When choosing a work chair for your home or office, it’s a good idea to figure out what the chair is made of and what details you should pay special attention to. Modern office chairs are developed by constructors and designers, increasingly also with the participation of doctors, with the expectation of a maximum number of users and in accordance with ergonomic standards.
A familiar and at first glance simple office chair is a kind of construction set consisting of a number of parts. The complex structure of an office chair is dictated by a large number of requirements and tasks that are placed on it. Next, we will try to answer the question of what a chair or office chair is made of. Let's look at each component in detail in turn.
Structure and design features of office chairs
All existing office chairs can be divided into the following groups.
- For managers. They are distinguished by their large dimensions and solid appearance, most often upholstered in natural or artificial leather. They have the greatest number of functional capabilities, for example, a synchronizing mechanism that ensures repetition of the movements of the seated back and seat, mechanisms that regulate the depth of the seat, back resistance, negative tilt, etc.
Executive chairs are comfortable and sized.
For the staff. They must be comfortable and reliable, so when choosing them, the main attention is paid to the shape of the seat and backrest and the gas lift mechanism, and not to appearance. They are lightweight, which allows for a high level of mobility, and have modest functionality, which includes mechanisms that regulate 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.
A modern chair is a functional and comfortable piece of furniture.
Almost all models are equipped with armrests. Cheap designs are made almost entirely of plastic, while more expensive ones are made of stainless or anodized steel.
Despite the existing differences, all chairs consist of the following basic elements:
- a five-beam cross, which is the basis of the entire structure and is made of plastic or metal;
- rollers, plastic or metal, having an internal hinge and metal fastening;
- pneumatic cartridge, or gas lift, which is the leg of the chair and provides elasticity;
- a swing mechanism that helps fix the chair in one position and tilt;
- piastra, which looks like a metal platform equipped with a lever, and is necessary for adjusting the height of the seat;
- permanent contact connecting the seat and backrest and responsible for changes in the position of the latter.
Multifunctionality is the main criterion when choosing a chair.
Note! Expensive chair models are equipped with a mechanism with an offset axis, which ensures the smoothest swinging process.
Office chairs have the following features designed to make working at your desk more comfortable:
- height adjustment, allowing you to choose the optimal seat height for each person;
- changing the tilt of the backrest, ensuring constant contact of the back with it, even when the sitting position changes;
- rotation around an axis and mobility created by rollers.
An office chair is a rather complex device and any of its structural elements can fail.
Cross
The base of the chair in the form of a four- or five-beam cross provides a stable position, but only if it has a sufficiently large diameter. Crosspieces come in plastic and metal. High-quality plastic provides lightness and good reliability, a variety of colors, but is still inferior to metal in terms of strength.
Metal crosspieces are durable, but also add several kilograms to the product. These crosspieces differ in design: shiny chrome or matte finish, plastic or wooden linings.
Types of mechanisms and their operating principles
There are quite a lot of mechanisms for office chairs, but the most common are the following:
- Piastra. This spring-screw mechanism allows you to adjust only the height of the chair. It is a block with a gas lift control lever, which provides height changes.
- Permanent contact. The most common mechanism that ensures the backrest is fixed and tilted at an angle of up to 128°, which allows you to relax your back. Also responsible for adjusting the rigidity and depth of the seat.
- Rocking mechanism. Makes it possible to use a design similar to a rocking chair, with the range of seat and backrest deflection ranging from 95° to 135°. The swing axis can be located in the central part or be shifted forward.
A piastra is a block with a lever that controls the position of the gas lift.
Note! Chairs with a rocking mechanism are not recommended for people whose weight exceeds 100 kg, as the welded bushing used may break under high loads.
Note! The most comfortable proportion of changes is 1 to 3, that is, the seat deviates by one degree when the backrest deviates by 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 extends forward with the ability to be fixed in various positions.
An asynchronous mechanism, unlike a synchronous one, makes it possible to change the tilt of the backrest without affecting the position of the seat.
