Excavator Slewing Bearings Shipped to Europe from LDB

In June 2025, LDB (Luoyang Longda) successfully delivered a customized slewing bearing solution to a European excavator manufacturer. The core component supplied was a four point contact ball slewing bearing, specifically engineered for the excavator’s turntable. This bearing type is ideal for such heavy machinery because a single raceway can simultaneously handle axial loads, radial loads, and tilting moments. The four point contact design ensures larger load capacity and higher rotational accuracy, which directly improves the excavator’s digging stability and slewing precision.

Unlike standard offerings from other suppliers, LDB provided a fully tailored solution for this European client. The four point contact ball slewing bearing was integrated with advanced monitoring, lubrication, and sealing systems. This significantly enhances reliability in harsh job site conditions and extends the bearing’s service life. By combining compact structure with high performance, LDB helped the customer reduce maintenance costs and optimize overall machine uptime, demonstrating our ability to deliver professional slewing ring solutions globally.

What is a Four Point Contact Ball Slewing Bearing?

A four point contact ball slewing bearing is a precision-engineered rotary component that utilizes a single raceway with a Gothic arch profile. Unlike conventional ball bearings where the balls contact the raceway at two points, this design allows each ball to make contact at four distinct points—two on the inner ring and two on the outer ring. This unique geometry enables the bearing to simultaneously accommodate axial loads from either direction, radial loads, and tilting moment loads within a single, compact row. It is widely regarded as one of the most efficient slewing bearing configurations for applications where space and weight are critical constraints.

Key features of Four Point Contact Ball Slewing Bearings

These bearings offer a distinctive set of engineering features that set them apart from other slewing ring types:

• Single-row compact design: Achieves high load capacity with minimal cross-sectional height and weight, reducing the overall machine envelope.
• Four-point contact geometry: The Gothic arch raceway creates four contact points per ball, enabling bidirectional axial load support without additional rows.
• High rigidity under tilting moment: Maintains rotational stability even when eccentric loads are applied, which is critical for cantilevered structures like excavator booms and crane jibs.
• Low friction operation: Optimized ball-raceway contact reduces torque resistance, allowing smoother rotation and lower energy consumption.
• Wide dimensional range: Available from 300 mm to 10,000 mm outer diameter, with ball diameters from 30 mm to 75 mm, covering a broad spectrum of machinery sizes.
• High load capacity: Rated loads range from 129 kN to 3,410 kN, suitable for light-duty to heavy-duty industrial applications.
• Flexible gear options: Can be supplied with no gear, internal gear, or external gear to match different drive configurations.
• Integration-ready design: Seamlessly compatible with advanced monitoring sensors, automatic lubrication systems, and multi-lip seals for harsh environments.

How does a Four Point Contact Ball Slewing Bearing work?

The working principle revolves around the Gothic arch raceway profile. In a conventional radial ball bearing, the raceway is a circular arc that contacts the ball at two points. In a four point contact bearing, each raceway is shaped like a Gothic arch—two opposing circular arcs that meet at a point. When assembled, the ball contacts the inner ring at two points and the outer ring at two points, totaling four contact points per ball.

Under pure axial load in one direction, two of the four contact points become active. When the axial load reverses, the opposite pair of contact points engages. Under combined loads (axial plus radial plus tilting moment), all four points may share the load simultaneously. This load distribution mechanism allows a single-row bearing to perform functions that would otherwise require two separate rows (e.g., a double-row ball bearing or a combination of radial and thrust bearings). The result is a bearing that provides high stiffness, precision rotation, and excellent moment load capacity in a fraction of the space.

