Office Chair Lower Nut

The nuts under office chairs vary in characteristics and operation methods depending on their types and uses, mainly falling into two categories: the large nuts beneath height-adjustable chairs and the nuts for office seat cushions.

Large Nuts beneath Height-Adjustable Chairs

• Function: As a crucial fastener connecting the gas lift cylinder to the base or seat, it achieves self-locking through the friction between threads, ensuring the gas lift cylinder is firmly fixed between the chair's load-bearing structures. Its tightening state directly affects the smoothness of chair height adjustment, the overall structural stability, and long-term safety.
• Location and Specifications: Located at the bottom of the gas lift cylinder or at the connection point with the base, it is usually the largest hexagonal or round nut. Specifications are not uniform, with common metric threads including M8, M10, etc.
• Operation Points:
  • Installation and Initial Tightening: Operate in sequence - first install the casters into the five-star base, then vertically place the gas lift cylinder (with the thick end facing down) into the center hole of the five-star base for preliminary fixation; next, install the base onto the seat using screws; finally, align the seat (along with the base) vertically with the upper end of the gas lift cylinder and insert it, and finally tighten it with the large nut from the bottom of the chair. When tightening, use an appropriate wrench and apply even force in a clockwise direction until fully locked.
  • Regular Inspection and Anti-Loosening Tightening: It is recommended to inspect once every quarter. Use your hand or a tool to gently try to turn the nut in the reverse (counterclockwise) direction. If it can turn, it means it has loosened, and it needs to be immediately re-tightened in a clockwise direction.
  • Relationship with Height Adjustment: Chair height adjustment is achieved by operating the height adjustment lever or knob on the side of the seat and has nothing to do with the large nut at the bottom. Do not mistakenly turn it.

Nuts for Office Seat Cushions

• Pre-installation Preparation: Prepare wrenches suitable for the nuts (such as Allen wrenches, Phillips screwdrivers, etc.), rubber gloves, and confirm that the nuts, bolts, washers, and other parts are complete and free from damage or deformation. For electric seats, unplug the power cord first; for manual seats, lay the seat down or fix it on a flat surface.
• Locating the Installation Position: For some seats, first remove the outer fabric or leather of the cushion to find the metal frame or plastic bracket beneath the cushion. The nut is usually installed in the pre-drilled hole (mostly round or square threaded holes) where the bracket connects to the cushion. Pass the bolt through the corresponding holes in the cushion and the bracket, ensuring the bolt is perpendicular to the holes.
• Nut Fixing Steps: Screw the nut onto the end of the bolt by hand for preliminary fixation. If there is a washer at the hole, first place the washer on the bolt and then install the nut; use an appropriate wrench to turn the nut clockwise, first lightly tighten it until the bolt does not loosen, and then gradually increase the force to tighten it, avoiding excessive force; after installation, gently press down on various parts of the cushion to check if the nut is loose. If there is any abnormal noise or displacement, re-tighten it or adjust the hole alignment.
• Precautions: Ensure that the thread specifications and lengths of the nut and bolt match; when dealing with electric adjustment mechanisms, avoid touching the internal wires and test the seat adjustment function after installation to ensure it is normal; for special brand seats, refer to the official manual or contact after-sales service.