Relationship - Belt Rating & Counterweight
There is a direct relationship between belt rating and counterweight on most, but not all horizontal and singular sloped oriented belts.
The relationship can be confused when the belt geometry is undulating up and down, down and up, et al due to trying to maintain a minimum belt sag condition which may not occur at the beginning or end of the conveyor's geometry.
The operating belt rating of fabric belts is based on a 10:1 safety factor of the belt's breaking strength multiple over its maximum operating tension. There are many answers that depend on number of driven pulleys, ratio of power between driven pulleys, type of drive pulley lagging, wrap angles of belt on drive pulleys, et al. Assume a simple one drive and rubber lagging, where the ratio of maximum rated operating tension (T1 = belt rating/10) is a multiple of the counterweight tension (T2 = belt tension at counterweight; this will be close to the minimum belt sag tension required), and where T1/T2 = about 2:1 (depending on wrap angle and lagging friction factor); and where power is proportional to T1-T2= Tractive Driving Tension (TE).
You can now compute the direct relationship between belt rating and counterweight. ■
Re: Relation Between Belt Rating, Counter Wt & Belt Laying
Thank you Mr.Lawrence Nordell !
I am a maintenance engineer. The belt rating and counterweight are already fixed for the conveyor in which I need to replace the belt. Belt specification & elongation property, counter weight details are known.
I want to replace the full length of this belt as it is worn out.
I want to keep the elongation of the belt with in control.
I assume that elongation of the belt is welcomed if it is controlled one as the elongated length at the take up area will be used to remove weak joints or defective area of the belt in future. It will work as a buffer length and reduce the shut down time in case of new joints.
Given the pararmeters as earlier by me at starting of this thread, what may be the pulling force given on the belt at the end of replacing the full length of the belt? This is required to eliminate the laying slackness between the rollers.
We use chain block for this. We clamp one end and pull the other end. Should we use 1 tonne , 2 tonnes , 3 tonnes or 5 tonnes capacity chain block ?
What quantity of the force to be used to keep elongation of this conveyor under control? And how to ensure it? How to calculate this force?
I need the new belt to elongate but within 2% of total length.
Or do we need any additional parameters required to calculate it? ■
Relation between belt rating, counter wt & belt laying
I have to replace 630 metres of EP 1000/4 , 800 mm width HR grade belt. The counter weight is 3700 kgs. Belt elongation will be 2% as per the test certificate received along with the belt.
I need to replace the old belt by new one with this open end belt.
Before joining and start splicing of two ends to make it endless on structure of the conveyor, I need to ensure that there should be no looseness left in the newly layed belt and elongation would be with in 2% at control.
Now my question is, what is the capacity of chain block ( pulling devive ) I should use to ensure the above required criteria?
Is there any relation between counterweight or belt rating? ■