This device in the general sense is a volumetric engine with reciprocating or reciprocating movements. The operating principles of the hydraulic cylinder are widely used in aerospace, aviation, road construction, as well as in hoisting and transport machines and in the earthmoving industry. The mechanism has found application in a variety of equipment, including press-forging machines and metal-cutting machines.
Device Description
If we consider the simplest case, then we can say that a hydraulic cylinder is a sleeve in the form of a cylindrical tube with an inner surface that has undergone careful processing. Inside the device there is a special piston with cuffs in the form of rubber seals. The latter serve to ensure that the working fluid does not flow through the divided cavities of the cylinder. In operation, special mineral oils are used. The device and principle of operation of the hydraulic cylinder imply the supply of fluid into the cavity. The piston receives a certain pressure and starts to move.
Proper selection of a device requires knowledge of someimportant characteristics. First you need to select the appropriate piston diameter, that is, the value of the pushing or pulling force of the hydraulic cylinder. A significant role is also played by the value of the diameter of the rod. This parameter is selected depending on the required load capacity and dynamic load level. If the value is incorrectly selected, the rod may bend during operation. The stroke of the piston, in turn, affects the direction of movement of the working body and the overall dimensions of the device in the unfolded state. When assembled, the dimensions are determined by the distances along the centers. The mounting method of the hydraulic cylinder depends on its design.
General principle of operation
The force from the piston through the rod is transmitted to the polished surface of the rod. The correct direction is determined using the grundbuksa. The processes of supply and discharge of the working fluid in the cylinder occur through two covers fixed in the sleeve. Also, the stem has a seal of several cuffs. The first of them serves to prevent leakage of the working fluid from the hydraulic cylinder, and the second collects dirt that gets inside. The movable mechanism and the threaded rod are connected by a special part or eyelet, which provides movable fastening of the unit body.
There are two main principles of operation of the hydraulic cylinder - controlled by a hydraulic valve or due to certain means for adjusting the hydraulic drive. At the same time, all operating mechanisms are manufactured with increased strength andreliability. Structural elements such as a cylinder and a control unit operate at high pressures up to 32 MPa. In order to better understand the mechanisms of action of such aggregates, one should consider their main current varieties.
Single acting hydraulic cylinders
In such devices, the stem is extended by the pressure of the working fluid in the piston cavity. Return to the starting position is carried out by spring force. When compared with the principle of operation of a double-sided hydraulic cylinder, one important nuance can be noted. Other things being equal, the force in a one-sided unit is less. This is due to the fact that the direct stroke of the stem implies the need to overcome the elastic force of the spring in the mechanism in question.
An ordinary jack can serve as a striking example of a single-acting hydraulic cylinder. In this case, the spring is used as the main return element. However, in some cases there is no need to use this part at all. For example, the return can occur due to the gravity of the lifted load, another unit, or by means of a drive mechanism.
Double acting hydraulic cylinders
Here, the working fluid also creates pressure on the rod. As the cavity of the hydraulic cylinder is selected, respectively, piston or rod. The forward stroke is capable of creating more force, but the speed of movement of the working fluid is less. Atreverse movement, the picture is exactly the opposite.
This principle of operation of a double-acting hydraulic cylinder is based on the difference in areas to which the pressure force of the working fluid is directly applied. Such devices are ubiquitous, for example, when lifting and lowering blades on most bulldozers. The main role is played by the effective cross-sectional area.
Operation of hydraulic locks
The design of this element is based on the type of hydraulic cylinder. A one-way device is characterized by the presence of a seat, a shut-off and control element in the form of a ball, a piston with a pusher, and a spring. The principle of operation of the hydraulic cylinder and its lock is that in the absence of pressure in the control line, the working fluid flows from one channel to another, thereby shifting the ball. However, the reverse motion does not occur, because under the action of the flow, the shut-off and control element is firmly pressed against the seat. If there is pressure in the control line, then the working fluid moves freely between the two channels.
In a double hydraulic lock, two check valves are combined at once. They are located in the same housing so that the control line of each of them is connected to the input of the other. The principle of operation of the hydraulic lock of the hydraulic cylinder in this case is based on the fact that the working fluid moves in the opposite direction only if there is pressure in the compartment. At the same time, each oftwo sides of the mechanism works independently.
Design options
Among the main types are plunger, piston and telescopic devices. The principle of operation of a plunger hydraulic cylinder involves the supply of a working fluid into the cavity, where the plunger begins its displacement due to the action of increased pressure. The unit is able to return to its original state due to the effect of external force on the end of the rod.
Piston hydraulic cylinders are the most common. The main difference between such devices and plunger ones is the ability to create a pushing or pulling force. The rod cavity communicates with the atmosphere through the breather, however, dust and dirt particles do not enter the working surface.
Telescopic hydraulic cylinders
These devices got their name due to their resemblance to telescopes or spyglasses. The versatility of these hydraulic cylinders allows the use of both one-sided and two-sided mechanisms in their basis. Most commonly used for lifting and lowering dump truck bodies. The principles of operation of a telescopic hydraulic cylinder require a large piston stroke with relatively compact overall dimensions of the device itself.
