The data contained in this catalogue refer to oscillating motions or slow rotating movements.

It is, of course, possible to use large-diameter bearings for higher circumferential speed. For such requirements it is necessary to carry out special checks on the raceways and gears and to adapt these to the operating conditions if need be. Enquiries concerning such applications should include a description of the operating conditions as well as the customer‘s requirements.

If the bearing is to be installed with its axis in the horizontal position, we must be consulted beforehand.

Operating temperature

Standard design bearings are suitable for operating temperatures ranging from 248 K (– 25° C) to 333 K (+60° C). The various operating temperatures require suitable lubricants, see Lubrication and Maintenance.

For higher or lower operating temperatures and/or temperature differences between the outer and inner rings we must be advised beforehand so that checks can be carried out. Requirements regarding the mechanical properties of the ring material are of particular importance. In many cases, for instance, a minimum notch impact strength will be required for applications at sub-zero temperatures.

Classification / special conditions

Quite a number of applications as in offshore installations and ship deck cranes require classification. For this purpose, the respective classification agencies have produced a catalogue of requirements and specify acceptance of the bearing in accordance with that document.

In order to be able to take such specifications into account when preparing our offer, we need to kow the specifications in detail beforehand.

Seals

The seals provided in the bearing gaps prevent dust and small particles from directly entering the raceway and retain fresh lubricant in the bearing gaps. In this function, they have proven satisfactory under normal operating conditions for many years. With adequate relubrication, i.e. until a uniform collar of grease appears around the circumference of the bearing, their correct functioning will be assured.

In case of considerable dirt sediments appropriate covers should be provided at the companion structure.

As sealing materials are subject to ageing when exposed to a number of environmental conditions, seals require maintenance and, depending on their condition, may have to be replaced. Controlling: every 6 months.

Applications in a heavily dust-laden atmosphere, such as mechanical handling equipment for coal and ore, will require special seals. The RD 700 type series is, for instance, equipped with additional steel labyrinths at the upper bearing gaps, which have proven very satisfactory in open cast-mining. The steel labyrinth protects the seal against mechanical damage and it can be bolted in segments so that the space containing the grease can be cleaned, if necessary.

Bearings in ship deck and floating cranes are often exposed to splash and surge water. In such cases we use a special seal as shown in the following picture:



Installing this type of seal may increase the height of the bearing.

For the above applications it is preferable to use bearings with internal gears where the gear is protected by the surrounding structure.

Raceways

Plastic spacers are inserted between the rolling elements in the raceways. The bearings are supplied already greased. Penetration of aggressive materials into the raceways must be prevented on all accounts. Aggressive materials will alter the lubricating properties which will lead to corrosion in the raceways and damage the plastic spacers.

Special designs

Apart from the standard bearing series shown, we offer bearings tailored to specific operating conditions with regard to dimensions, running accuracies, bearing clearances and materials.

We also manufacture wire-race bearings. This bearing permits the use of non-ferrous metal rings and thus meets any special requirements regarding minimum weight, resistance to corrosion, etc.

Packing

Generally, large-diameter bearings will be wrapped in foil or a similar material for transport. The external bearing surfaces are protected against corrosion by means of Tectyl 502 C (oily) and by filling the raceways with lithiumbased grease.

The method of transport will determine the type of packing used (e.g. pallets, crates).

Standard packing will provide adequate protection for storage times of up to one year in enclosed, temperature-controlled areas.

Upon request, other preservation and packing methods can be provided for longer storage times (e.g. long-term packing for 5 years storage).