Office Chair Swivel Base

The rotating 'disc' beneath an office chair, formally known as the base or swivel base, is the core support and adjustment mechanism of the office chair, integrating three core functions: horizontal rotation, backrest tilt adjustment, and load-bearing connection.

1. Horizontal Rotation

The base connects to the gas lift via a central shaft, enabling the seat (including cushion and backrest) to rotate horizontally around the axis of the gas lift. This design allows users to turn around to retrieve items, communicate with colleagues to the side or rear, or slightly adjust their angle facing the computer without moving the chair's feet, significantly enhancing office flexibility and efficiency. For example, in collaborative work scenarios, users can quickly switch communication partners through rotation, reducing the frequency of getting up and adjusting.

2. Backrest Tilt Adjustment

The base incorporates mechanical structures such as springs, dampers, or fiberglass springs internally, enabling backrest tilt functionality through the operation of a control lever or knob. Based on the tilt method, bases can be classified into three types:

• Back Tilt: Only the backrest tilts backward, suitable for scenarios requiring short breaks;
• Seat Tilt: Only the seat cushion tilts backward, dispersing pressure on the lower back;
• Synchronous Tilt: The backrest and seat cushion move synchronously in angular displacement, providing a more ergonomic natural lying position. For instance, the base of the Sihoo C500 second-generation ergonomic chair is specially designed to create a floating sensation when lying back, reducing physical strain.
  Users can lock the backrest tilt angle using the right-side control lever or adjust the rebound force via the knob at the bottom of the base to meet personalized needs.

3. Load-Bearing and Connection

The base serves as the hub for force transmission: its upper end connects to the seat frame, directly bearing the user's weight; its lower end fits over the top of the gas lift via a central hole or sleeve, transmitting the lifting function (driven by the nitrogen pressure difference inside the gas lift to extend or retract the piston rod) to the seat. This structure ensures stability during rotation, tilting, and lifting while distributing pressure and extending the chair's lifespan.

Structural Composition

The base consists of two parts:

• Control Mechanism: Includes the right-side control lever (responsible for lifting and backrest tilt locking) and a cylindrical knob at the bottom (adjusting backrest rebound force);
• Connection and Mechanical Structure: Comprises metal frames, shafts, springs, and other components, achieving stable functionality through precise assembly. Different brands and models of bases vary in design; for example, high-end models may adopt more complex synchronous tilt mechanisms or optimized materials to enhance comfort.