Hydraulic Control System
Except for the low pressure pneumatic controllers, compressed air is rarely used to control the movement continuity tools that have mass. Comparison between pneumatic systems and hydraulics systems. The fluid that is commonly found in the pneumatic system is air. In the hydraulics system, the fluid is oh or lubricating oil. Differences in the properties of the fluid mainly be significant differences in the characteristics under external load Kingdom.
For such cases, the controller hydraulics generally preferred. The use of which extends from the circuit hydraulics in application aids machine, the control system of the aircraft, and the operation is similar to that occurred because of factors such as its positive, accuracy, flexibility, ratio of horsepower-to-weight, start fast, stop and backward smoothly and precision, and simplicity of operation.
Operating pressure in the hydraulics system of about 145 and 5000 lb / in2 (between 1 and 35 MPa). In some special applications, tekananoperasi perhaps up to 10,000 lbf / in2 (70 MPa). For the same power requirements, weight and size of the hydraulics unit can be made smaller by increasing the supply pressure. In the high-pressure hydraulics system, a very large force can be obtained. Action fast, precise positioning of laying a heavy burden made possible with the hydraulics system.
A combination of electronics and hydraulics systems are used widely, because he kelebihankelebihan either of the control electronics and power hydraulics. There are certain advantages and disadvantages dal compared to other systems. Some strengths are:
1. The hydraulic fluid acts as a lubricant, in addition to carrying away the heat generated in the system to a good heat exchange (heat exchanger convenient).
2. Actuators hirdolika the comparatively small size can develop a large force and torque.
3. The hydraulic actuators have a higher response rate to start, stop, and reverse a rapid pace.
4. The hydraulic actuator can be operated under a state of continuous, terputusputus (intermittent), inverse, and slowed down without damage.
5. Availability of linear and rotary actuators behind providing flexibility in design.
6. Due to the low leakage in the hydraulic actuator, the speed will fall when the applied load is small.
On the other hand, some shortcomings tend to restrict its use:
1. Power hydraulics are not readily available as compared to electric power.
2. The cost of the hydraulics system may be higher than comparable electric system and the functions that are similar.
3. The danger of fire and explosion exist, kecuall if using fire-resistant fluid.
4. Because it was difficult to take care of hydraulics system that is free of leaks, such systems tend to be dirty.
5. The contaminated oil may cause failure of the hydraulics system to function properly.
6. As a result of the non-linear characteristics and other complex characteristics, the design of sophisticated hydraulics system is in need of substantial time and effort.
7. The circuit hydraulics generally have a poor damping characteristics. If the hydraulics circuit is not designed properly, then some unstable phenomena may occur or disappear, depending on the state of operation.