Classification of computer chairs
Let's look at the main types of computer chairs:
- Operator's rooms. In most cases, these are the most budget options with few features. You don’t need to expect a high level of comfort from such a chair. However, they still have fairly large odds. In any case, they are better than ordinary chairs;
- "Director's" They are distinguished by their representative appearance, high back and complex adjustment mechanisms. The most comfortable chairs, but still you won’t forget that you’re at work. They often limit the range of backrest deflection. Such chairs cost very well;
- Gaming ones. The most convenient and expensive. They are equipped with very expensive swing mechanisms with a large number of adjustments. Often even the armrests can change in all respects. The backrest must be high and can recline to a horizontal position. From the outside it resembles an oak leaf. This is caused by the presence of lateral support components. Similar ones can be on both sides of the seat. These chairs are very often equipped with additional “features” in the form of mug holders, stands for a tablet computer, removable pads and the like;
- Orthopedic. They stand out for their very high rigidity. The backrest on the side resembles the letter Z. In the area of the lumbar region there is a significant inward deflection, which plays the role of a support roller. The backrest is medium (up to the shoulder blades) or high (with support for the head). Very often they are covered with acrylic mesh;
- Children's. The main thing to understand here is that the chair should “grow” along with your baby. You will never be able to choose a multi-functional model for all times. It would be nice to have no armrests. In children, this habit provokes spinal curvature. Because very often they rely on only one of which. The child's feet must reach the floor so that the foot stands straight. In this case, worry about a cross with thrust bearings or the presence of a specialized footrest. Children rarely sit upright. Better models with a headrest and lumbar bolster. You should not choose rotating models. This way you will save your own mischief maker from the risk of serious injury.
What is a multiblock in an office chair?
The multiblock is a multifunctional mechanism installed on premium chairs. It allows you to customize the design point-by-point, according to your parameters and preferences. Withstands loads up to 120 kg.
You can assemble your own office chair.
Has the following functions:
If you buy an office product, the package should include fasteners and keys for assembly.
The operation of the multiblock is controlled through a system of handles located under the seat.
Computer chair gas lift device
A gas lift is a housing with a cylinder in which a rod and piston are located that have free movement. The cylinder is made up of a pair of reservoirs separated by an opening valve. When the chair is in the lower position, the piston is located in the upper segment of the cylinder.
In case of critical damage or destruction, it is impossible to knock the gas elevator out of the base.
When you press the lever to raise the chair, you press on a button that opens the valve, which causes gas to flow from the first reservoir to the second. This gas puts pressure on the piston, causing it to lower smoothly, causing the chair to rise.
A gas lift for an office chair is a type of spring in which gas acts as an elastic element.
When the pressure on the lever stops, the valve closes and the position of the piston is fixed. When the lever is pressed and a person is in the chair, the valve opens and the weight acts on the cylinder, which moves down. At the same time, the piston pushes out the gas, rising upward, which leads to the lowering of the chair.
The most common breakdowns of office chairs
Damage to the cross
The main damage to this element is a breakdown at the junction of the beams. It is important to consider the material it is made of. The base is a hollow structure, inside of which you can place a polypropylene pipe of suitable cross-section and dimensions. The pipe is rigidly fixed to the damaged beam and base.
Note! You cannot splice plastic elements using a soldering iron or glue due to the high load on the paws.
The best option is to replace the plastic structure with a base made of glass-filled polyamide.
Disassembling an office chair is not difficult.
Dismantling the cross is carried out as follows:
- Removing rollers. Usually they are not rigidly secured.
- Dismantling the piastres. The fastening to the seat is carried out “on a cone”. It is necessary to disconnect the piastrum from the pneumatic cartridge by tapping at 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, this will not work. In this case, the working cylinder is removed along with the bearing and seal.
The convenience and ease of setting up office furniture directly affects the work efficiency of those who use this furniture.
Destruction of the swing mechanism
If it breaks, the chair stops holding the “horizon”. Dismantling this element is quite simple:
- Unscrew the four mounting screws.
- Knock the air cartridge out of the mount.
During movement, a proportional unloading of the entire spine occurs along its length.
The preferred solution to the problem is to completely replace the part. You can use a welding machine to repair an old mechanism.
