Hydraulic System

I. BASIC PRINCIPLES OF HYDRAULIC SYSTEM.

In a hydraulic system fluid flow serves as a successor force. Mineral oil is a common type of fluid used.
The nature of the liquid:- Does not have a fixed shape, always adjust the shape they occupy.- Liquids can not be compressed.- Continuing pressure in all directions.

Hydraulics can be expressed as a means of transferring power by pushing a number of specific liquids. Component called a pressurized fluid flow generator pumps, and hydraulic pressure converter components into mechanical motion (straight / rotation) are called the working elements (cylinders / motors hidroulik).
The advantages of hydraulic systems:
- Flexibility in the placement of power transmission components.- Style is very small can be used to transport a large force.- Successor style (oil) also serves as a lubricant.- Expenses can be easily controlled using the pressure regulator valve (relief valve).- Can be operated at varying speeds.- Direction of operation can be reversed immediately.- It's safer if operating at overload.- Power can be stored in the accumulator.
The weakness of the hydraulic system:
Hydraulic systems require an environment that really clean. Its components are very sensitive to the damage caused by dust, corrosion and other impurities, and the heat affects the properties of hydraulic oils.


II. EQUATION / FORMULA BASIC.

Pressure is the force per unit cross-sectional area.In the equation expressed as:

P =, where P = Pressure / Pressure (Pascal).F = Force / force (Newton).A = Area / area (meter 2)
Capacity is the amount of flow per unit time.In the equation expressed as:

Q =, where Q = Capacity / Debit (m3/sec).V = Volume of Fluid (M3).t = Time (sec).
Or, Q = A x V, where A = Area (Meter 2).V = Fluid velocity (M / dt).
Boyle equation:
P1 x V1 = P2 x V2, where P = PressureV = Volume
Continuity equation:
Q1 = Q2 A1 x V1 = A2 x V2

Conversion unit:
- 1 Pascal = 1 Newton / meter2 (Pa = N/m2)- 1 bar = 105 Pa = 100 kPa= 14.7 psi (lbf / in2)= 1 Kgf / cm2- 1 m3/sec = 60 M3/menit- 1 M3/menit = 1000 LPM (liters / min).


Example:

Two related vessel, Style in vessel 1 (F1) = 1000 N.The diameter of the vessel 1 (d1) = 10 cm2Diameter of vessel 2 (d2) = 40 cm2Style on vessel 2 (F2) = ... ... ... ... .. ?


Completion:
- On Vessel 1:
Pressure 1 (P1) =

F1 = 200 N
A1 =; d1 = 10 cm 2 = 10 x 10-2 m2= 0.1 m
A1 = = 7.85 x 10-3 m2

P1 = = = 127.388 x 103 N/m2

= 1.27388 x 105 N/m2
= 1.27388 x 105 Pascal = 1.27388 Bar
- The vessel 2:
According to the law of Pascal 'Pressure in a closed vessel will be forwarded all directions with the same great'.- The pressure in vessel 1 (from calculation) = 1.27388 N/m2- In accordance with the laws of pascal the pressure on the vessel 2 will be equal to the pressure on the vessel 1.- Pressure in the vessel 2 (P2) = P1 = 1.27388 x 105 N/m2.
- Style on bejana2 (F2)
P2 =, then F2 = P2 x A2

P2 = 1.27388 x 105 N/m2
A2 = d2 = 40 cm = 40 x 10-2 m2= 0.4 m2
A2 = = 0.1256 m2

F2 = P2 x A2= 1.27388 x 105 N/m2 x 0.1256 m2= 16,000 N
So by using the principle of hydraulics can be concluded that with a small force F1 (1000N) to produce a much larger force F2 (16,000 N).


