Tag Archive for: Excavator bearing

In the field of construction machinery, the quality and timely delivery of slewing rings directly affect the stable operation of host equipment. In February 2025, our company successfully completed a supply task for a CAT excavator slewing ring to a client in Europe. This case demonstrates our supply chain capability and professional understanding of the Four-Point Contact Ball Slewing Bearing.

The slewing ring supplied in this project is of the four-point contact ball type. This bearing features a single raceway design where each ball contacts the raceway at four distinct points, allowing it to simultaneously withstand axial loads, radial loads, and tilting moments. Compared to other designs, the four-point contact ball bearing offers higher load efficiency, a compact cross-section, and good impact resistance, making it particularly suitable for excavators that require frequent slewing and heavy-duty operation.

The client in this case was based in Europe and explicitly requested a four-point contact ball slewing bearing for their CAT excavator. After order confirmation, our company strictly controlled every stage of production, inspection, and packaging. The slewing rings were shipped in February 2025 via a dedicated Europe logistics route. Each unit underwent dimensional accuracy, rotational flexibility, hardness, and flaw detection tests to confirm compliance with CAT standards. Anti-corrosion treatment and reinforced packaging were applied for long-distance transportation.

Upon arrival in Europe, the slewing rings were installed and tested. The customer reported excellent performance in actual excavator operations, including low friction, high rigidity, and stable rotational accuracy, effectively reducing slewing noise and vibration. This case once again proves our company’s professional capability in critical components for construction machinery, from product selection and quality control to international logistics.

What is a Four Point Contact Ball Slewing Bearing?

A four point contact ball slewing bearing is a precision rotary component primarily composed of an inner ring, an outer ring, a single row of steel balls, a cage (or spacer), and sealing devices. Both the inner and outer rings can be manufactured as either integral or split structures. Integral rings offer higher rigidity, while split rings allow for easier adjustment; for split structures, bolts are used to connect the two halves before the product leaves the factory.

This type of slewing bearing generally includes a cage or spacer to separate the balls. However, a full-ball (cageless) structure is used when load requirements are relatively high. The full-ball design provides larger load capacity but comes with higher frictional resistance, which can potentially cause scratches on the surface layer of the steel balls.

The basic structure is available in three gear configurations: without gear, with external gear, or with internal gear. All configurations offer high static load capacity. As a product of LDB (Luoyang Longda), this bearing type is manufactured using materials including 42CrMo and 50Mn, with nitrile rubber seals provided as standard.

How Does a Four Point Contact Ball Slewing Bearing Work?

The working principle is based on the Gothic arch raceway geometry.

Contact points:

• Conventional bearings: ball contacts raceway at 2 points
• Four point contact bearing: ball contacts raceway at 4 points (2 on inner ring, 2 on outer ring)

Load engagement:

• Pure axial load in one direction → 2 of 4 contact points become active
• Reversed axial load → opposite pair of contact points engages
• Combined loads (axial + radial + tilting moment) → all 4 contact points share the load simultaneously

Key outcomes:

• A single-row bearing performs functions that would otherwise require two separate rows
• Consists of two seat rings (inner and outer)
• Compact structure and light weight
• Gothic arch raceway profile creates precise contact geometry for efficient load distribution

Key Features of Four Point Contact Ball Slewing Bearings

Design features:

• Single-row compact design – only two seat rings, light weight
• Four-point contact geometry – enables combined load handling (axial, radial, and tilting moment simultaneously)

Configuration options:

• Gear options: no gear, internal gear, or external gear
• Ring structure: integral (higher rigidity) or split (easier adjustment)
• Ball arrangement: caged (standard) or full-ball (higher load capacity, higher friction)

Performance specifications:

• High static load capacity
• Outer diameter range: 300 mm – 10,000 mm
• Ball diameter range: 30 mm – 75 mm
• Rated load range: 129 kN – 3,410 kN
• Fast delivery: 10–30 days for custom orders

LDB specific features:

• Materials: 42CrMo and 50Mn
• Seal type: Nitrile rubber
• Hardness:
  • Normalizing: 187-241 HB
  • Quenched and tempered: 229-269 HB
  • Raceway quenching: HRC 55-62
• Inner diameter range: 100 mm – 8,000 mm
• Warranty: 12 months

Main Types of Four Point Contact Ball Slewing Bearings

1. By gear configuration:

• No gear (plain) – for applications without gear engagement
• Internal gear – teeth on inner ring, suitable for compact drive designs
• External gear – teeth on outer ring, common in excavators, cranes, and turntables

2. By ring structure:

• Integral ring design – higher rigidity, for heavy-duty applications
• Split ring design – easier adjustment and maintenance; bolted together before shipment

3. By ball arrangement:

• Caged design – standard, with spacers or cages to reduce friction and prevent ball-to-ball contact
• Full-ball design – no cage or spacer; higher load capacity but increased friction and potential for scratches on steel ball surfaces

