Swing mechanisms play one of the leading roles in design of computer chairs. It is up to them adjust the sitting, to sit in chair was comfortable long hours all over. Opens the list of mechanisms so-called «piastre», used in simplest models of inexpensive chairs.

Piastre

Piastre mechanism allows you to adjust chair exclusively in height. It is a block with gas lift control lever (lifting mechanism with gas spring). By pressing the lever, valve opens in the gas lift, as a result of which the piston moves and comfortable seat height is adjusted.

Piastre mechanism only adjusts height of the seat.

Piastre mechanism does not provide for any other adjustments, except for the height position. As a rule, it is used in low-cost models of office chairs for staff and visitors.

Pros:

  • simple design;
  • high reliability;
  • cheapness.

Cons:

  • minimum available adjustments (only height adjustment);
  • armchairs with piastre mechanism do not provide proper comfort if you have to sit at computer for a long time.
Piastres office chairs

Permanent contact

Along with piastre in inexpensive chairs, there is a permanent contact mechanism. To the height adjustment of the seat, it adds seating depth and backrest deflection with free play.

Simple and inexpensive permanent-contact mechanism allows you to adjust height, inclination and seating depth.

Permanent-contact allows swinging within allowable deflection of the back. Mechanism is based on elastic spring that allows back of the chair to be pressed against back of the seated person. In free position, backrest is slightly tilted forward under action of the spring. As soon as person sits down in chair and reclines in it, the spring is compressed, back deflects under the weight of user and remains firmly pressed to the back. Due to presence of constant support, back muscles get tired less when sitting in chair for a long time.

Pros:

  • height, seating depth and back tilt adjustments;
  • simplicity of design;
  • high reliability;
  • cheapness.

Cons:

  • there is no way to adjust the stiffness of back deflection.
Permanent Contact Office Chairs

Spring-screw (freestyle)

Spring-screw mechanisms (freestyle) have similar principle of operation. They also have an elastic spring, additionally placed in plastic casing. The difference is that this mechanism allows you to adjust the degree of compression of the spring - by changing it, you can influence force that is necessary to deflect the backrest.

Freestyle mechanism offers ability to adjust compression ratio of the spring.

When twisting a special plastic “knob”, spring in design of freestyle mechanism is reduced, giving rigidity to inclination of the back, and when unscrewed, it is released, making the inclination easier. In general, backrest deflects depending on the force applied by user. In some instances of office chairs with spring-screw mechanism, several adjustment screws may be provided, which are responsible not only for back deflection, but also for adjusting the height, as well as distance from the seat.

Pros:

  • height and hardness adjustment of the backrest;
  • high reliability;
  • versatility of application;
  • aesthetic appearance.

Cons:

  • few adjustments available.
Office chairs with freestyle mechanism

Top gun (tilt and deep tilt)

Perhaps the most widespread in computer chairs is the top gun mechanism in two varieties - tilt and deep tilt. Top gun involves rigid connection of backrest with the seat, which does not have independent adjustments. By acting on lever of the mechanism up and down, the chair is raised or lowered, to the right and left, it activates the swing mechanism. Also in this mechanism there is often an adjusting screw to adjust degree of swinging rigidity depending on weight of the seated person.

Classic top gun is on the left, the deep tilt mechanism is on the right in picture.

Deep tilt differs from classic tilt by presence of separate lever responsible for swinging and fixing the chair in working position. Moreover, you can swing in chairs with deep tilt mechanism much more strongly - in such models it is allowed to lean back very far and practically lie down.

Pros:

  • adjustable swing height and stiffness;
  • fixing chair in working vertical position;
  • convenient and flexible adjustment to the user's weight.

