbuild or a new structure over existing hold downs etc etc?

American dimensions are shown on the sketch so perhaps a 1050mm belt has been chosen. Using a 1000mm belt would help and using troughed idlers would help more. Even then it doesn't look good and the recommended redesign must be considered. ■

I agree with John. If we had more details we might be able to help you better. Just looking again - you might be able to turn the legs 180 degrees and move the tube farther from the belt. But without knowing all the details this may not be possible. ■

Fire Hazard :

If belt is continously rubbing with the proposed UHMW liners, there could be a chance of fire due to prolonged rubbing.

Having standard space on both sides of the belt is highly recommended. Guide rollers or self aligning rollers may be considered as the last option.



Thanks and regards,

S.Ganesh

+91 9033481676 ■

Ganesh,

Thanks for pointing out the fire risk: rubbing had been automatically associate with abrasive wear.

This eliminates the proposed design on a safety issue. ■

you could try trimming the conveyor support uprights as shown in the images at the midpoint between return idlers to prevent contact from belt sag, or along the length to provide more clearance for belt misalignment. as you can see from the sketches this will provide clearance for the entire width of the return roller.

if maintaining alignment to the idler width is a problem then training idlers can be installed at appropriate intervals.

this modification can be done over time during scheduled maintenance or over a shorter period with the conveyor down. ■

Originally Posted by softedge

you could try trimming the conveyor support uprights as shown in the images at the midpoint between return idlers to prevent contact from belt sag, or along the length to provide more clearance for belt misalignment. as you can see from the sketches this will provide clearance for the entire width of the return roller.

if maintaining alignment to the idler width is a problem then training idlers can be installed at appropriate intervals.

this modification can be done over time during scheduled maintenance or over a shorter period with the conveyor down.

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Most ideas noted have merit. Without seeing the details, what about raising the vertical support attachment 1 inch or more to the stringer by drilling a new one or two holes in the vertical support and/or stringer to provide that much added clearance? Since the force is acting down drilling close to the top edge is less troublesome.

Most training idlers would not be a good idea due to their wondering until reaching a side guide roll. ■