Hello

I have a question about screw take up system and need help for calculation travel distance of screw take up.

Iam designing a shuttle conveyor with 42 m length.

According to attached pictures of cema standard, 2 tables submitted for travel distance of screw takeup. In first table, mentioned travel distance is 3 % of center to center for 75% of rated tension. And in second table it is 1.75% for center to center distance in 75% of rated tension and for polyester wrap. What's difference between these tables?

Also in rule of thumb calculation it is 1.5% of tail and head center to center distance.

Iam confused.  Which one is correct?

For 42 m c-c length, traveling distance of screw is 1260 mm or 630 mm ?

Thanks

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