Basically, shock absorbers are designed to dampen the vertical vibrations. But do not forget about the impact of shocks on acceleration, braking and handling dynamics . When overclocked car crouches back, loading and unloading the rear -wheel drive , reducing their grip. When braking - on the contrary, when maneuvering load shifted to the sides of the car. In all cases, the ideal would be a state in which the vehicle is maintained to a horizontal position. Problem absorbers - hold the wheel in constant contact with the road, that is, the wheel must be as gently as possible and clearly go around the obstacle and just as clearly and quickly back on the road, providing the necessary grip . Spring or springs support the weight of the car, the rest take the shock.
When working damper is necessary to provide a variety of options and features for its functioning . Real way is more complex coating than in theory, the car does not always travels in a straight line . For example, several successive bumps forced to work intermittently shock : not having to straighten it again should work in compression. Required to ensure a comfortable obrabatyvanie fine irregularities on large bumps avoid full compression damper. Need a compromise between comfort and handling. Next problem - heat buildup. The higher viscosity than the liquid or the bypass hole of the piston, the greater the rigidity of the shock absorber and the temperature is more released during its operation . Heat dissipation - an important task. But subzero temperature gives a lot of problems. With a large red oil contained inside the shock absorber, thickens, making shock stiffer . Everything is decided by proper selection of oil. Next question - aeration. Modern dampers along with oil and gas are present, they may be mixed during operation, while the oil is whipped to a froth. Foam, unlike oil, compressed, which drastically reduces the damping efficiency. Another important question - the location of shock absorbers. The most favorable, from the standpoint of work place - as close as possible to the wheel, perpendicular to the plane of the suspension. Installing the damper angle reduces its damping efficiency. As in any other area, there are various design solutions. By construction, the shock can be divided into several basic types. The architecture they are divided into one-and two-pipe. Filling: liquid (hydraulic) and gas (with a hydraulic gas overpressure). There are pure gas shock absorbers, which uses very high gas pressure (60 atm), but they are rare.
Hydraulic twin tube shock absorbers - the most common and cheapest type . They are simple in design and undemanding to manufacturing quality. Shock consists of two tubes of: operating the flask where the piston and the outer housing, for storing the excess oil. The piston moves in the inner flask oil flowing through the channels and squeezing out some of the oil through the valve located below the bulb. This compression valve, he is responsible for the flow of oil in a given cycle. This portion of liquid seeping into the space between the bulb and the outer casing, wherein compresses the air contained under atmospheric pressure in the upper portion of the shock absorber. When reversing valve of the piston are utilized by adjusting the force on the rebound. For a long time such a structure dominated by the market shock absorbers. But years of operation revealed a number of its shortcomings. The main disadvantage - aeration, especially with heavy use. Replacing air with nitrogen improved the situation, but did not solve the problem completely . Moreover, such shocks, with a double hull, worse cooled, which negatively affects their work. On the other hand, if making them larger diameter, damping characteristics can be improved by reducing the operating pressure and, as a consequence, the temperature.
Hydropneumatic ( gas- oil or "gas" as they are commonly called, although it is not quite so ) dampers are similar in design and function to the conventional hydraulic twin-tube racks. The main difference is that instead of air at atmospheric pressure is under a nitrogen pressure of 4 to 20 atm . This so-called gas backwater . Gas pressure can be different for different vehicle operating conditions . The larger diameter , the smaller the necessary pressure gas inlet pressure . It may be different for the front and rear shock absorbers. Why the need for gas backwater ? Firstly , to deal with aeration . Pressurized gas is not mixed with oil too active , that improves the performance of the shock absorber. In addition to reducing oil aeration gas back pressure helps to maintain the car , as an additional damper . That is, even if the springs would have shrunk , the gas charge in the damper keeps the car , which has a positive effect on handling.
Monotube dampers consist of a single bulb, which is the working cylinder and the housing simultaneously. They work in the same way as two-pipe , but the gas is in the same cylinder and is separated from the oil by a floating piston (so-called circuit De Carbon). Gas (nitrogen ) is located in its chamber separated from the oil , under high pressure ( 20-30 bar) . Monotube shocks have lower compression valve as two-pipe . The entire job of controlling the resistance under compression and rebound when the piston takes . These dampers are high performance. In addition, they effectively cooled as air is blown directly to the slave cylinder . Plus, with the same dimensions as the twin-tube shock absorbers, an inside diameter of the flask and the piston diameter will be larger. This means a greater amount of oil , the more stable and better heat transfer characteristics . There are also disadvantages . Unlike the twin-tube , monotube shocks are more sensitive to external influences. Jammed leads to replacement of the bulb bar, whereas the double-tube outer cylinder reserved . Furthermore, the high sensitivity to temperature. The higher it is , the higher the pressure of the gas inlet pressure and shock absorber works harder. On the other hand , single-tube rack can be installed anywhere as tight gas separated from the oil by a floating piston . When installing this damper rod down reduced unsprung masses .
Dampers can be found wearing the spring. This embodiment is not only applies to the single-pipe racks . This adds an additional elastic element , sometimes it replaces the main spring . Such constructions often have the ability to adjust the clearance of the vehicle. Twisting special screw nut on the shock body , supported by a spring bottom , you can raise or lower the car. Evolution models are monotube shocks with external compensation chamber . Chamber with a gas inlet pressure has been taken outside of the shock absorber in a separate container . This design allows without increasing the size of the shock absorber to increase gas and oil , which is very positive effect on the thermal balance and stability characteristics. These shock absorbers have a larger stroke . However, an even greater effect on the remote camera is that the path of oil flow from the primary operating cylinder in the additional chamber , the valve system can be set , which will play the role of compression valve , in the double pipe structure . Separated by a valve working on the compression and rebound , you can lay a lot of the adjustment ranges . You can change the stiffness of the shock absorber for different speeds of movement of the piston . Sometimes you can find a set of system and overflow valves . Besides a large external tank , shock absorber is equipped with several tubes , which are located at the ends of the adjusting head . On these tubes of oil bypassed over subpiston cameras and each other. By adjusting these passageways , you can get the desired characteristics of the shock absorber at certain positions of the piston ( modes) . Such dampers are sensitive..