In precision equipment such as industrial robot bases and wrists, crane slewing mechanisms, radar antenna turntables, medical equipment rotary platforms, and CNC rotary tables, bearings are often required to simultaneously withstand axial loads, radial loads, and tilting moments. Conventional solutions typically combine thrust bearings with radial bearings, significantly increasing axial dimensions and structural complexity.

 

NMT Precision Four-Point Contact Ball Bearings, with their unique Gothic arch raceway design, enable a single bearing to simultaneously withstand radial loads, bidirectional axial loads, and tilting moments, providing high-rigidity slewing support for precision transmission and industrial robots. This design philosophy of "one bearing replacing multiple combinations" results in simpler equipment structures, more compact axial space, and lighter overall weight.

 

The Gothic arch raceway is the core technology of NMT four-point contact ball bearings. Under no load or pure radial load, the balls form four-point contact with the inner and outer ring raceways; under pure axial load, the contact transitions to two-point contact—combining the functions of both single-row and double-row angular contact ball bearings. This unique contact state transition characteristic enables the bearing to maintain optimal load-carrying performance when facing combined loads with frequently changing load directions.

 

High rigidity is a standout advantage of NMT four-point contact ball bearings. Through precise design of the groove curvature radius coefficient and contact angle (typically 35° or 40°), NMT achieves an ideal balance between axial load capacity and radial load capacity. Precision-selected balls paired with superfinished raceways achieve micron-level matching, resulting in low friction torque and minimal temperature rise during operation, maintaining stable rotational accuracy and rigidity even under long-term continuous operation.

 

Compact structure is the practical value of NMT four-point contact ball bearings. Compared to double-row bearings, four-point contact ball bearings offer smaller axial space, higher limiting speeds, and smaller axial clearance. The separable structure facilitates installation—the bearing consists of a solid outer ring, separable inner rings, and ball-cage assemblies. During installation, the inner rings can be separated, allowing the balls and cage assembly to be inserted into the outer ring, after which the separated inner rings are fitted from both sides and secured with locking nuts.

 

NMT four-point contact ball bearings are manufactured from high-purity bearing alloy steel through precision forging and gradient heat treatment, achieving sufficient raceway surface hardness while maintaining core toughness, balancing wear resistance and impact resistance. High-precision cages accurately separate and guide rolling elements for smooth, low-noise operation. NMT has developed optimised lubrication solutions for four-point contact ball bearings, ensuring reliable operation under high loads and frequent start-stop conditions.

 

Core Product Advantages

Unique Gothic arch raceway design enables a single bearing to simultaneously withstand radial loads, bidirectional axial loads, and tilting moments—one bearing replacing multiple combinations;

 

Four-point contact under no load or pure radial load, transitioning to two-point contact under pure axial load—combining the functions of both single-row and double-row angular contact bearings;

 

Precise design of groove curvature radius coefficient and contact angle (35° or 40°) achieving an ideal balance between axial and radial load capacity;

 

Superfinished raceways paired with precision-graded balls for micron-level matching, low friction torque, minimal temperature rise, and stable accuracy during long-term continuous operation;

 

Smaller axial space, higher limiting speed, and smaller axial clearance compared to double-row bearings, adapting to compact spaces and high-speed conditions;

 

Separable structure for convenient installation and maintenance, with inner rings separable to simplify assembly;

 

High-purity alloy steel with gradient heat treatment, providing high raceway hardness and strong core toughness for wear and impact resistance;

 

Contact angles of 35° or 40° available, with open and sealed configurations to suit different operating conditions.

 

Typical Applications

Industrial robot bases and wrists—high-rigidity slewing support under combined loads; Crane slewing mechanisms—stable rotation under heavy eccentric loads; Radar antenna turntables and missile launchers—durable operation in all-weather outdoor conditions; Medical equipment rotary platforms (CT scanners, linear accelerators)—low-vibration, low-noise precision rotation; CNC rotary tables and indexing plates—high-rigidity precision indexing; Port machinery and marine slewing supports—long-term reliable service in salt-spray environments; Construction machinery rotary platforms—stable load-bearing under harsh conditions; Aerospace ground equipment turntables—reliable support under extreme conditions.

 

Quality Assurance

NMT four-point contact ball bearing quality assurance covers the entire process from raw materials to finished products. High-purity bearing alloy steel undergoes spectral analysis, inclusion rating, and grain size testing upon incoming inspection. Controlled-temperature forging refines grain structure. Gradient heat treatment with fully automatic process curve management ensures uniform raceway surface hardness and good core toughness.

 

Gothic arch raceways undergo precision grinding and superfinishing, with surface roughness consistently controlled to Ra ≤ 0.04μm, and ball-to-raceway matching accuracy reaching micron levels. Balls undergo multi-stage grinding and precision grading, with strictly controlled diameter variation within each bearing set. High-precision cages are precision-machined with accurate pocket dimensions and smooth surfaces for obstruction-free guidance.

 

Assembly of the separable structure takes place in clean environments—after separating the inner rings, the ball-cage assembly is inserted into the outer ring, then the separated inner rings are fitted from both sides. After assembly, locking nuts secure the bearing with precise axial clearance control. Finished products pass torque, vibration, rotational accuracy, and run-in tests, with complete data archived. Rust-preventive packaging ensures flawless delivery.

 

Product Range

Four-point contact ball bearing standard series—thin-section series (lightweight compact, suitable for robots and medical equipment), heavy-duty series (reinforced cross-section, suitable for cranes and construction machinery); Bore diameters from 16mm to over 650mm; Contact angles 35° or 40° available; Open, single-seal, and double-seal configurations available; Precision grades P0, P6, P5, P4; Clearance grades C2, CN, C3, and custom options.

 

Brand Strength

NMT has been dedicated to the research, development, and manufacturing of precision bearings for over a decade. As a core category within the NMT product portfolio, four-point contact ball bearings serve industrial robots, construction machinery, radar communications, medical equipment, CNC machinery, and other high-end equipment sectors with single-bearing combined-load capacity, high rigidity, and compact structure. The company operates complete precision machining production lines, professional testing laboratories, and an experienced technical team.

 

NMT four-point contact ball bearings deeply integrate the advantages of Gothic arch raceway design with precision manufacturing processes—from precise calculation of groove curvature radius coefficients to appropriate contact angle selection, from superfinished raceway processing to precision assembly of separable structures—continuously optimising across the three dimensions of high rigidity, compactness, and combined-load capacity. Bearings are the key to combined-load transmission systems. With professional capability and quality commitment, NMT provides trustworthy four-point contact ball bearing products for high-end equipment.