Office Chair Bottom Diagram
The bottom of a normal office chair typically consists of three parts: chair legs, casters, and a gas lift, with some chairs also equipped with a base plate. Common styles include five-star base and bow-shaped base.
The five-star base is the most common structure in office chairs, usually made of metal (such as aluminum alloy or steel) or high-strength nylon, featuring a radial five-claw design. Its core advantage lies in its strong balance. The five-claw structure evenly distributes the user's weight, capable of supporting 80-150kg, suitable for the vast majority of users. The bottom is typically equipped with universal casters (mainly made of PU material). The type of caster is selected according to the usage scenario: hard floors (such as tiles or wooden floors) require soft casters (to reduce scratches and noise), while carpets require hard casters (to reduce rolling resistance). Five-star bases are commonly found in ergonomic chairs, gaming chairs, and other scenarios requiring flexible movement.
The bow-shaped base is formed by bending a metal frame into a bow shape, directly resting on the ground without casters. It has a sturdy structure but poor mobility. Its design features simplicity and durability, suitable for fixed scenarios such as conference chairs and staff chairs where frequent adjustments are not required. The load-bearing capacity of a bow-shaped base is related to its material. Metal bases can typically support over 100kg, but long-term use may lead to deformation due to metal fatigue.
Other special structures include:
- Four-claw structure: Used in some minimalist-style chairs, with slightly weaker stability than a five-star base, suitable for lightweight users or temporary usage scenarios.
- Hidden rotating tray: Equipped in high-end chairs, located between the chair legs and the gas lift, preventing dust from entering the lifting system and extending its service life.
- Casters with locking function: Used in medical and laboratory settings, fixing the chair's position through a brake mechanism to ensure operational safety.
The gas lift is the core component for adjusting the chair's height, filled with high-pressure gas and controlled by a lever for lifting and lowering. High-quality gas lifts must pass BIFMA certification (American National Standards Institute for Office Furniture) to ensure durability and safety. Poor-quality gas lifts may cause the chair to suddenly sink due to unstable air pressure, posing a safety hazard.
The base plate is commonly found in high-end chairs, integrating control modules for functions such as lifting, tilting, and rotation. It is mainly made of metal and needs to work closely with the gas lift to achieve stable adjustments. Some base plates are also equipped with explosion-proof steel plates to prevent metal fragments from flying in the event of a gas lift explosion, enhancing safety.
