Caterpillar excavator slewing bearings shipped to Europe

In December 2025, LDB Slewing Bearing successfully delivered a customized four point contact ball slewing bearing to a European customer for use on a Caterpillar excavator. The customer required a high-performance slewing ring capable of handling heavy combined loads, harsh operating conditions, and demanding duty cycles.

LDB provided a fully tailored four point contact ball slewing bearing designed specifically for the excavator’s turntable application. Unlike standard solutions, LDB integrated advanced monitoring, lubrication, and sealing systems into the bearing, significantly enhancing reliability and extending service life. The four point contact design allowed the bearing to simultaneously support axial loads, radial loads, and tilting moments in a compact single-row configuration, making it ideal for the space-constrained excavator turntable.

Thanks to LDB’s global logistics network, the bearing was delivered on time to Europe in December 2025. Beyond the product itself, LDB’s expert services helped the customer optimize performance and reduce overall costs. This case demonstrates LDB’s capability as a professional supplier of high-quality four point contact ball slewing bearings for demanding heavy equipment applications worldwide.

What is a Four Point Contact Ball Slewing Bearing?

A four point contact ball slewing bearing is a single-row, angular contact ball bearing designed to accommodate simultaneous axial loads, radial loads, and tilting moments.

Unlike standard ball bearings where each ball contacts the raceway at two points, the raceway profile in this design—typically a Gothic arch or double-circular arc—creates four distinct contact points between each ball and the raceways. Two contact points are on the inner ring and two on the outer ring.

This unique geometry allows a single bearing to function like a combination of a thrust bearing and a radial bearing, eliminating the need for multiple bearing rows in many applications. The contact angle is usually 45 degrees, providing an optimal balance between axial and radial load capacity. When pure axial load is applied, all four contact points engage. Under tilting moment or radial load, the contact points redistribute dynamically, maintaining stability and rigidity.

Basic Structure of Four Point Contact Ball Slewing Bearing

The inner and outer rings are typically made of medium-carbon steel such as 42CrMo4 or 50Mn, quenched and tempered to achieve surface hardness of 55-62 HRC on the raceways while maintaining a tough core. One ring usually incorporates either internal or external gear teeth for drive integration, with gear modules typically ranging from 3 to 20 depending on load and drive torque requirements.

A single row of hardened chrome steel balls (typically GCr15 or equivalent) serves as the rolling elements. Ball diameters commonly range from 12.7 mm to 50.8 mm, with larger diameters used for higher load capacities.

The raceways are precision-ground Gothic arch profiles. The radius of each raceway arc is slightly larger than the ball radius, typically by a factor of 0.52 to 0.53 times the ball diameter. This geometric relationship ensures four distinct contact points while minimizing sliding friction.

To prevent ball-to-ball contact and reduce friction, either solid cages or individual spacers are used. Solid cages offer better guidance at higher rotational speeds, while spacers are more common in larger-diameter, slow-rotation applications.

Lip seals, often made of nitrile rubber (NBR) or fluorocarbon (FKM), are pressed into grooves on both rings to prevent ingress of contaminants such as dust, water, and abrasives. Grease nipples are installed at regular intervals around the ring circumference to allow periodic relubrication without disassembly.

Key Features of Four Point Contact Ball Slewing Bearing

The most distinctive feature is the ability to simultaneously support axial loads (both directions), radial loads, and tilting moments in a single row. Static axial load factors (fa) typically range from 1.0 to 1.5, while radial load factors (fr) range from 1.5 to 2.5 depending on the contact angle design.

Because only one row of balls is used, the overall height of the bearing is significantly lower than double-row or three-row designs, saving valuable axial space in equipment design.

The four-point contact configuration distributes loads across multiple points, increasing the load-carrying capacity relative to bearing volume. Static load ratings (C0) for common sizes range from several hundred kN to over 10,000 kN.

The optimized ball-to-raceway contact geometry results in lower friction compared to cross-roller or double-row designs. Starting torque can be as low as 0.02 to 0.05 times the bearing diameter in meters multiplied by the axial load in kN.

Unlike standard angular contact bearings that support axial load in only one direction, the four-point design handles axial thrust from either direction without requiring a second bearing. The bearing is also available with internal teeth, external teeth, or no teeth, allowing flexible integration with pinion drives, worm gears, or direct drive systems.

Applications of Four Point Contact Ball Slewing Bearing

In construction and material handling, these bearings are widely used in excavators (turntable connections between upper and lower frames), mobile cranes, tower cranes, concrete pumps, and aerial work platforms. In excavators specifically, these bearings must survive high shock loads, contamination from dust and debris, and often irregular lubrication schedules.

In renewable energy, they serve in wind turbine pitch and yaw systems, where the bearing must operate reliably for 20+ years with minimal maintenance, as well as solar tracking systems, where slow oscillation and exposure to weather demand good sealing and corrosion resistance.

In industrial automation, they are found in robotic positioning tables, palletizers, and rotary indexers, where precision and low runout (often below 0.05 mm) are critical.

Medical equipment such as large CT scanner gantries, patient positioning tables, and radiation therapy equipment also rely on these bearings, with additional requirements for quiet operation and smooth motion.

In defense and aerospace, they are used in radar antenna mounts, missile launcher turntables, and vehicle turrets, where reliability under extreme conditions is non-negotiable.

How to Select the Right Four Point Contact Ball Slewing Bearing?

Define the load spectrum. Gather the complete load history including axial load (Fa), radial load (Fr), and tilting moment (Mk). For rotating applications, also note rotational speed and duty cycle.

Calculate the equivalent static load. Use the formula: Foa = Fa + (2.05 × Fr) + (4.05 × Mk / DL), where DL is the ball pitch circle diameter in meters. The safety factor S0 = C0 / Foa should be at least 1.5 for dynamic applications.

Select gear type and module. Choose internal or external gearing based on your drive layout. Gear module typically ranges from 3 to 12 for construction equipment.

Define the mounting interface. Ensure bolt circle diameter, bolt size and pattern match your flange. Flange flatness should be within 0.05 mm per meter.

Specify clearance and preload. Choose normal clearance for most applications, reduced clearance for higher rigidity, or preload for zero-play requirements.

Choose sealing and lubrication. Select single lip seals for clean environments, double lip for dusty conditions, or labyrinth for extreme contamination. Use lithium-complex grease for -20°C to +120°C range.

Evaluate corrosion protection. For outdoor or marine applications, consider zinc phosphate coating, epoxy paint, or stainless steel rings depending on severity.

Validate with supplier support. Share your load data and operating conditions with your bearing supplier for final verification.

LDB: High Quality Four Point Contact Ball Slewing Bearing Supplier

LDB Slewing Bearing is a specialized enterprise focused on the design, development, manufacture, and sales of precision slewing bearings and precision slewing drives. Unlike mass producers who offer only standardized catalog products, LDB positions itself as an engineering partner capable of delivering fully customized four point contact ball slewing bearings tailored to specific application requirements.

When you choose LDB, you are not just buying a bearing—you are gaining a reliable engineering partner. Our global logistics network guarantees on-time delivery to Europe and beyond, while our expert technical support helps you optimize performance and reduce costs. Whether you need a standard four point contact ball slewing bearing or a fully integrated solution, LDB delivers quality, precision, and value.

Contact LDB today for your next project.