Secondary shredders is the input material for this equipment, it is the product that has already been crushed on the Primary grinder. The task of the secondary grinder is to significantly reduce the size of the fraction after primary crushing. Secondary wood chippers can produce chips up to 20 - 50 mm. Secondary grinders of solid materials can give a fraction at the inlet up to 2 - 3 mm. The main task of secondary shredders is to prepare the material for obtaining a useful product. For example, for wood - wood chips for fuel briquettes. Secondary solids grinders can produce fine gravel or even sand for the production of concrete products.