Top pressure by belt
The guidance of the workpieces in Edgebanders is mainly provided by a Feed chain, which is coverd by workpiece-friendly plastic limbs and Rubber blocks. The pressure bridge with non-powered rubber rollers is used as counter pressure. In industrial machines are used double-V-belts instead of the rubber rollers. This v-belts are guided in grooved rollers mounted at the upper pressure. The rollers run on spring-loaded ball bearings. They press the belt on the Feed chain, for moving perfectly syncron to the feeding chain.
Guidance with belts is necessary if the feed motion would be decelerate for a snatch by the use of aggregates with high chip removal dimensions.
upper pressure by chain
There are even a few Edgebanders which feed the workpiece with a bottom feeding chain as well as an upper feeding chain, which holds the workpiece and supports the feed by beeing powered.