sponsoredDefence Systems Wire Race Bearings Enable Precise Motion in Defence Systems

Modern defense systems and equipment — ranging from optronic components and radar systems to remotely operated weapon stations — place the highest demands on the reliability of their components. Wherever masses must be moved, tilting moments absorbed, and positions maintained with high precision — often under complex climatic conditions — the choice of bearing technology determines performance, service life, and ultimately operational safety.

One technology that has proven particularly reliable in this environment is the wire race bearing. For companies in the defense and security sector, it offers extensive possibilities in design, material selection, and system integration — while ensuring high load capacity, repeatable precision, and robustness.

Design Principle with Clear Application Advantages

The fundamental difference between a conventional roller bearing and a wire race bearing lies in the design of the raceways. In traditional bearing technologies, rolling elements run directly on hardened raceways integrated into the housing. In contrast, in a wire race bearing, balls or rollers roll on toughened, hardened race rings made of spring steel wire. These race rings are integrated into the surrounding structure but remain functionally independent from it.

This structural separation between housing and rolling element raceways provides a decisive advantage: mechanically highly stressed raceways can be directly integrated into lightweight structural materials. This enables:

• Free selection of materials for the surrounding structure
• Use of various surface treatment technologies depending on material
• High flexibility in integration within limited installation spaces

The rolling elements — balls or, in applications with high tilting moments, preferably rollers — distribute loads uniformly along the hardened race rings. The bearing cage ensures defined spacing, smooth running characteristics, and operational stability.

Since preload in wire race bearing systems can be individually adjusted, an optimal balance between stiffness and rotational resistance can always be defined.

Material Freedom as a Lever for System Performance

In demanding applications, the relationship between stiffness, rotational resistance, weight, and load capacity is a key design parameter. Wire race bearings allow the load-carrying structure to be manufactured from materials required by the application — ranging from steel and aluminum to stainless steels and fiber-reinforced composites.

For design engineers, this means:

• Weight reduction with high load capacity
• Optimized stiffness-to-mass ratio
• Adaptability to extreme temperature and corrosion conditions
• Seamless integration into complex system architectures

Because the raceways are made of toughened spring steel, their mechanical performance remains independent of the chosen housing material. For example, lightweight aluminum housings can be combined with high-strength steel gear components to form a complete slewing ring assembly.

Surface and Sealing Concepts for Extreme Environments

Military applications frequently involve simultaneous exposure to multiple stress factors: shock, vibration, temperature fluctuations, seawater, sand, and dust.

Wire race bearings offer the advantage that housing components can be specifically adapted to application requirements through targeted surface treatments. Functional coatings for increased hardness or corrosion protection can be applied to the housing without the need to coat the raceways themselves.

Furthermore, a wide range of sealing concepts can be integrated from the outset of the design process. Environmental seals, for example, can be accommodated in a space-saving manner within the housing structure.

With lubricants optimized for the specific application, maximum service life can be achieved — even under harsh operating conditions.

Geared Slewing Rings: Precision Under Load

Geared slewing rings are commonly used in gun turrets, radar antennas, and electro-optical platforms. The combination of wire race bearing technology with integrated internal or external gearing enables the transmission of high torques while maintaining low friction torque.

Shock and vibration resistance are addressed during the design phase through analytical evaluation of both the gearing and bearing elements.

Particularly in azimuth and elevation movements of safety-critical systems, the following properties are essential:

• High stiffness with compact design
• Repeatable positioning accuracy
• Adequate drive performance through adjustable rotational resistance
• Large central bore for integration of cables, fluid lines, and sensor systems

Application-Specific Design and Variant Diversity

Slewing ring assemblies are always designed application-specifically. In many projects, collaboration therefore begins at an early stage of system development.

Experience gained from numerous realized projects, combined with close coordination during the early design phase, significantly contributes to optimizing functionality, service life, and overall system performance.

Slewing rings can be realized from a quantity of one unit and are available in diameters ranging from 100 mm to 2,000 mm. Depending on application requirements, suitable bearing types are selected, including:

• Ball bearings
• Cross-roller bearings
• Angular contact ball bearings
• Angular contact roller bearings

Application-specific solutions can be engineered for operating temperatures from –50 °C to +90 °C and beyond.

Application Scenarios in Defense and Security Systems

Sensor platforms and optronic systems benefit from compact, lightweight slewing rings with high stiffness and uniform rotational torque. Smooth, jerk-free motion and precise positioning are essential for target acquisition, reconnaissance, and surveillance.

Radar systems impose high demands in terms of diameter, stiffness, and continuous operation. Slewing rings with diameters of up to 1,800 mm must ensure precise alignment even under wind loads, vibration, and temperature fluctuations. Dedicated sealing and lubrication concepts ensure long-term reliability.

Weapon carriers and turret systems require high shock resistance, vibration robustness, and secure absorption of tilting moments and torsional loads. Geared slewing rings based on wire race bearing technology combine robust power transmission with precise motion behavior.

In all of these systems, bearing quality directly influences overall operational safety and reliability.

Validation

For high-quality components, design engineering is only part of the task. Comprehensive testing and validation procedures are equally critical.

Vibration tests, thermal load testing including torque measurement, and test rigs capable of applying moment, axial, and radial loads enable realistic simulation of operational scenarios.

Analysis of torque behavior, temperature rise, wear, and stiffness changes supports evaluation of:

• Performance under operational conditions
• Field failure risks

For manufacturers and system integrators, this ensures planning reliability — from prototype phase through series approval.

Conclusio: Technological Foundation for High-Performance Defense Systems

Slewing rings based on wire race bearing technology are more than an alternative to conventional roller bearings. They represent a design platform combining material flexibility, integration capability, and optimized weight-to-performance ratios.

In defense applications where precision, robustness, and reliability under extreme conditions are mandatory, they form the foundation for innovative, compact, and durable rotational assemblies.

For the security and defense sector, this means maximum design freedom combined with optimal performance — a decisive prerequisite when engineering excellence meets operational defense requirements.

Further information on slewing rings in defence can be found at: https://www.franke-gmbh.com/industries/defense-technology/