Office Chair Caster Replacement

Follow these steps to replace the casters on an office chair, ensuring safety and compatibility:

1. Identify the Caster Type Turn the chair upside down steadily and observe how the casters are attached to the chair legs:

• Snap-ring Casters: These have a circular groove at the top of the axle and make a clicking sound when pressed. They are commonly found on plastic chair legs.
• Threaded Casters: These have a visible external thread on the axle, similar to a screw structure, and are mostly used on metal chair legs.
• Special Cases: If the caster axle separates from the plastic part, use needle-nose pliers to grip the upper part of the ring as a fulcrum and pry it open.

2. Remove the Old Casters

• Snap-ring Casters: Insert a screwdriver or flat tool into the gap between the axle and the chair leg, gently pry the snap-ring position, and pull it out vertically after hearing a clicking sound.
• Threaded Casters: Use a 6-inch adjustable wrench to grip the base of the axle, rotate it counterclockwise at a 45-degree angle to the ground; if it is severely rusted, spray a small amount of WD-40 lubricant first.
• Emergency Handling: If the connection is too tight, use pliers to assist in removal, but avoid damaging the chair leg.

3. Install the New Casters

• Snap-ring Casters: Align the new caster with the chair leg socket and press it vertically until you hear a clicking sound, ensuring the snap-ring is fully embedded.
• Threaded Casters: Rotate clockwise until fully tightened, avoiding excessive force that may cause the thread to slip.
• Assisted Installation: If it doesn't go in, stand the chair up and sit on it, using your weight to press it in, but ensure the ground is level.

4. Test and Adjust

• Sliding Test: Push the chair on a tiled floor; the noise should be below 45 decibels, and it should roll continuously for 10 meters without jamming.
• Stability Check: Ensure the bottom of the gas lift is at least 2 cm above the ground, with a diameter error not exceeding ±0.5 cm, to prevent the chair from tilting.

Precautions

• Material Selection: For hard floors (wood/tile), choose PU casters to reduce scratches; for carpeted environments, choose nylon casters for better grip.
• Size Matching: The common insert rod diameter is Φ11 mm; an error exceeding 0.2 mm will result in unstable installation, requiring replacement with compatible casters.
• Emergency Handling: If the connection doesn't match, sand the metal insert rod or wrap it with Teflon tape to increase the diameter (for temporary use only).
• Tool Preparation: Snap-ring casters require no tools; threaded casters need a 6-inch wrench; it is recommended to wear gloves when removing rusted casters to prevent slipping.

Tip: If the casters frequently fall off or roll abnormally, it may be due to deformation of the chair leg or aging of the gas lift, requiring simultaneous inspection and replacement.