Office Chair Cannot Be Raised

The common causes and repair methods for an office chair that cannot be raised can be divided into three categories: gas spring issues, mechanical linkage problems, and other issues, as detailed below:

Gas Spring Issues

Failure Causes: The gas spring is the core component for raising and lowering the office chair. Its failure is usually caused by wear on the seal ring, nitrogen leakage, blockage from internal impurities, or locking due to transportation collisions. Aging of the seal ring leads to decreased airtightness, and nitrogen leakage results in insufficient pressure; impurities can block piston movement; and severe vibrations during transportation may lock the gas spring at its lowest position. Repair Methods:

1. Fault Diagnosis: Repeatedly press the lift control button to feel for any sticking or complete lack of resistance; listen for a hissing air leak or metal friction sound; check for wobbling or unusual noises at the connection between the base and the seat.
2. Safe Disassembly: Turn the chair upside down on a stable surface; if it can barely rise, raise it to its highest position; use a rubber mallet to gently tap the connection between the bottom of the gas spring and the chassis, then tap the top connection with the seat, using vibrations to loosen it.
3. Replace with a New Spring: Choose a gas spring with universal dimensions, safety certification (such as SGS, BIFMA), and a matching load-bearing capacity; insert the new spring into the center hole of the base, ensuring it goes all the way in, then press the seat vertically down until you hear a click or feel a tight fit to complete installation.

Mechanical Linkage Problems

Failure Causes: Displacement of the mechanical linkage or failure of the gas valve pin are common causes, such as the control handle detaching from the gas valve pin, or accumulation of grease or dust in the base obstructing the pin's rebound. Repair Methods:

1. Check Handle Connection: Turn the seat upside down to confirm whether the end of the control handle can touch the metal pin at the top of the gas spring; if misaligned, use a wrench to adjust the position of the base's fixing screws.
2. Increase Trigger Travel: If the handle is pressed all the way down but still cannot touch the pin, attach a hard spacer such as a coin or plastic sheet above the pin to compensate for wear gaps.
3. Lubricate and Clean: Spray a small amount of WD-40 or sewing machine oil into the gap of the pin, repeatedly press the handle several times until the pin rebounds smoothly.

Other Issues

1. Regulator Valve Failure: If the seat sinks weakly, try rotating the base adjustment button multiple times to clear any impurities that may be blocking the valve.
2. Loose Screws on the Five-Star Base: Check the screws on the five-star base (especially the hex bolts at the root of the swivel) for looseness; tightening them can improve lifting difficulties.
3. Metal Fatigue Fracture: Users weighing over 90kg should check for cracks at the attachment point of the casters; metal fatigue fractures often occur here.
4. Poor-Quality Hydraulic Oil: Low-priced products may use poor-quality hydraulic oil that congeals at low temperatures in winter, causing delayed lifting. Use a hairdryer to evenly heat the metal parts of the base (avoiding localized overheating); raising the temperature above 20°C can temporarily improve the situation.