Gear Units for Shredders

Today truck and car tires are shredded for use by electric power and fuel companies. Typical shredder systems require planetary gear units in different configurations. For this type of application, Brevini Riduttori has developed one, two, and three-stage high torque in-line gear units.

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 the perfect solution 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 1750 rpm's. Therefore, the gear unit is chosen to obtain an output speed of between 15 and 30 rpm's, 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 30 rpm's, 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.

Offering improved performance in terms of life and quietness, the "S Series" range of Brevini Riduttori also possesses these main characteristics:

o 9 harmonically developed sizes, from 34,000 to 500,000 Nm of nominal torque
o In-line configuration with up to 4 reduction stages
o Right angle configuration with up to 4 reduction stages
o Output versions: female splined, hollow cylindrical for shaft mounting, male cylindrical or splined shaft
o Input versions with male input shaft, arrangements for electric and hydraulic motors, possibility of multidisc brakes
o A wide range of input and output standard accessories
o Possibility of integral solutions with gear units with a different technology.

Major dedicated investments, extremely reliable materials and processes, and the positive results of on-site final testing are proof of Brevini Riduttori's commitment and the outstanding quality of its "S Series" gear units. Thanks to company commitment and product quality, Brevini gear units are able to offer the market increasingly improved performance and more value for money.

PIV Drives and Brevini Riduttori
PIV Drives and Brevini Riduttori design and produce a complete range of drive solutions for the plastic and rubber processing industry, one of our strongest fields of application. Since 1980 more than 9000 single and twin screw extruder drives, rack and pinion drives and other drives are under successful operation world-wide. Among our customers are the most important companies of this sector.
Together with our customers we constantly improve our products and develop new products for the most various applications in the plastics and rubber industry. Our flexibility allows us to create individual drive solutions, customised to the relevant plant and its specific operational needs.

Brevini USA (
The company founded in the 1977 in Vernon Hills, IL., in the Chicago area where is still located, is the American subsidiary of Brevini Riduttori. Brevini's US headquarters includes a complete manufacturing center with an extensive inventory of units and service parts to support the North American market. The facilties include 25,000 sq. ft. of offices, manufacturing and warehousing for the Brevini product lines.


Luca Bortolani
Brevini Riduttori S.p.A
Tel.: +39 0522 9281
Fax. +39 0522 928300

For PIV Drives and German-speaking persons:

Bernard Rensinghoff
PIV Drives GmbH
Tel.: +49 (0)6172-102-648
Fax: +49 (0)6172-102-380

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