Joint Bearing Characteristics and Applications

​

Joint bearing is a specialized sliding bearing, distinct from traditional rolling bearings due to their ability to enable multi-dimensional angular deflection. Composed mainly of an inner ring (inner spherical bushing) and an outer ring (outer spherical housing), their spherical contact surface allows flexible swinging or tilting within a specific angular range. Below is a simplified overview of their core characteristics and typical applications.​

I. Core Characteristics​

Designed for scenarios needing "angular compensation," joint bearing focus on flexibility, load capacity, and adaptability, with six key traits:​

1. Multi-directional Angular Movement​

This is their most critical feature: the spherical contact between inner and outer rings enables radial, axial, and angular composite deflection. Typical swing angles range from ±3° to ±20°. This capability compensates for installation errors, component deformation, or angular deviations during operation.​

2. High Load-Carrying Capacity​

The spherical contact provides a large stress-bearing area. Wear-resistant pairings—such as metal-to-metal (e.g., steel-bronze) or metal-to-composite (e.g., steel-PTFE fabric)—allow them to withstand radial loads, axial loads, or combined loads. Heavy-duty models can have a rated dynamic load of up to thousands newtons.​

3. Low Maintenance​

Most joint bearing includes a self-lubricating structure: outer rings may have pre-designed lubrication grooves/oil holes, or inner rings may be inlaid with solid grease or PTFE liners, eliminating frequent lubricant additions. Their simple structure (no rolling elements, unlike ball/roller bearings) reduces wear and failure points, lowering maintenance needs. ​

4. Harsh Environment Adaptability​

Housings can be sealed (e.g., with rubber seals) or made of corrosion-resistant materials (e.g., stainless steel, engineering plastics), resisting dust, sediment, and water splashes. They also tolerate moderate impact loads and vibrations, suiting harsh conditions like bumpy construction sites.​

5. Easy Installation & Adjustment​

Their angular compensation means strict coaxiality between inner and outer rings is not required during installation. This reduces precision demands, especially useful for assembling large components (e.g., robotic arms, bridge bearings) where high coaxiality is hard to achieve.​

6. Suitability for Low-Speed, Heavy-Load Use​

Primarily designed for "low-speed swinging" (usually <50 r/min), their spherical sliding friction is stable at low speeds, avoiding issues like "slippage" or "vibration noise" common in rolling bearings. This makes them ideal for heavy-load, low-movement-frequency scenarios. ​

II. Typical Applications​

Leveraging the above traits, joint bearing is widely used in fields needing angular compensation, low-speed heavy loads, or harsh environments, with five main application categories:​

1. Construction Machinery (Primary Use)​

Construction machinery faces severe vibrations, deformation, and angular changes during operation, making these bearings key transmission parts. In excavators, they connect the boom to the arm and the arm to the bucket, compensating for excavation-related swinging. In loaders, they link the rocker arm to the frame and support the bucket tilting mechanism, withstanding heavy loads and angular deviations. In cranes, they enable telescopic jib joints and connect luffing cylinders to frames, ensuring flexible jib rotation.​

2. Automation & Robotics​

Industrial robots (especially multi-joint models) need precise multi-dimensional movement, and these bearings form their "joint core." For multi-axis robotic arms, they connect large arms to small arms and small arms to end effectors (grippers), achieving ±10° to ±20° swing angles for flexibility. In automated production lines, they are used in conveyor steering joints and lifting platform hinges, compensating for minor operational deviations. ​

3. Transportation​

Vehicles, ships, and transit systems experience component rotation from road/sea bumps or track unevenness, and these bearings provide buffering and angular compensation. In cars, they connect suspension control arms to frames and steering tie rod hinges (e.g., MacPherson strut lower arms), boosting stability. In ships, they support propulsion shaft joints and deck machinery (e.g., anchor windlasses), resisting seawater corrosion and impacts. In rail transit, they enhance bogie shock absorption in subways/high-speed trains, compensating for track-induced vibrations.​

4. Aerospace (High Precision/Reliability)​

Aerospace equipment demands strict weight, temperature resistance, and reliability, so these bearings are used in key moving parts. In aircraft, they enable landing gear retraction and control system links (e.g., aileron/elevator joints), tolerating -50°C to 200°C temperature changes. In spacecraft, they support satellite antenna steering and rocket engine swing joints, requiring lubrication-free (or long-life lubrication) and vacuum-resistant performance.​

5. Other General Machinery​

In medical equipment, they are used in surgical robot joints and prosthetic connections, needing low noise and high precision. In textile machinery, they support loom heald frame swings and dyeing equipment guide rollers, adapting to low-speed heavy loads and humidity. In additional construction uses, they assist tower crane slewing bearings and concrete pump truck arm connections, withstanding ultra-heavy loads. ​

III. Key Differences vs. Rolling Bearings​

To clarify their role, here are the core differences between joint bearing and traditional rolling bearing (e.g., deep-groove ball bearings):​

• Movement Form: Joint bearing uses spherical sliding for multi-directional angular deflection; rolling bearings rely on rolling friction for unidirectional rotation (few support angular contact).​

• Load Type: Joint bearing handle combined radial/axial loads and heavy loads; rolling bearings focus on radial (deep-groove) or axial (thrust ball) loads.​

• Speed Adaptability: Joint bearing suits low speeds (<50 r/min); rolling bearings excel at high speeds (up to tens of thousands of r/min).​

• Core Advantages: Joint bearing offers strong angular compensation and impact resistance; rolling bearings have low friction and high-speed stability.​

• Typical Scenarios: Joint bearing is used in hinges, swings, and heavy-load setups; rolling bearings fit motor shafts, gearboxes, and high-speed rotating shafts.​