III. HYDRAULIC FLUID.

The function of the hydraulic fluid:
- As a mover / successor force.- Lubricating the parts that rub against each other.- Gap-filler (seal) the distance between the two areas that do friction.- As a cooling or heat sink caused by friction.
Terms of hydraulic fluid:
- Able to prevent corrosion or contamination.- Able to prevent the formation of sediment.- Not easy to form a froth-foam oil.- Stable & able to maintain the value of viscosity.- Can separate the water content.- In line or match the baffle / seal and gaskets used in the component.
The most important thing to consider in the selection of hydraulic fluid is the "viscosity", because the viscosity will affect the ability to flow and lubricate the parts that bergesakan. Hydraulic fluid viscosity expressed by Value viscosity.
In the selection of oil viscosity value should refer to the manufactur pump / hydraulic system for the system to work optimally.
Yag high viscosity oil to provide good filling of the gap (gap) of pumps, valves and hydraulic motors, but if the value is too high viscosity will result in:- Obstacles are large, causing friction seretnya activator element (actuator) and pump cavitation (air entry into the pump).- Use of force increases, due to friction losses.- Decrease stress increases through the channels and valves.
If the oil viscosity is too low, will result in:- Disadvantages of excessive leakage.- Aus excessive because of insufficient lubrication in pumps and motors.- Lowering the efficiency of motors and pumps.- Oil temperature rise or increase due to leakage losses inside.
Oil viscosity value is given by: absolute viscosity: poise or Centipoise (Cp). kinematic viscosity: Centistoke (CST). relative viscosity: SUS (Saybolt Universal Second). Figures coefficient Society of Automotive Engineers (SAE). Degrees Engler (OE)
In the Standard International (SI) values expressed by viscosity kinematic viscosity (cst).
Example: ISO VG 68 -  has a value of 68 cst viscosity at temperatures of 40oC.





IV. Pressure Regulating VALVE(TIMER VALVE PRESSURE)

Pressure regulating valve used to regulate the pressure system or subsystem of a hydraulic circuit. There are several types of valves for which the function of these valves in the circuit as a basis for penamaannya.
Some of the Valve which fall in rressure Pressure regulating valve is a relief valve (relief valve / safety pressure), Pressure reducing valve (pressure valve). Unloading valve, valve Offloanding, Counter balance valve and valve Sequence
a. Pressure Relief Valve
- Used to overcome the maximum pressure in the series or sub-system circuit, thus providing protection against overload.
- Symbols
NC valve

b. Pressure Reducing Valve
- Used to reduce or lower the limits of pressure from the main circuit into a lower pressure at a sub-circuit.
- Symbols


c. Unloading Valve
- Used to provide the direction of flow through the pump into the tank, while the system must be maintained (unloading system).Also called filler valve accumulator.
- Symbol.



d. Offloading Valve
- Used to provide the direction of flow through the pump into the tank while the system pressure is not maintained (off loading system).
- Symbols




e. Counter Balance Valve
- To provide the fluid flow resistance when the pressure limits which can be selected (style balancer).


- Symbols



f. Sequence Valve
- Used to create movement in a system in a sequence-specific sequences and to maintain a predetermined minimum pressure in the primary channel while the secondary operation is ongoing.
- Symbols



V. STEERING VALVE.(Directional VALVE)
Valve guides in particular as expressed in its name is set the direction of fluid flow. These valves are used in hydraulic circuits to provide control functions, such as: Set the direction of movement of the driving element. Selecting alternative control circuits. Perform control function logic.
Symbols used to represent the valves in the circuit diagram is determined only by the valve function, and not stated in the draft principles on the construction of the valve. The position of the valve displacement is represented or expressed by the square.
 The number of adjacent rectangles indicate the number of positions that belongs valve displacement, the side picture shows the two positions.
 The functions and working principles are described in the rectangular box. The line shows the path of fluid flow, and arrows indicate the direction than the flow. In the figure indicate the direction of flow increases.
 Position closes stated in a rectangular box by right-angled lines (symbol letters - T).
 Meeting hole flow expressed by a point.
 The holes channel (incoming and outgoing channels) indicated by the line depicted on the exterior of rectangular boxes, show the normal or initial position is also the number of hole lines, the picture shows the four channels.
 The position of the other obtained by sliding the rectangular box until flow hole (channel) met and in accordance with the connections.
 transfer valve with three positions, the middle position = neutral position, the position expressed by the letters a, b and 0.
 To ensure that the valve is properly installed, connections are stated with capital letters (roman).Working channel A, B, C ... ...The connection of P ... ... ... ... ...Disposal (the reservoir) T ... ... ... ... ...Control channels X, Y, Z ... ...

