(June 7, 2011)

NSK has developed a series of bearings designed to cope with the dirt, moisture, abrasion and high mechanical loads of agricultural machinery applications.

The company can offer both a standard range of products and customer-specific bearings that are tailored to the relevant operating conditions.



NSK's double-row taper roller bearing features an asymmetrical design.

One of the two rows of taper rollers uses longer rollers so that it can absorb especially high loads.

Shorter rollers were chosen for the other row to minimise frictional losses and any losses of energy.

The clearance is set using an annular spacer fitted between the two inner rings, meaning the component is ready to mount.

The housing design has also been optimised to make it straightforward to fit the bearing in the transmission, thanks to a specially designed flange outer ring.

In addition, NSK has developed special design features for other bearings with agricultural engineering in mind.

These include a cast housing for a harvester flange unit that is tailored to the surrounding structure.

Combined with an upstream flinger, a snug-fitting triple seal forms an effective barrier in adverse operating conditions.

The company has also developed a bespoke flanged bearing unit for a manufacturer of sowing systems.

This involved making adjustments to cater for higher load requirements; the load rating was increased by 30 per cent.

An additional flinger supports the seal.

This combination makes a long life possible in very dusty conditions.

It is partly thanks to this customised bearing that the manufacturer is now able to offer a machine that allows farmers to cultivate the soil and sow different crops in a single operation.

The flanged bearing unit is supplied with maximum grease packing for lifelong lubrication.

Similarly high demands are placed on bearings for disc harrows, which operate in direct contact with soil under high mechanical loads.

NSK offers various types of bearings for this application, which incorporate features such as a triple-lip nitrile rubber seal.

The seals are fixed to a steel plate using adhesive and are said to be highly effective.

The bearings are available with round and square bores and with cylindrical and spherical outer rings.

Flingers are a typical feature of bearings designed for agricultural machinery.

They expel contamination before it reaches the seal and thereby ease the strain on the downstream seal systems.

The flingers do not come into contact with the outer ring; the bearings are capable of the same maximum speeds as standard bearing inserts and are also dimensionally interchangeable.

Bearings with flingers are suitable for applications where a large amount of dirt is to be expected and in machinery that is cleaned using a pressure washer.

Triple-lip seals are another design feature common to bearings for agricultural machinery.

Bearing inserts with such seals have a longer life if the drive systems are exposed to a high level of contamination in the form of water or dust.

As their dimensions are identical, these bearings can be used to directly replace existing bearing inserts.

When selecting bearings for demanding areas of use, a bearing manufacturer, who is willing to work together with designers, can prove to be a real asset for agricultural machinery manufacturers, according to NSK.

The company added that time is an important factor because weaknesses often only emerge during the prototype and test phase.

Harvesting usually imposes a clear schedule on innovations and improvements; the new machines have to be ready for market by harvest time.

One manufacturer of mounted implements for agricultural machinery was working on developing a series of rotary swathers (windrowers), which are used to collect crops such as hay and straw.

Initial tests showed that the pulleys in the new series soon failed.

Action had to be taken, so the manufacturer turned to NSK for help.

The pulleys used are designed like a double-row, sealed, steep-angle ball bearing with a reinforced outer ring.

They are exposed to high mechanical loads and become heavily contaminated while working out in the fields.

Following a thorough analysis of the operating conditions, NSK suggested using pulleys with reinforced outer rings and a special seal.

The lubricant also had to be optimised.

Instead of standard grease, specially developed MA7 grease is now used, which extends the bearings' life by up to 10 per cent in adverse environments.

Owing to the tight schedule in place, the rotary swather manufacturer wanted prototypes and production models of the bespoke pulleys within a short space of time.

NSK was able to meet this requirement, as a flexible plant in Germany is responsible for the production of bespoke bearings.

This is where customised bearing solutions for special requirements are engineered and produced.

To ensure fast adjustment and production times, the engineers can draw on a range of existing design solutions, such as for greases, seals and cages.

The two-week test phase results were reported to be excellent, so the manufacturer approved the prototypes for mass production after just six weeks.

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