Slewing rings are large-diameter anti-friction bearings which are designed to transmit axial and radial forces and simultaneously absorb the resulting tilting moments. Their high strength makes them eminently suitable for heavy-duty applications.
They are important connecting elements and so they are used in many different ways in a wide and diverse range of machines and plant equipment, such as in the extraction and processing of raw materials, specialised civil engineering, road construction, earthworks, production of construction materials, handling of materials or machine tool manufacture.
Design features of slewing rings
Slewing rings differ from ball bearings or roller bearings in that they are not fitted on a shaft or in a housing like these bearings but are instead axially integrated in the connection assembly by the bolted fitting of the bearing rings. Slewing rings are generally laid in a horizontal position, but they can sometimes be suspended or installed in a vertical position.
Slewing rings consist of an outer ring and one or two inner rings (depending on the design) and, in the majority of cases, a sealed, grease-lubricated raceway system.
The ball and roller races on the rings are made of alloyed tempering steel and are precision-machined and induction-hardened.
The raceway systems are supplied with an initial application of quality lubricant to meet the given performance requirements. The raceway systems have lubrication points (grease nipples) where lubrication (grease) can be reapplied, either manually or, for extra convenience, through the use of central lubrication units.
The seals are made as standard from NBR profiles (nitrile-butadiene rubber) and provide reliable protection for the raceway systems, keeping them free of debris and dirt and shielding them from spray and splashing water. They also perform the important function of keeping the lubricant in the raceway systems. Special sealing profiles or multiple systems are used to meet certain specifications in heavy-duty environments or in tough conditions involving mechanical stress. Sealing profiles can also be made out of materials with greater heat resistance like FKM/FPM (fluoro rubber / fluorocarbon rubber) for special high-temperature applications.
There are various other applications and cases of operation, however, such as in enclosed drive systems where the sealing is not required on one or both sides and the raceways are supplied with oil or lubricated through the oil circulation system in the equipment.
Slewing rings with toothing mostly come with straight teeth, but inclined teeth and custom toothing designs are also possible.
The toothing is finished to a standard or higher specification depending on the type of slewing ring and the requirements. The teeth can be supplied with a hardened finish to withstand heavy-duty demands and high moments of force.
The toothing quality, tolerance limits, tilting travel, resistance, concentricity, running accuracy and surface protection all depend on the demands placed on the slewing ring.
There are many standard slewing rings but the majority of them are tailored to meet specific requirements and are developed jointly with the customer in any given case.
There are generally three main types of slewing ring:
- Without teeth
- With internal teeth
- With external teeth
These three basic types are taken as a basis for other bearing designs which are optimised for a wide and diverse range of applications and fields of use.
We supply slewing rings in dimensions ranging from Ø 250 mm to Ø 5000 mm.
- Single-row axial ball bearing slewing rings without teeth
- Single-row axial ball bearing slewing rings with internal teeth
- Single-row axial ball bearing slewing rings with external teeth
- Double-row axial ball bearing slewing rings with internal teeth
- Double-row axial ball bearing slewing rings with external teeth
- Single-row axial roller bearing slewing rings with internal teeth
- Single-row axial roller bearing slewing rings with external teeth
- Triple-row axial roller bearing slewing rings with internal teeth
- Triple-row axial roller bearing slewing rings with external teeth