High-tech compost turning

If you are a homeowner who maintains yard waste in a compost pile, you know the pile periodically needs to be turned over to promote decomposition. But if you’re in the compost business, an occasional turn with a shovel or pitch fork just won’t do — you need an industrial sized machine. Moreover, the market for such machines has been growing and is expected to continue doing so. According to estimates by Eurostat, a European statistics agency, the annual accumulation of domestic refuse in the 25 countries of the European Union runs to 250 million tons — and the trend is rising.

Serving a growing trend
The Topturn X is a self-propelled machine for composting tree clippings, yard and forest waste, and similar materials. Designed and manufactured by Komptech, Frohnleiten, Austria, its ergonomic cabin offers 360° of visibility and is easily accessible without climbing any ladders: you enter directly from the ground through the front windshield, which also serves as a frameless door. For transport, the machine folds into a compact form that easily fits on a flat bed trailer and does not require a special hauling permit.

The Topturn X achieves a significantly higher compost quality than the traditional composting method and, with its high turning capacity and compact space needs, provides an efficient solution for domestic and garden-waste composting operations.

The muscle of the Topturn X is a large, hydraulically driven turning drum with a maximum working width of 5700 mm and a working height of up to 2800 mm.

The turning drum is driven by a compact hydraulic-mechanical drive from Bosch Rexroth. A two-stage Hydrotrac GFT planetary gearbox transmits power from a Bosch Rexroth A2 fixed-displacement motor directly to the body of the drum. Speed of the drum can be infinitely adjusted from 0 to 200 rpm. “This enables the driver to select the best adjustment for the drum drive so as to adapt to any working conditions, both in and also at the end of the clamp,” says Rudi Pretzler, Komptech’s managing director.

Depending on the length, the drum can eat its way through a row of material at up to 3500 m3/hr. “In this way we are able to ensure that the waste is thoroughly mixed,” continues Pretzler. “Thus, we achieve optimum conditions for the biological breakdown and conversion processes in the compost material.”

Gearing up for hydraulics
Depending on customer needs, Komptech offers the Topturn X with a wheeled or crawler track chassis. The wheeled version achieves travel speeds to 6 km/hr and offers flexible maneuvering on firm subsoil. It is fitted with four single wheel drives from Bosch Rexroth. Each complete drive, consisting of hydraulic motor and gearbox, is mounted within the wheel rim. The total engine capacity of 242 kW (330 hp) can be supplied either by Bosch Rexroth’s Type A2 hydraulic fixed-displacement motors or Type A6 variable-displacement motors, depending on customer requirements. In either case, each of the four motors drives a Hydrotrac GFT, three-stage planetary gearbox. The compact gearboxes multiply torque delivered to the wheel by the motor.

Each drive is connected to the vehicle frame via an integral support flange on the stationary gearbox housing. Wheels are driven through an integral flange on each gearbox’s rotating housing.

The gearboxes have case-hardened and ground planetary and sun gears for high strength and ductility, which enables them to tolerate shock loading without damage. A large internal ring gear, which drives the rotating housing, has nitrided teeth for long life.

In addition to serving as a torque multiplier, the four gearboxes also support the entire weight of the machine — about 14 tons — via tapered roller bearings. Each gearbox also contains an integral spring-loaded, multiple-disc parking brake.

For more information, contact the author at guenter.mikolasch@bo schrexroth.at, or visit www.boschrex roth-us.com.

Award-winning design

The Topturn X, designed and manufactured by Komptech, was awarded the world-renowned Industrial Design Excellence (IDEA) award presented by the Industrial Design Society of America (IDSA) for 2005.

The jury was unanimous in its verdict: Despite its size, the Topturn X is attractive, intelligent and ergonomic. In addition, it was commended on its elegance and the design of the driver’s cab, which features 360° vision. Aesthetics and robust functionalism are therefore not a contradiction in terms for this self-propelled, triangular compost turner. The machine is designed for turning and mixing organic waste, such as tree prunings, bio-waste and waste derived from agriculture and forestry, sludge, and contaminated soil for composting.

According to then-IDSA president Celso Santos, “Heavy machines can be graceful, intelligent and ergonomically correct. The Topturn Compost Turner goes beyond. It’s extremely elegant, and the idea to lower the cabin to the ground so that the operator may enter and then swivel back to the top, allowing an overview of 360º, is fantastic. This operation could be performed in any local theater with success!”