Office Chair Fixed Base

The fixed base of an office chair is a core component that maintains the stability of the backrest angle and supports the human sitting posture. Its primary function is to lock the backrest angle through mechanical structures, ensuring the natural curvature of the lumbar spine.

Core Functions of the Fixed Base

As the "control center" of an office chair, the fixed base primarily serves two functions:

1. Angle Locking and Adjustment: Taking a four-position locking base as an example, its internal mechanical locking mechanism (such as gears, latches, or spring structures) enables graded fixation of the backrest tilt angle. Users can select different positions based on work scenarios (e.g., focused work, relaxation) to keep the backrest stable at specific angles, preventing angle shifts due to body movement.
2. Lumbar Support Protection: By fixing the backrest angle, the base helps users maintain the natural lordotic curvature of the lumbar spine. When the backrest angle matches the physiological curve of the human spine, it distributes sitting pressure and reduces the risk of lumbar muscle strain caused by prolonged sitting.

Typical Structural Features of the Fixed Base

Although detailed structural information is not provided in the reference materials, according to industry-standard designs, fixed bases typically include the following key components:

• Locking Mechanism: The core component, which may employ gear engagement, ratchet latches, or hydraulic damping technology. A four-position locking base achieves angle grading through preset slots or gear positions, allowing users to switch positions using a lever or knob.
• Load-Bearing Base: Connects the chair legs to the backrest and must be made of high-strength materials (such as steel or engineering plastics) to withstand human weight while distributing pressure through structural design to prevent local deformation.
• Angle Adjustment Range: The adjustment range of fixed bases is typically 90°-135°, covering scenarios from upright working to semi-reclined resting. Some high-end bases support stepless adjustment, enabling finer angle control through friction damping.

Difference Between Fixed and Dynamic Bases

It is important to distinguish between "fixed bases" and "dynamic bases":

• Fixed bases emphasize angle locking functionality and are suitable for scenarios requiring stable support (e.g., focused writing, drawing).
• Dynamic bases (such as synchronous tilt bases) allow the backrest and seat cushion to tilt in tandem, adapting to the body's natural movements, and are more suitable for scenarios requiring frequent posture changes.

Purchase Recommendations

When selecting a fixed base, focus on the following parameters:

• Number of Positions: Four or more positions provide more flexible angle options.
• Locking Stability: Test sit to check if angle switching is smooth and if there is no wobbling after locking.
• Material and Craftsmanship: Prioritize metal materials or high-strength plastics to ensure no deformation during long-term use.