Note! Russian and Chinese standard mechanisms differ in size.
Gas lift failure
If the integrity of the pneumatic cartridge elements is damaged, the rod does not extend when pressed. In this case, a complete replacement of the entire mechanism is necessary. It cannot be disassembled due to gas pressure.
Also, quite often the cause of breakdown is the bending of the adjustment lever, which just needs to be bent and returned 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 you to work for a long time in a sitting position.
What is
The gas lift used in office chairs is a device that is similar to the lifting mechanism of a dump truck, but smaller. Its other name is gas spring. Externally, it is a metal pipe with two parts of different sizes. The gas lift mechanism is fixed in the upper part to the base of the seat, in the lower part it is attached to the cross. The lifting height depends on the size of the pneumatic cartridge, the length of which varies from 13 to 16 cm. Gas lift functions:
- Seat position adjustment. When you press the lever, the structure rises if you stand up a little to reduce resistance, or lowers under your body weight.
- Reducing sudden load on the spine area. When lowered into the chair, the mechanism works as a shock-absorbing device. The seat is springy, significantly reducing the load on the spine.
- Possibility of rotation 360 degrees. Due to the features of the system, you can easily reach objects that are at arm's length, located on both sides.
The hydraulic cylinder is configured for actions that are necessary when working simply at a desk or at a computer.
Rollers
The mobility of the chair is provided by rollers - small wheels that are attached to each of the beams of the cross. The materials used are various types of plastic. A chair on hard plastic wheels is chosen for soft flooring. Whereas soft rollers made of polyurethane or with a special rubber coating will work better on hard and smooth floors.
Construction device
The design of a gas lift for a computer or office chair includes the following elements:
- Button. The part is located under the seat and serves to open and close the valve.
- Gas valve. Opens when it is necessary to change the height of the seat, fixes the structure.
- Bushings and seals. They serve to tightly connect parts and also provide sealing of containers.
- External and internal cavities. Designed for gas passage.
- Passageway. Needed for height adjustment.
- Lifting rod. When the height of the chair increases or decreases, it protrudes from the body or hides back.
- Support bearing. A simple device thanks to which the chair can rotate in the desired direction.
It is not recommended to disassemble gas lifts yourself; violating their integrity is dangerous for humans.
Principle of operation
The operating principle of a gas lift for office chairs is simple. A rod with a piston moves along a cylinder located in a body made of metal. There are two containers in the pipe, and between them there is a valve. It can be in a closed or open position, when gas moves from one cavity to another along the passage channel. When the seat is positioned at the bottom, the piston is located at the top. When the lever is pressed, gas moves from one container to another. In this case, the piston moves down and the structure rises.
To fix the seat at the required height, the lever is lowered, the valve closes, and the lifting of the chair stops. To lower, the lever is pressed, and the structure begins to lower under the weight of a person. The gas piston allows the chair to be adjusted in height and rotated around its own axis. A special spring significantly reduces the load on the spine during a sharp landing, thereby preventing many diseases.
Armrests
The main function of the armrests is to provide a comfortable position for your hands while working. Depending on the material used, armrests are made of plastic, metal and wood. In addition, many armrests “can” be adjusted in the vertical plane (that is, in height), in the longitudinal plane (forward-backward, left-right), as well as in the angle of inclination. It is customary to equip truly ergonomic chairs with adjustable armrests.
Varieties
The gas lift for the chair is produced in several modifications, therefore, in order to choose the right option, you need to know the types of mechanisms and their features. The products are made from high quality steel. When choosing, attention should be paid to classes that depend on the thickness of the material:
- Class 1. Steel thickness is 1.2 mm. Budget option.
- Class 2. Inexpensive device, the performance of which is slightly improved. Thickness – 1.5 mm.
- Class 3. Withstands loads up to 120 kg. Thickness – 2.0 mm.
- Class 4. Reinforced structure with 2.5 mm steel thickness, supporting a weight of 150 kg.
Another difference between gas lift models is the body diameter. Available in the following sizes:
- 50 mm is the most common option, used in 90 percent of chairs;
- 38 mm - used in rare cases, mainly for executive chairs, which have a high cross.
