Why the drive matters on smooth passages
Smooth (reduction) roll mills are the most numerous machines in a flour mill; semolina and middlings are reduced to flour over several stages. The aim is to reduce particles with little heat and low starch damage, so the speed differential between the rolls must be low and stable. The PL22 smooth roll triple set is a three-pulley drive that delivers this low ratio with a 22-rib PL belt.
Why small belt slip matters
Because the ratio on a smooth passage is already low, even a few percent of belt slip changes it noticeably. When the belt loosens or the grooves wear:
- flour fineness fluctuates and sifter loads become unbalanced,
- friction and heat between the rolls increase,
- performance varies from passage to passage.
So measuring belt tension and checking grooves regularly is just as important on smooth roll mills as on break mills.
How to spot groove wear
Remove the belt and look at the groove flanks. Polished flanks, rounded groove edges or a belt that bottoms out in the groove mean the pulley is worn. A groove gauge gives the most reliable check. Running on worn pulleys makes new belts slip early as well.
Renewing the set together
When all three pulleys have the same groove depth, the belt seats equally on each and the ratio stays stable. Replacing the whole set therefore lasts longer than replacing one pulley. The pulleys take taper bushes; we ship them with bushes to suit your shafts.
