As the rotating joints of construction machinery (e.g., cranes, excavators), slewing bearings require comprehensive evaluation of mechanical parameters, operational conditions, and installation requirements. Below are five key dimensions:

?1. Load Types and Calculation?

• ?Axial Force (Fa)?: Vertical force acting on the rotation axis (e.g., boom weight).

• ?Radial Force (Fr)?: Horizontal force (e.g., wind or lateral load).

• ?Overturning Moment (M)?: Torque generated by eccentric loads, calculated based on maximum working radius.
  Formula Example: For single-row four-point contact ball bearings, Fa' = (1.225Fa + 2.676Fr) × fs (fs = safety factor, typically 1.45).

?2. Structural Type Selection?

• ?Single-Row Four-Point Contact Ball?: Suitable for small/medium equipment, handles multi-directional loads.

• ?Single-Row Crossed Roller?: 30% higher load capacity due to line contact, but requires precise installation.

• ?Three-Row Roller?: Ideal for ultra-large equipment, only axial force and moment need verification.

?3. Dynamic Operational Adaptation?

• ?Rotation Speed?: Above 5 rpm, dynamic lifespan and grease type (e.g., #2 extreme pressure lithium grease) must be considered.

• ?Cycle Count?: Continuous operation equipment must be checked per JB2300-1999 fatigue life standards.

?4. Installation and Maintenance?

• ?Bolt Preload?: 65%-70% of yield limit, with inspections every 400 hours.

• ?Chassis Rigidity?: Bearing stiffness depends on external structure; avoid deformation causing stress concentration.

?5. Safety Redundancy Design?

• ?Static Safety Factor?: fs = 1.45 for cranes, plus dynamic factors (e.g., wind load).

• ?Bolt Verification?: 8.8-grade bolts must stay within the load curve limits.