The core rotating parts of excavator slewing platforms, wind turbine yaw and pitch systems, radar turntables, large automatic rotary worktables and small port slewing equipment need to bear radial forces, bidirectional axial forces and tilting moments simultaneously. Conventional paired angular contact ball bearings require complex installation and occupy more space. A single set of four-point contact ball bearings can withstand three types of combined loads, making them the preferred option for compact rotating mechanisms. Bearings operate under long-term harsh conditions: low-speed reciprocating swing, alternating tilting moments, continuously changing load directions, outdoor dust and rain erosion, intermittent start-stop cycles and risk of creep during long static standby. Ordinary four-point contact bearings suffer insufficient raceway contour accuracy and difficult preload control. Local raceway pitting and continuous increase of rotary clearance easily occur under long-term swinging, resulting in shaking of rotating mechanisms and decreased positioning accuracy, which may seriously threaten equipment operation safety.

Focusing on R&D of rotary bearings for combined loads, Japan NMT launches four-point contact ball bearing series to solve industry pain points of traditional models including insufficient machining precision of Gothic arch raceway contour, local stress concentration under swinging conditions, weak sealing protection and large clearance variation after long-term operation. Adopting optimized Gothic arch double-arc raceway design, combined with five core upgrades including high-purity bearing steel, high-precision graded steel balls, high-strength solid cages, precise clearance/preload matching design and multi-layer composite seals, a single bearing independently bears radial, bidirectional axial and tilting moment loads without paired DB/DF assembly. Widely used in construction machinery slewing mechanisms, wind power equipment, radar equipment and automatic turntables, the bearings optimize contact stress distribution, reduce fatigue damage under reciprocating swing and maintain stable rotary performance for a long time.

Core Product Advantages

1. Single bearing supports three types of combined loads with highly compact structure: Four-point contact Gothic arch raceway structure enables one bearing to carry radial loads, bidirectional axial loads and tilting moments. No paired bearing arrangement is required, greatly saving axial and radial installation space and simplifying overall machine layout.

2. Adaptable to low-speed reciprocating swing and resistant to alternating tilting moments: Optimized specially for rotary and swing mechanisms, capable of sustaining tilting moments with constantly changing directions, ideal for equipment with continuous angle adjustment such as excavator slewing systems and wind turbine pitch systems, mitigating local contact fatigue damage.

3. Precision Gothic arch raceway for balanced contact stress: Double-arc Gothic arch raceway undergoes precision grinding to optimize ball contact tracks, avoid stress concentration, lower risks of local pitting under reciprocating swing and extend service life of raceways.

4. Multiple clearance options and support for preloaded assembly: Standard clearance, minimal clearance and preload-configurable specifications are available. Minimal clearance variants suppress rotary shaking for precision turntables; standard clearance absorbs slight deformation for general construction machinery applications.

5. Optional reinforced sealing adapting to harsh outdoor environments: Basic open type for clean indoor lubrication conditions; double-layer rubber seals block dust, rainwater and moisture ingress, meeting outdoor protection requirements of wind power and construction machinery.

Application Scenarios

Slewing support bearings for small excavators and special construction machinery; yaw bearings and pitch bearings for wind turbines; rotary bases for radar and optoelectronic tracking equipment; large rotary worktables on automatic production lines; small port slewing cranes and material turnover mechanisms; supporting positions of precision rotary platforms for medical devices and test equipment.

Precision Quality Assurance

NMT four-point contact ball bearings are manufactured strictly in accordance with Japanese standards for precision rotary bearings. Raw materials are inspected via flaw detection. Tests including reciprocating swing fatigue test, tilting moment durability test, dust & waterproof sealing test, long-term clearance stability test and neutral salt spray corrosion test are carried out. Featuring stable combined load capacity, uniform rotary resistance and controllable clearance, the bearings fully adapt to low-speed reciprocating rotary conditions with complex combined loads for wind power equipment, construction machinery and automatic turntables.

Product Range

QJ series four-point contact ball bearings; solid brass cages as standard; open type and double sealed type; standard clearance & minimal clearance optional; available as single units or matched sets; complete metric standard sizes, customized medium & large non-standard sizes supported.

Brand Strength

Japan NMT focuses on R&D and manufacturing of rotary bearings for combined loads, specializing in core technologies including Gothic arch raceway profile optimization, stress simulation under swing conditions, long-life sealing structures and precise clearance control. Supported by ultra-precision machining lines and rotary load simulation laboratories, NMT solves common industry pain points such as local pitting, rotary shaking and water/dust ingress through seals of four-point contact bearings used in wind power and construction machinery, supplying compact tilting-moment-resistant four-point contact ball bearing solutions for global machinery manufacturers.