Under-edge of Office Chair

The common circular knobs or adjustment levers under office chairs are primarily used to control the seat's height adjustment, with some also offering functions to adjust backrest elasticity, tilt angle, and lumbar support.

The most core function of the circular knob or adjustment lever at the bottom of an office chair is to control seat height adjustment. Its working principle is based on the mechanical structure of a gas spring (pneumatic rod): when the user rotates or pulls the adjustment lever, it manipulates the valve inside the gas spring, releasing or compressing the high-pressure nitrogen gas inside to achieve stepless height adjustment of the seat. This design allows users to quickly adjust the seat height according to the desk height or personal sitting posture needs, ensuring natural leg bending and flat feet on the ground, thereby maintaining correct sitting posture and reducing fatigue from prolonged sitting.

Some knobs at the bottom of office chairs also offer the function to adjust backrest elasticity and tilt angle. By rotating the knob, users can change the tension of the springs inside the backrest, thereby adjusting the support force of the backrest. For example, when leaning back, if the knob is set to the “high elasticity” position, the backrest will provide stronger resistance, suitable for scenarios requiring an upright sitting posture; if set to the “low elasticity” position, the backrest will tilt back more easily, suitable for short breaks or relaxation. Additionally, some designs allow users to fix the tilt angle of the backrest, preventing accidental rebound due to body movement during use.

The knobs at the bottom of high-end office chairs offer even richer functions, possibly integrating multi-dimensional adjustment capabilities. For example, some models' knobs can control the degree of lumbar support protrusion, adjusting the front-back position or height of the lumbar support through rotation to provide precise support for the lumbar spine and relieve pressure from prolonged sitting; other knobs are used to adjust the seat's pitch angle (i.e., the height difference between the front and back of the seat), allowing users to find the most comfortable sitting balance point whether working at a desk or reclining for rest. These functions are usually achieved through complex mechanical linkage structures and require fine-tuning with the help of the instruction manual.

It should be noted that the specific functions of the bottom knobs may vary among different brands and models of office chairs. Users should carefully read the product instruction manual before making adjustments to avoid damaging the chair or causing functional failures due to misoperation.