The chair mechanism, often shortened to ‘mech’, is the core component for every office chair. It controls the way the chair lifts and reclines and supports the user. Many task chair users don’t fully understand how these mechanisms or controls work and often don’t make the most of their chair’s capabilities to maximise their comfort.
Office chair manufacturers call these mechanisms different names so it can be confusing to figure out which one your office chair has. To help you out we’ve outlined below each of the mechanisms you’ll find in our office chairs and how they work:
The mechanism, sometimes called ‘single point tilt’, simply allows the whole office chair to tilt backwards around a single pivot point. The backrest angle is fixed and does not change. When the user reclines their knees rise so this mechanism is not recommended for intensive use.
The tilt mechanism can include the following adjustments using levers under the seat:
You’ll find a tilt mechanism on our Oslo operator chairs.
The synchronised mechanism, sometimes called ‘synchronous’, allows the backrest and seat to tilt backwards in a synchronised way, usually with a ratio of 1:2.5 (sometimes 1:2). i.e. reclining the seat by 1° means the backrest reclines by 2.5°. This means that the office chair responds to the user in an ergonomic manner, encouraging good posture so office task chairs with this mechanism suitable for intensive use.
The synchronised mechanism will normally include the following adjustments using levers under the seat:
You’ll find a lockable synchronised mechanism on our Vienna Lite, Verona and Modena task chairs from Formetiq. The mechanisms on Verona and Modena also include seat depth adjustment – the ability to slide the seat forward or backwards to suit your body.
The asynchronous or asynchro mechanism allows you to adjust the angle of the backrest and seat independently, helping you find the optimal static position of use. The asynchronous is a mechanism suitable for professional and intensive use.
The synchronised mechanism will normally include the following adjustments using levers under the seat:
You’ll find the asynchronous mechanism on our RH Mereo posture seating.
The body weight responsive mechanism, sometimes called ‘self-balance’ or ‘self-weight’, is synchronised but it adjusts itself to suit the users body weight so no tension adjustment is required. This mechanism is ideal for intensive use.
The body weight responsive mechanism will normally include the following adjustments using levers under the seat:
You’ll find the body weight responsive mechanism on the Vienna Premier task chairs from Formetiq.
The orthopaedic mechanism is synchronised but offers a full range, including forward tilt. Most synchronised mechanisms allow the seat to be reclined from 0° (parallel to floor) to around 8-10° backwards tilt. The orthopaedic mechanism allows the seat to be tilted forwards a few degrees (around -5°) to increase the angle between your torso and your thighs beyond 90°.
A forward sloping seat helps increase blood flow to your lower legs, helping to reduce muscle stiffness, and reduces lower back pressure by encouraging the forward leaning position. This forward tilt option can normally be turned on/off.
This orthopaedic option, with independent back angle adjustment, also allows you to set the start point of the synchronised mechanism, to adjust the backrest angle independently of the seat. This mechanism includes the following adjustments using levers under the seat:
You’ll find this mechanism on our Sitesse range of office posture chairs.