Fortschritt Erntemaschinen GmbH has developed a new rotary grass cutter. The main requirements were larger working widths and higher
driving speedsPossible applications for the rotary grass cutter 765 are all areas where large areas are mown and where the risk of bad weather must not endanger the production of silage or hay.

The rotary grass cutter 765 consists of two mower bars with seven oval rotary discs each. Both mower bars are fitted to cross arms and can be slewed hydraulically in a horizontal direction from operating to transport position. Thus the rotary grass cutter 765 can be transported on roads without difficulty.

TECHNICAL DATA

• Working width – 5.30 m
• Transport width – 3.30 m
• Weight – 960 kg

The main drive is normally supported in Y-bearing flanged units, often with conventional cast iron housings.
This bearing arrangement is subjected to heavy dynamic loads and therefore insensitivity to shock loads is an essential requirement of the housing.

For this bearing position, Fortschritt selected an SKF Y-TECH unit, consisting of a Y-bearing insert and a flanged composite housing.

Y-TECH bearing unit with flanged housings are injection moulded from glass fibre reinforced polymer. The embedded steel wire reinforcement ensures form and temperature stability. The housings are lightweight and very stable, their breaking loads far exceed the load carrying capacities of the inserted bearings.

The permissible operating temperature ranges between -40 °C and +120 -°C. The housings can tolerate temperature peaks up to 140 °C for short periods. The housings are resistant to corrosion and most aggressive media.

Y-TECH bearing units are fitted with multiple seals, the bearings are greased for life with a long-life grease and thus maintenance-free.

Fortschritt decided to use Y-TECH bearing units to support the main drive because of their technical advantages; the bearings have proved successful in practice.

The customer informed SKF: “In an accident resulting from damage by a foreign object, the cutter disc shaft as well as the Y-bearing were completely destroyed. The composite bearing housing FYK 507 did not suffer in the least and could be re-used after a new bearing had been fitted. A conventional cast housing FY 507 would most probably have broken in this accident.”

Rüdiger Sontheimer,

SKF Industrial Sales Division,

Schweinfurt, Germany