Cons:

  • when chair is fully tilted, person’s feet do not reach the floor.
Interesting fact. The problem with fact that when leaning back in the extreme position, feet do not reach the floor, is solved in mechanisms with an offset axis. If it is located closer to the edge of chair, feet, regardless of inclination, are on the floor continuously. But usually in top gun swing mechanisms, axis is located in the middle of chair.
Office chairs with tilt mechanism

Multiblock

All the advantages of the top gun were absorbed by multiblock swing mechanism. Moreover, it provides number of additional settings: back of the chair can be fixed in four or five intermediate tilt positions, and during the swing it is allowed to adjust the force of chair deflection and swing stiffness.

In chairs with multiblock swing mechanism, maximum of various adjustments is provided.

Multiblock mechanism provides smoother swing, incl. with large amplitude. Backrest angle is adjustable over wide range from 0° to 135°. And in some models, you can even transfer the backrest to semi-recumbent and recumbent position, while balancing chair does not allow rider to tip over.

Computer chairs with multiblock swing mechanism are often equipped with an “anti-shock” system, which prevents back from deviating sharply back when landing and prevents shocks to the user’s rider’s back when the body position deviates forward. Backrest smoothly returns to its working position, regardless of selected swing mode.

There are several varieties of multiblock swing mechanism:

  • Offset axis multiblock - eliminates disadvantages of centered rotation axis. In particular, it prevents feet from lifting off the floor when leaning back strongly. The axis shifted to the front edge of chair allows feet to be on the floor continuously, and sitting with constant support on feet is physiologically correct body position.
  • Synchro mechanism is an advanced subtype of multiblock with movable connection between back and seat. Moreover, it is configured so that the back, when tilted, deviates twice as far as the seat. This proportion ensures correct fit. Chairs with synchro-mechanism are additionally equipped with load adjustment for personalized weight adjustment in order to ensure maximum unloading of the spine. Such mechanisms are used in top computer chairs.
  • Asynchronous mechanism provides maximum freedom in adjusting relative position of backrest and seat. It provides their self adjustment and repeats movements of the body of the rider. In other words, when chair back swings, the seat remains stationary and vice versa - by changing the angle of the seat, the back retains its position. Asynchronous mechanism is controlled by three levers. It is found in flagship models of chairs.
Synchro mechanism allows you to tilt backrest relative to the seat in proportions of 2:1, which ensures the most correct fit.

Swing mechanism of multiblock is characterized by solid pluses. No wonder it is used in models of the highest average rank and premium level. And this mechanism does not have any significant disadvantages.

Office chairs with multiblock mechanism

Anyfix and multifix

anyfix and multifix mechanics are roughly in same price league as top guns. But their competitive advantage is ability to fix the back of the chair in any intermediate position. The differences between these two options lie in fact that anyfix adjusts backrest angle and height using two levers on sides, and multifix has three adjusting tabs that are responsible for lifting, tilting the backrest relative to the seat and swinging the chair.

Backrest in armchairs with anyfix and multifix swing mechanisms can be fixed in any intermediate position.

Anyfix swing mechanism is used in mid-range gaming chairs and for boss models. Multifix - usually found in office "director's" chairs and models for staff.

Pros:

  • fixing backrest in any intermediate position;
  • flexible fit adjustments;
  • convenient and flexible adjustment to the user's weight.

Cons:

  • there are no significant downsides.

Slider can be conditionally added to the mechanisms in design of the chairs - it is not responsible for swinging, but regulates seating depth. Sitting in chairs with slider can be moved back and forth and fixed in different positions, moving away or bringing back of the chair closer.

Office chairs with anyfix mechanism

Summing up, the simplest piastre swing mechanisms, permanent contact and freestyle are usually used on board inexpensive office chairs. Tilt and deep tilt are the «golden mean» with optimal set of adjustments for comfortable landing. Anyfix and multifix are almost the same, but with the option of fixing backrest in any intermediate tilt position. But the chic in terms of variety of adjustments, durability and reliability - these are the swing mechanisms multiblok and their varieties.

Finally, it is important to note that swinging mechanism is by no means the only criterion when choosing computer chair. “How to choose computer chair” in general - read in our separate material.