An equally important aspect is the length of the gas lift. The range of height settings depends on this parameter. Length options:
- 205-280 mm. This option is used on inexpensive office products that are designed for sitting at standard tables. This gas lift is short because it has a small range of adjustments.
- 245-310 mm. It is used in places where it is necessary to raise the structure higher. The length of the device is longer, but the range of lift settings is less than that of the previous model.
- 290-415 mm. The longest mechanism with great height adjustment capabilities, allowing for significant position changes.
These types of gas lifts are the main ones; other models are also produced, but they are used very rarely.
Specifics of computer chairs - benefits and necessity
Someone might think they are all built on the same principle. This is a very misleading impression, causing many to save on their purchase. In reality, each type of chair has different mechanisms, comfort and adjustment. Their main task is to help avoid significant stress placed on the legs and back during long hours of sitting. Due to this, a large number of significant disorders with joints and blood circulation develop.
It’s easy to figure out a computer chair, regardless of the large selection of models:
- Cross with rollers. At this time, this type of support has boldly replaced chairs with legs from work places of all categories. This can be explained by saving time when moving. You won't have to get up again;
- Ability to adjust the height, tilt angle and placement of all chair components. An ordinary chair cannot boast of this;
- Availability of gas lift. This mechanism makes it possible to change the height of the entire structure along with you according to several indicators;
- All models are something between an armchair and a chair, retaining the characteristics of both types of furniture.
Is it possible to do without gas lift?
Some users, when purchasing an office chair, prefer models without gas lift, considering the device useless. But no seating furniture without such a system will be comfortable and convenient. This is especially true in workplaces where people are present for long hours. In addition, chairs are often used by several employees who have different heights and weights. The 360-degree rotation function of the structure greatly facilitates the work process - if you need to grab something from the side or behind, you don’t have to stand up, just turn around.
But functional chairs are popular not only in offices; at home, several family members can also be at the computer, using one seating area. For this reason, the adjustment function is necessary everywhere to create comfort, convenience, and reduce stress on the back. A gas lift is especially needed for chairs used by children, since their posture is just developing.
Tips for choosing
Gas lifts for office chairs, like all devices, can fail over time, but you can repair them yourself. Breakdowns are usually caused by:
- Manufacturing defects. The phenomenon is rare, but sometimes occurs, especially in budget products. If the warranty period has expired, the repairs are carried out independently.
- Gas lift overload. There are situations when a structure designed for one weight is used by a heavier person or two people sit on it. Then the parts of the mechanism wear out much faster and more severely.
- Incorrect operation. Damage occurs if you sit down suddenly or take a running start. The device is overloaded, which can lead to the valve being squeezed out.
The documents included in the package contain information about the maximum permissible user weight. Basically, this is 100 kg, but more expensive and reliable devices are produced, which are designed for 120 and 150 kg.
If the gas lift for an office chair breaks down, it is not enough to repair it; it is important to choose the right new design. The correct choice is very important, since discrepancies in parameters will again lead to rapid wear. The following points should be taken into account:
- Product dimensions. The structures are manufactured with different dimensions, so the gas lift is selected in accordance with them.
- Cup holder diameter. It comes in two types, so choosing the right option is easy.
- Gas lift height. It is necessary to measure the length of the product, taking into account the fact that part of it is located inside the cross.
- Maximum load. The product class should be selected depending on the weight expected during operation. Moreover, the fact that other people can use the chair is also taken into account. If a piece of furniture is at home, then most likely all family members will sit on it.
Gas lift plays a very important role in office and computer furniture. The chair is designed in such a way that the spine does not get tired when sitting for a long time. The mechanism makes it easier to work in the office and makes staying at your home computer more comfortable.
Back
Bearing a significant load (about 25 percent of the user's weight), the backrest is made from the same reliable materials as the seat. The back of the chair must have an anatomically correct shape that matches the curves of the spine. Ergonomic backrests are equipped with adjustable lumbar support or a removable lumbar bolster.
