FLENDER gear units for hydrapulpers


The most important raw material for the paper industry is wood. Because of its nature, mainly softwood (spruce) is used in production. To turn this wood into the cellulose needed to manufacture paper takes several elaborate steps. Before producing mechanical pulp/cellulose, the logs must be debarked. A frequently used debarking process is drum debarking. In this method, the logs are debarked in huge drums (length 30 to 40 m and 3 to 4 m in diameter) by rubbing the circulating wood logs together. These big drums are usually driven by a 2- or 3-stage FLENDER helical gear unit with a modified housing upper part. Besides the helical version, Siemens also offer bevel helical gear units. Output torques from 5,800 to 230,000 Nm can be achieved.


  • Improved noise behavior through ground bevel gears, noise-absorbing housing and high contact ratio of the gear teeth

  • Increased service life of lubricants (oil) due to design with a low maximum oil temperature

  • Very strong output shafts and output bearings allow high external axial and radial forces to be accommodated on pulper drives with rotor connection.


  • Pulper section