17–2 Flat- and Round-Belt Drives
Modern flat-belt drives consist of a strong elastic core surrounded by an elastomer;
these drives have distinct advantages over gear drives or V-belt drives. A flat-belt drive
has an efficiency of about 98 percent, which is about the same as for a gear drive. On the
other hand, the efficiency of a V-belt drive ranges from about 70 to 96 percent.1 Flat-belt
drives produce very little noise and absorb more torsional vibration from the system than
either V-belt or gear drives.
When an open-belt drive (Fig. 17–1a) is used, the contact angles are found to be