RD 700 slewing bearing

RD 700 Slewing Bearing – Hybrid Roller-Ball Solution for Ultra-Heavy Rotating Excavator

The RD 700 Slewing Bearing is engineered for extreme-load applications requiring both high load capacity and smooth rotational performance. This hybrid design combines an upper row of cylindrical rollers with a lower row of steel balls across 19 models spanning 3,550–6,700 mm diameter and 159–221 mm height. Available in external gear (121 prefix), internal gear (122 prefix), and non-geared (120 prefix) configurations, the product delivers optimized solutions for wind turbine yaw slewing bearing large diameter, container crane slewing ring, ship crane slewing bearing heavy duty, mining excavator slewing ring large diameter, port handling equipment slewing bearing, offshore platform crane slewing ring, and stacker reclaimer slewing bearing large applications where conventional bearing designs reach their performance limits.

Technical Specifications

The RD 700 121 series comprises five size classes, each engineered for specific load regimes:

Each class features independently optimized roller length-to-diameter ratios, ball diameters, ring cross-sections, and bolt patterns for its specific load regime.

Core Engineering Features

Roller + Ball Hybrid Design

The upper row utilizes cylindrical rollers with line contact, distributing loads across a wider contact path than point-contact balls. This reduces contact stress and extends fatigue life under heavy cyclic loading, carrying the majority of axial deadweight and tilting moments from off-center payloads.

The lower row employs steel balls providing smooth, low-torque rotation with inherent self-aligning capability. This row absorbs secondary axial loads and compensates for minor misalignments or structural deflections that could cause damaging edge loading on pure roller designs.

This complementary pairing enables the RD 700 slewing bearing to handle higher combined loads than double-row ball bearings of equivalent size while maintaining smoother rotation than pure roller bearings.

Three Gear Configurations

· External gear (121 prefix): Precision-hobbed teeth on the outer ring, most widely adopted for port cranes, wind turbine yaw systems, and mining equipment

· Internal gear (122 prefix): CNC-shaped teeth on the inner ring, protecting drive mechanisms from wave impact, debris, and extreme weather exposure

· Non-geared (120 prefix): For hydraulic cylinder drives, multiple pinions on separate drive rings, or friction drive systems

Zero-Failure Engineering

Every bearing undergoes rigorous quality control:

· Materials: Vacuum-degassed GCr15 bearing steel with controlled inclusion ratings; forged 42CrMo alloy steel rings quenched and tempered for core toughness

· Raceways: Induction-hardened to HRC 55–62, precision-ground after hardening with profilometer-verified surface finish

· Sealing: Heavy-duty multi-lip nitrile seals standard; labyrinth seals for mining dust; fluoroelastomer (FKM) seals for offshore salt-spray exposure

· Traceability: Full material certificates with heat number traceability, heat treatment records, and 100% dimensional inspection reports

Industry Applications

Wind Turbine Yaw Systems

Multi-megawatt wind turbines subject yaw bearings to continuous low-speed oscillation combined with high static loads from the rotor, nacelle, and drivetrain. The RD 700 series in the 3,550–5,300 mm range provides optimal balance: the roller row absorbs massive axial weight and tilting moments from 150-meter-plus rotors, while the ball row maintains low rotational torque even after extended stationary periods in cold conditions. External gear configurations engage multiple pinion drives for redundancy and anti-clearance capability.

Container & Mobile Harbour Cranes & Portal Cranes

Mobile harbour cranes (e.g., Liebherr LHM-type) and portal cranes impose enormous tilting moments during container handling at maximum outreach, where 40–65 ton payloads are suspended 60 meters from the bearing centerline. RD 700 bearings in the 4,000–6,000 mm range with class 36–50 rolling elements deliver required load ratings. Multiple pinion drives engaging the outer ring gear provide distributed torque and redundancy. The hybrid design ensures smoother slewing motion than pure roller equivalents, critical for container positioning accuracy during high-speed loading cycles.

Mining Excavators & Draglines

Electric mining shovels and walking draglines depend on slewing bearings at the rotating interface between the lower crawler frame and upper structure. Single bearings must support entire upper works assemblies exceeding 1,000 tons, with tilting moments peaking when fully loaded dippers are raised to maximum boom angle. RD 700 bearings in the 4,000–6,700 mm range with class 40–50 rolling elements handle these conditions. Internal gear configurations (122 prefix) protect slewing drive mechanisms from falling material and debris in abrasive, dust-laden open-pit environments.

Offshore Platform Cranes

Offshore platforms and FPSO vessels require pedestal cranes enduring continuous salt spray exposure, wave-induced dynamic loading, and extended maintenance intervals. RD 700 bearings in the 4,500–6,700 mm range with class 40–50 rolling elements are specified for these applications. Internal gear configurations allow slewing drives to be housed within pedestal columns—protected from direct wave impact and extreme weather. Enhanced corrosion protection includes multi-layer zinc/aluminum thermal spray coatings, FKM seals for chemical and UV resistance, and full material traceability supporting classification body certification requirements.

Certification

FAQ

Q: What distinguishes the RD 700 from pure roller or ball slewing bearings?

A: The hybrid configuration combines roller load capacity with ball rotational smoothness—essential for applications requiring both extreme loads and precision rotation, such as 100-meter hub height wind turbine yaw systems.

Q: Are RD 700 bearings interchangeable with existing equipment?

A: Yes. Despite the hybrid design, bolt circle diameters, ring heights, and gear data conform to industry specifications, enabling direct replacement without structural modifications. Complete CAD models are available for new-build integration.

Q: What delivery times should I expect?

A: In-stock products ship within 7–15 days. Custom configurations require 4–6 weeks, depending on complexity and specific sealing or coating requirements.

Contact Us

Need technical specifications for your application with RD 700 slewing bearing? Contact our engineering team at mia@hgb-bearing.com to discuss load calculations, mounting configurations, or request dimensional drawings for your project.