A mechanism for inserting coil springs (10) produced by multiple coil winding devices of a pocketed coil assembly machine (100) between fabrics (21, 22) for forming pockets enclosing the coil springs (10) is provided. The mechanism comprises belt conveyor mechanisms (200) with multiple parallel conveyor belts, which may be individually controlled. Each of the conveyor belts is associated with a respective one of the coil winding devices and is configured to receive coil springs (10) produced by the respective coil winding device. The mechanism further comprises a push mechanism (420) configured to push the coil springs (10) arranged on the conveyor belts, in a direction transversal to a conveying direction of the conveyor belts, between the fabrics and into a welding stage (500) of the pocketed spring assembly machine (100).