Pratissoli KF5M Serie Manuel D'utilisation Et D'entretien page 24

9.10 Transmission definition
To prevent irregular radial loads on the shaft and the relative
bearing, follow these directions:
a) Use pulleys with V‑belts with the size of the groove
required/recommended by the manufacturer of belt used.
In the absence of directions, follow Fig. 8 and the table in
Fig. 9.
Break
corners
Single groove Multiple groove
Fig. 8
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Fig. 7