Since the aim of a hazelnut cracking machine is to break the shell and separate the kernel without damaging it, accurate speed and a steady load matter more in motor selection than raw power. The cracking rollers or discs usually turn at low speed through belts or a gearbox; motor power is set by the machine’s capacity and the number of cracking units.

DRG-802-6 0.55 kW 1000 rpm aluminium frame DRG three-phase motor – hazelnut cracking machine motor

Cracking unit and speed

In most plants, hazelnuts are first graded by size, and each size goes to a cracking unit set to its own gap. If the surface speed of the rollers changes, the share of uncracked nuts or of damaged kernels rises. The old speed and pulley ratio should therefore be kept when the motor is replaced; fitting a 3000 rpm motor in place of a 1500 rpm one spoils cracking quality unless the pulleys are changed.

Conditions that affect power

  • Hourly capacity and the number of units driven by the same motor
  • Shell hardness and moisture; undried hazelnuts need more effort
  • Sudden load increases if stones or foreign matter get in
  • Irregular feeding; when the hopper empties and suddenly refills, the motor load fluctuates

Other motors on the line

A cracking line also has grading screens, shell separation fans, elevators and conveyors. The aspirator fan used for shell separation has a different load characteristic from the cracking motor and is selected according to airflow. As shell dust can build up on the fan cover, regular cleaning should be planned during the season.

Preparing for the season

In the busy period after the harvest, a breakdown stops production. Before the season starts, bearings and belts should be checked, the nameplate of each critical motor recorded and, if needed, a spare of the same size obtained in advance. Selection is faster when the machine model, number of cracking units, capacity and existing motor nameplates are to hand.

Details on shelled-product cracking applications are on the nut cracking machine motors page; low and medium power models can be compared in the list of aluminium and cast iron frame motors.