The mechanism of an office chair is the most meaningful detail that can increase the workplace’ convenience to the user and protect against potential health problems associated with the incorrect sitting pose. Office workers often neglect office chair adjustments, and either do not use them, or use them incorrectly, due to the lack of knowledge about right body posture while sitting.
We would like to present a short list of systems used in office furniture.
Before starting, we suggest remembering that office chairs assume some adjustments to give optimal positions for "static" (see more in "Recommended static position") and "dynamic" posture.
Let us remind that a "dynamic" position is the right posture and support of the body, when the pelvis slightly moves even while sitting, by preventing such problems as "heavy legs", muscular aches, and other senses of discomfort thanks to improved blood flow.

We have analyzed chair structures according to their operation principles and can describe the main types and options.

Tilt Mechanism for office chair.

A tilt mechanism is used to incline the upper part of the chair. However, the angle between backrest and seat remains unchanged.
Such a system is typical for chairs with an upholstery where both parts are undivided.
Chairs with this tool are good for short-term sitting but are not suitable for use during a whole working day.
A tilt structure usually has several adaptations:
- seat height;
- locking/unlocking;
- adaptation to the user's weight.

This system is used in the following chairs — Aloma-A by Snug., Pilot High WA 05-46 by Johanson, Yopo EYP90-91 by Kano.

Synchronized Mechanism for office chair.

A synchronized mechanism is used to incline both parts of a chair simultaneously. Their move is simultaneous but inclinations are different. These angles have a certain ratio, usually, 1:2.5 (some manufacturers install a system with a ratio of 1:3.5, as, for instance, performed in the Lim 98 Padded chair by Kloeber). It means that while a seat inclines for 1°, the backrest inclines for 2.5° at the same time.
The main feature of this system is that all parts of the chair repeat pelvis movements both in "static" and "dynamic" postures.
The synchronized structure is good to use during the whole working day.
This system has several adaptations:
- seat height;
- locking/unlocking;
- adaptation to the user's weight.

The Mera Dimond chairs by Kloeber can be equipped with a synchronized structure.

Self Weight Mechanism for office Chair.

The self weight mechanism is another type of a synchronized system. The main feature is that it adapts to body weight by itself.
It is good for prolonged use at work. This system is simpler and better for any position.
Such a structure has one less lever in the design and, therefore, only two adaptations:
- seat height;
- locking/unlocking.

An example of such a system can be found in Moteo Mot89 by Kloeber, Open Up Midern Classic up133 by Kloeber, Black dot + ID mv102 by Sedus.

Asynchronous Mechanism for office chair.

The asynchronous mechanism helps to adapt all parts of the chair as you wish.
Such a system is convenient for “static” posture. However, the chair does not adapt to the body in “dynamics.”
This structure is suitable for prolonged use at work.
As a rule, the asynchronous system provides such adaptations as:
- seat height;
- seat incline;
- backrest incline.

Seat Slider Mechanism for office chair.

The self-explanatory name tells us that this tool is used to adjust the seat depth. This system is specified in the UNI EN1335 standard and necessary for chairs which are used by different people.
Such a structure can often be found in integration with a synchronized one but more often such adjustment serves as an additional option and can be implemented with almost any other structures.
The striking examples of such a mechanism are Nika by Snug., Vixen-A by Snug., almost all models by Kloeber and Sedus.

Forward Tilt Mechanism For Office Chair.

The traditional synchronized mechanism is used to tilt the seat up to 8-10° against the floor.
Due to an additional system, it is possible to incline the seat forward to -5°, and make the bend between the body and the upper surface of the thigh a little more than 90° .
In the "dynamics," blood circulation improves and prevents "heavy legs" or muscle rigidity.
This structure is usually built into chairs of the highest quality and can be optional in the other systems. To adjust the inclination, the chair has an additional control lever.

This structure is realized in Black dot air bd-125 by Sedus, Mera Dimond by Kloeber.