Features of the design and device of an office chair

An armchair is one of the key pieces of furniture in a modern office, which provides a comfortable work for employees. There are many models, and when choosing, it is worth considering their main design features.

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The device and design features of office chairs
Varieties of mechanisms and their principle of action
What is a multiblock in an office chair
Computer chair gas lift device
The most common office chair breakdowns
Video: what is a pneumatic cartridge and why is it in a chair

The device and design features of office chairs

All existing office chairs can be divided into the following groups.

For leaders. They are distinguished by their large dimensions and solid appearance, most often upholstered with natural or artificial leather. They have the greatest number of functional capabilities, for example, a synchromechanism that provides repetition of the movements of a seated person with a back and a seat, mechanisms that regulate the depth of the seat, back resistance, negative tilt, and so on.
Chairs for the manager differ in comfort and size.
For staff. They must be comfortable and reliable, therefore, when choosing them, the main focus is on the shape of the seat and backrest and the gas lift mechanism, and not on appearance. They are lightweight, which allows for a high level of mobility, and modest functionality, which includes mechanisms that adjust the height of the armrests and seat, as well as the angle of the backrest. This group includes computer chairs and operator structures with armrests.

Note! Such chairs most often have fabric upholstery, which can be made in different colors.
For visitors. Such chairs should be, first of all, comfortable, beautiful and stable, and therefore they are devoid of any functionality whatsoever. They often have four stationary legs, without a spider on wheels and a rotation mechanism.
A modern armchair is a functional and comfortable piece of furniture.

Almost all models are equipped with armrests. Cheap designs are almost entirely made of plastic, while the more expensive ones are made of stainless or anodized steel.

Despite the existing differences, all chairs are composed of the following basic elements:

a five-beam cross, which is the base of the entire structure and is made of plastic or metal;
rollers, plastic or metal, with an internal hinge and metal fasteners;
pneumatic cartridge, or gas lift, which is the leg of the chair and provides elasticity;
swing mechanism, which helps to fix the chair in one position and deflection;
piastre, which looks like a metal platform equipped with a lever and is necessary to adjust the height of the seat;
permanent contact that connects the seat and backrest and is responsible for changing the position of the latter.

Multifunctionality is the main criterion when choosing a chair.

Note! Expensive models of chairs are equipped with a mechanism with an offset axis, which ensures the most smooth rocking process.

Office chairs have the following features aimed at the convenience of working at the table:

height adjustment, allowing you to choose the optimal seat height for each person;
a change in the inclination of the back, ensuring constant contact with the back, even when the position of the seated person changes;
pivotal rotation and mobility created by rollers.

Varieties of mechanisms and their principle of action

There are many mechanisms for office chairs, but the most common are the following:

Piastra. This spring-screw mechanism only allows the seat height to be adjusted. It is a block with a gas lift control lever, which provides a change in height.
Permanent contact. The most common mechanism that provides fixation of the back and its deflection at an angle of up to 128 °, which allows you to relax your back. Also responsible for adjusting seat hardness and depth.
Swing mechanism. It makes it possible to use the structure according to the principle of a rocking chair, while the deflection range of the seat and backrest is from 95 ° to 135 °. The pivot axis can be centrally located or biased forward.
Piastra is a lever block that controls the position of the gas lift.
Note! Rocking chairs are not recommended for people weighing more than 100 kg, as the used welded sleeve can break under high loads.
Anti-shock effect. This mechanism allows you to smoothly return the chair to the working position after swinging. To do this, the rocking mode is first blocked, and then the backrest is pressed.
Synchromechanism. It allows the seated position to change freely, initiates the swing mechanism, supports the back and prevents overturning. This is achieved by changing the seat tilt angle at the same time as the backrest tilt.
Note! The most comfortable ratio of changes is 1 to 3, that is, the seat deflects one degree when the backrest is deflected three degrees.

If the chair does not hold the "horizon", then the problem is most likely in the destruction of the swing mechanism.
Asynchronous mechanism. Allows you to change the angle of the backrest without reference to the position of the seat.
Slider. Allows you to adjust the depth of the seat, which slides forward with the ability to lock in various positions.

Asynchronous mechanism — An asynchronous mechanism, in contrast to a synchronous one, makes it possible to change the inclination of the backrest without affecting the position of the seat.

What is a multiblock in an office chair

The multiblock is a multifunctional mechanism for premium seats. It allows you to customize the design pointwise, according to your parameters and preferences. Withstands loads up to 120 kg.

assemble office chair — You can assemble the office chair yourself.

Has the following features:

seat height adjustment;
fixing the angle of inclination in the range from 0o to 135o;
activation and blocking of rocking;
stiffness adjustment;
Anti-shock effect that smoothly returns the chair to the working position.

If you are buying an office product, then the kit should include fasteners and keys for assembly.

The operation of the multiblock is controlled by a system of handles located under the seat.

Computer chair gas lift device

The gas lift is a body with a cylinder, in which a piston rod is located, with a free stroke. The cylinder is made up of a pair of tanks separated by an opening valve. When the chair is in the lower position, the piston is located in the upper segment of the cylinder.

When you press the lever to raise the chair, you press the button that opens the valve, which leads to the flow of gas from the first reservoir into the second. This gas exerts pressure on the piston, causing it to descend smoothly, which causes the chair to rise.

When the pressure on the lever is released, the valve closes and the position of the piston is locked. When the lever is pressed and a person is in the chair, the valve opens and the weight is applied to the cylinder, which goes down. At the same time, the piston pushes the gas, rising upward, which leads to a lowering of the chair.

The most common office chair breakdowns

Damage to the crosspiece

The main damage to this element is a breakdown at the junction of the beams. It is important to consider the material of its manufacture. The base is a hollow structure, inside which you can place a polypropylene pipe, suitable in cross-section and dimensions. The tube is rigidly attached to the damaged beam and base.

Note! Do not splice plastic elements with a soldering iron or glue due to the high load on the legs.

The best option is to replace the plastic structure with a base made of glass-filled polyamide.

Disassemble the office chair — Disassembling an office chair is not difficult.

Dismantling the crosspiece is carried out as follows:

Removing clips. They are usually not rigidly fixed.
Dismantling the piastre. The seat is mounted on a cone. It is necessary to disconnect the piastre from the pneumatic cartridge by tapping on the attachment point.
Removing the retaining clip. It is located in the recess of the upper segment of the gas lift.
Knocking out the gas lift. If the damage is serious enough, then this will not work. In this case, the slave cylinder is removed along with the bearing and seal.

office furniture settings — The efficiency of the work of those who use this furniture directly depends on the convenience and simplicity of setting up office furniture.

Destruction of the swing mechanism

In the event of a breakdown, the chair ceases to hold the "horizon". Dismantling this element is quite simple:

Unscrew the four fixing screws.
Knock the pneumatic chuck out of the mount.

chair movement — During movement, proportional unloading of the entire spine along its length occurs.

Complete replacement of the part is the preferred solution. You can use a welding machine to repair an old machine.

Note! Russian and Chinese standard movements differ in size.

Breakdown of the gas lift

If the integrity of the elements of the pneumatic chuck is violated, the rod does not extend when pressed. In this case, a complete replacement of the entire mechanism is required. It cannot be disassembled due to the gas pressure.

Also, quite often, the cause of breakdown is the bending of the adjustment lever, which is enough to bend, returning it to its original state.

Gas lift breakdowns occur for several reasons.

The design of a computer chair is quite complex, and at the same time extremely thoughtful. This ensures maximum comfort during use and allows for prolonged work in a sitting position.