Core Advantages of Four Point Contact Ball Slewing Bearings

Performance advantages:

• Combined load capability – bears axial, radial, and tilting moment forces in a single row
• Bidirectional axial load support – no additional raceways required
• High static load capacity – ideal for heavy shock loads and intermittent rotation

Design advantages:

• Compact and lightweight – saves space, reduces overall machine weight
• Design flexibility – customizable gear type, ring structure, and ball arrangement
• Cost-effective – lower manufacturing and maintenance costs than double-row or cross-roller alternatives

Operational advantages:

• Long service life – optimized sealing and lubrication for harsh environments
• Fast customization – 10–30 day delivery for custom orders

LDB product advantages:

• Suitable for main engines requiring large axial load, high overturning moment, long service life, and continuous operation
• Sealing structure and internal fixator can be optimized based on working environment
• Both standard and non-standard models available
• Complete sets available (without gears, with external gears, with internal gears, or individual ring gears)
• Secure packaging: metal bracket or export-standard fumigation-free wooden box

Common Applications of Four Point Contact Ball Slewing Bearings

Construction and heavy machinery:

• Rotary conveyors
• Welding robots and manipulators
• Small and medium cranes
• Excavators (turntable applications)
• Aerial work platforms

Other industrial applications:

• Solar tracking systems
• Wind turbine yaw and pitch systems
• Industrial turntables and indexing tables
• Medical imaging equipment (CT scanners)
• Material handling equipment
• Radar and antenna rotators
• Packaging machinery

Best suited for:

• Applications demanding high axial load capacity
• Resistance to overturning moment
• Continuous operation with extended service life

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

Key selection factors:

Factor	Considerations
Load requirements	Axial, radial, and tilting moment (kN·m); LDB range: 129–3,410 kN
Dimensional constraints	Outer diameter (300–10,000 mm), inner diameter (100–8,000 mm), ball diameter (30–75 mm)
Gear configuration	No gear, internal gear, or external gear based on drive system
Ring structure	Integral (higher rigidity) or split (easier adjustment)
Ball arrangement	Caged (lower friction) or full-ball (higher load capacity, but higher friction and scratch risk)
Operating environment	Temperature, dust, moisture, chemicals; LDB uses nitrile rubber seals (customization available)
Material and hardness	42CrMo and 50Mn; raceway quenching hardness HRC 55-62
Precision requirements	Specify required tolerances
Delivery schedule	LDB standard: 10–30 days for custom orders
Warranty	LDB offers 12 months

Additional selection tips:

• For large axial loads and overturning moments with continuous operation → single-row four-point contact ball slewing bearing is highly recommended
• LDB can optimize sealing structure and internal fixator design based on your working environment
• Non-standard models available upon request
• Consider total cost of ownership (maintenance intervals + expected service life)

LDB ：Custom Four Point Contact Ball Slewing Bearings Manufacturer

Company profile:
LDB (Luoyang Longda) is a professional enterprise specializing in the production and sales of slewing bearings (slewing rings), slewing drives, and gear transmission devices, serving industries from construction machinery to renewable energy.

Product specifications:

Parameter	LDB Range / Value
Brand	LDB (Luoyang Longda)
Outer diameter	300 mm – 10,000 mm
Inner diameter	100 mm – 8,000 mm
Ball diameter	30 mm – 75 mm
Rated load	129 kN – 3,410 kN
Gear type	No gear, internal gear, external gear
Delivery lead time	10 – 30 days
Material	42CrMo, 50Mn
Seal type	Nitrile rubber
Rolling element	Steel ball
Normalizing hardness	187 HB – 241 HB
Quenched and tempered hardness	229 HB – 269 HB
Raceway quenching hardness	HRC 55 – 62
Warranty	12 months
Packaging	Metal bracket or export-standard fumigation-free wooden box

LDB product advantages:

• Suitable for main engines requiring large axial load, high overturning moment, long service life, and continuous operation
• Customizable sealing structure and internal fixator based on working environment
• Standard and non-standard models available
• Complete solutions (without gears, with external gears, with internal gears, or individual ring gears)
• Secure packaging for safe delivery

Why choose LDB?

• Experience: Years of expertise in slewing bearing design and manufacturing
• Quality: High-grade materials (42CrMo, 50Mn) with precision heat treatment and raceway hardening to HRC 55-62
• Customization: Full engineering support for non-standard models
• Speed: 10-30 day delivery for custom orders
• Warranty: 12 months on all products
• Global shipping: Reliable logistics network worldwide

Contact:
Whether you need a four point contact ball slewing bearing for an excavator turntable, crane, welding robot, rotary conveyor, or any other rotary application, LDB delivers custom-engineered solutions with fast lead times and dependable quality. Contact LDB today to discuss your specific requirements.