Planetary gearboxes for waste shredding machines

Edited by the Engineeringtalk editorial team Dec 28, 2000

Brevini's planetary gearboxes are playing a major role in helping to overcome the growing environmental problem of waste recycling as part of machines designed for shredding waste.

Brevini's planetary gearboxes are playing a major role in helping to overcome the growing environmental problem of waste recycling.

The gearboxes are providing the modularity, lightweight and compact performance required on a range of machines, designed for shredding waste, including domestic, tyres and medical equipment, and also for reclaiming operations.

The primary function of the shredders, and the one which explains their continuous growth curve, is volume reduction.

The latter is the new mantra in waste management, primarily because of the greater volumes of waste - up to 3 times more - that can be accommodated in landfill sites if it is undertaken.

There are many different types of shredders.

These include machines for use with car tyres, to provide by-products and fuel for power companies, and those for use with domestic waste, construction materials and also medical equipment where the various waste products are pulverised into reusable or safe by-products.

The shredders have other uses too.

They are employed in manufacturing reclaiming, a process which ensures the constant reuse of materials used (especially) in automotive and domestic products A typical gearbox installation for a shredder demands planetary drives in several different configurations.

These configurations can include one, two or three stage gearboxes mounted horizontally.

Brevini is able to provide both the modularity and the flexibility, in terms of capacities, ratios and mountings, to meet these demands.

The units normally employed are the Standard Series planetary gearboxes or, for larger machines, its high-torque PDL series.

Since most shredders require two elements that cut and shear material, two gearboxes, usually with the same power ratings, are required for each machine.

To obtain the proper speed and torque requirements from three stage planetary units an electric motor drive is usually specified.

This contrasts with single or double reduction Brevini gearboxes, which are hydraulically driven, usually by hydraulic motors supplied by Brevini's sister company SAMHydraulik.

The use of a hydraulic system provides an advantage over the electrical system since some of the shock load can be absorbed internally.

The usual speed range is 15-30 rpm and for hydraulically driven units the typical duty cycles include a continuous torque for 85% of the time and a maximum requirement for the remaining 15%.

In addition to supplying planetary gear units Brevini has also been requested to work with the shredder manufacturer on stub shaft designs and oil circulation.

The stub shaft has been made available by Brevini to adapt the female spline output shafts of the gearboxes to the driven shredder shaft.

The work on oil circulation is directed at power requirements that exceed the normal thermal ratings for the planetary boxes.

Both of these are initiatives that go beyond just supplying a gearbox and are very much in keeping with Brevini's ethos of involving itself in customer designs to provide all round benefits to both user and supplier.