Brevini Riduttori has developed one, two, and three-stage high torque in-line gear units for car tyre shredding systems. The shredder has two main counter-rotating shafts on which the shredding elements called knives are attached. Each element is independently controlled by a gear unit, and since most shredders have two elements, two gear units - one for each shredding element - are needed. The two drive systems used (electrically or hydraulically driven) have the same impact in shredder design today. For this reason, gear units for this application must deliver high torque, be compact in size, be able to use both electric and hydraulic motors, and offer a wide range of transmission ratios.
Brevini Riduttori’s S Series high torque planetary gear units are suitable for all applications that require high torque and compact size on fixed industrial equipment such as shredders and also on self-propelled machines. Compared to traditional gearboxes, planetary gear units are between 40 and 60% lighter and more compact. With its many output versions, numerous input options, and a wide range of standard accessories, the S Series makes it possible to use Brevini planetary gear units with all types of motors.
Electrical motors are normally used with a three-stage planetary gear unit. To achieve the right speed and torque, an electric motor is chosen according to required power, which can range between 1150 and 1750rpm. Therefore, the gear unit is chosen to obtain an output speed of between 15 and 30 rpm, based on the motor’s maximum torque. Many machines have work cycles that vary depending on the application, which is why the best choice can be made by assuming that the required continuous torque will be 70% of the applied torque, and by using an application factor of 1.5 and sizing the gear unit for a minimum operation of 25,000 work hours.
Hydraulic motors are used with a one- or two-stage gear unit. Using a hydraulic system has the advantage of internally absorbing some of the shock load. In this case, too, the speed ranges from 15 to 30rpm, while the torque varies depending on the application. The gear unit must be able to work at a continuous torque speed and support the maximum torque transmitted by the motor.
Unlike electric motor systems, applications with a hydraulic motor have a work cycle that generally requires a continuous torque for 85% of the time and a maximum torque for the remaining 15%. These motors are also sized with an application factor of 1.5 and a minimum operation of 25,000 work hours.