Advantages of Four Point Contact Ball Slewing Bearings

Compared to other slewing bearing types (such as cross-roller bearings or double-row ball bearings), the four point contact design offers several distinct advantages:

• Space and weight savings: The single-row construction reduces axial height by 40–60% compared to double-row alternatives, enabling lighter and more compact machinery designs.
• Cost efficiency: Fewer components (one row of balls, simpler rings) translate to lower manufacturing costs and reduced material usage.
• Bidirectional axial load capability: Handles thrust loads from both directions without additional raceways or bearings.
• High moment load capacity: The four-point contact geometry provides inherent resistance to tilting moments, making it ideal for excavator turntables and crane slewing units.
• Lower starting and running torque: Reduced friction compared to cross-roller bearings allows smoother rotation, especially under heavy loads.
• Simplified mounting and maintenance: One-piece design with standard mounting holes reduces installation time and complexity.
• Extended service life potential: When equipped with advanced seals, proper lubrication, and monitoring systems, these bearings can achieve 50,000–100,000 operating hours in well-maintained applications.
• Fast delivery: With a standard lead time of 10–30 days, production and supply can be aligned with demanding project schedules.

Applications of Four Point Contact Ball Slewing Bearings

Due to their unique combination of compactness and load capacity, these bearings are found across a wide range of industries:

• Construction and heavy machinery: Excavator turntables, crane slewing rings, concrete pump turrets, aerial work platform rotations.
• Renewable energy: Wind turbine yaw and pitch bearings, solar tracker slewing drives.
• Industrial automation: Robotic manipulator bases, indexing tables, packaging machinery turntables.
• Medical equipment: Large CT scanner gantries, radiation therapy machine positioning rings.
• Material handling: Stacker-reclaimer slewing units, port crane turntables, conveyor swivels.
• Marine and offshore: Ship crane slewing bearings, offshore platform crane turntables.
• Defense and aerospace: Radar antenna rotators, missile launcher turntables, vehicle turret bearings.

Key factors when choosing a Four Point Contact Ball Slewing Bearing

Selecting the correct four point contact ball slewing bearing for a specific application requires careful evaluation of multiple parameters:

Factor	Considerations
Load requirements	Static and dynamic axial loads, radial loads, tilting moment (kN·m). Ensure rated load (129–3,410 kN) matches application demands.
Dimensional constraints	Outer diameter range (300–10,000 mm) and ball diameter (30–75 mm) must fit the available mounting space.
Rotational speed	Typical speeds are low (<10 rpm for large diameters, up to 50 rpm for small diameters). Higher speeds may require cross-roller designs.
Gear configuration	Choose no gear (for direct drive), internal gear, or external gear based on the drive system design.
Operating environment	Temperature range, humidity, dust/debris exposure, chemical exposure (corrosion resistance may require special coatings or stainless steel).
Lubrication method	Grease (standard), oil bath, or automatic centralized lubrication. Re-lubrication intervals depend on duty cycle.
Sealing requirements	Standard rubber lip seals for dust protection; heavy-duty multi-lip seals for water/dirt; labyrinth seals for extreme contamination.
Mounting structure	Bolt circle diameter, bolt size and grade, housing flatness (typically ≤0.05 mm tolerance), bolt preload specifications.
Precision and backlash	Standard precision for general applications; reduced backlash for positioning accuracy (e.g., robotics, radar).
Inspection and monitoring	Optional integrated sensors for wear detection, temperature, vibration, or rotation angle.
Delivery schedule	Confirm that the required lead time (standard 10–30 days) aligns with project milestones.

A properly sized bearing should have a static safety factor (fs) of 1.10–1.60 for normal rotating applications and 1.60–2.50 for heavy shock loads or critical safety applications.

LDB: Custom Four Point Contact Ball Slewing Bearings manufacturer

LDB (Luoyang Longda) is a professional enterprise specializing in the production and sales of slewing bearings (slewing rings), slew drives, and gear transmission devices. With years of engineering expertise, LDB has established itself as a reliable supplier of high-performance rotary components for industries ranging from construction machinery to renewable energy.

Within our product portfolio, the four point contact ball slewing bearing represents a core offering. This bearing type is designed for applications requiring compact dimensions, high load capacity, and the ability to withstand combined axial, radial, and tilting moment loads in a single row. LDB manufactures these bearings with strict quality control and offers extensive customization to meet specific customer requirements.

Our custom capabilities include:

Parameter	LDB Capability
Outer diameter	300 mm – 10,000 mm
Ball diameter	30 mm – 75 mm
Rated load	129 kN – 3,410 kN
Gear type	No gear, internal gear, or external gear
Delivery lead time	10 – 30 days