From the basics of reading symbols on the face of the valve guides could be developed into the types of valve guides that are widely used in the hydraulic circuit. And in the description or naming such valves 4/2-way valve just mentioned.
Example: Valve 4 / 3 - way, is a 4 channel connection, 3-position displacement (3 rectangle).
Valves 3 / 2 - way, is a 3-channel connection, the transfer of 2 positions (2 rectangles).

Rectangular boxes 1, 2, 3 indicate the position of displacement.- P, A, B, T indicates the channel.- X, Y is the channel guide (Hydraulic).


Closing Or Normal Valve Position Opening:
In a series of frequently used the term hydraulic valve normally open position (normaly Open / NO) or normally closed valve position (normaly Close / NC). The term - the term is often used in the valve with three-hole channel.


- Normal Position of Valve Closing (normaly Close / NC).
Valve shown in the following figure is the valve 2 position with 3 (three) holes channel



Valve shown in the picture are two position valves with a three-hole channel, whereas in the normal position (emphasis spring force) does not provide opportunities flow from hole to hole pressure P channels to the outside A.

- Valve Position Normal Opening (normaly Open / NO).
In this normal position the valve opening pressure lines like the following picture P are given the opportunity to flow into the hole to the outer channel A, while the valve is in its normal position.






Working Principle Steering Valve




In the normal position (neutral) all closed channels, while the handle is moved forward channel P connect with the channel A and channel B terhubug with T channels, whereas if the handle backward channel digerakkkan P connect with channel B and channel D connect channel T.

Valve Activator
The valve can be driven by five basic methods, ie by human power, mechanically, electrically, hydraulically, or by pnematik.
Applications in machine using some of the things set out in advance, or even by a combination of several drivers to obtain an optimum control system. Method of controlling human labor using hand or foot movement as the lever, press the button, knob and foot pedals.
Here are some symbol of the driving hydraulic valves, hydraulic symbol which can be found in appendix.


Pedal Lever Hydraulic Solenoid Springs Guide
VI. HYDRAULIC PUMP, ELEMENT DRIVER AND accumulator


HYDRAULIC PUMP
Function than the pump is to convert mechanical energy into hydraulic energy by pressing the hydraulic fluid into the system.In a hydraulic pump system is a tool to induce or evoke the flow of fluid (to remove some fluid volume) and to exert forces as needed
The pump is generating the flow rather than pressure.
Often considered that the pump is generating fluid pressure, but the true purpose of the use of hydraulic pump is to produce flow. Medium pressure is the force of unity posed by the existence of widespread and resistance to flow.
In terms of the resulting displacement volume, the hydraulic pump also can be divided into two parts, namely:
• Pump displacement fixed (fixed).• Pump displacement change - change (variable).
In the fixed displacement pump, the pump will move or remove an amount equal volume of oil in each round (cycle). This volume would only change when the pump rotational speed (rpm) is also changed.With fixed displacement pumps are usually found in lower pressure systems or as an auxiliary pump another in a higher pressure system. At the pump with a displacement not fixed (variable) can give the oil displacement volume varies in each round, even in the same rotation speed though.
Meanwhile, if viewed from the pump type hirdlolik can be divided into three namely gear, pump blades, and the pump piston.
Hydraulic Pump Symbols:













DRIVER ELEMENT

Hydraulic power converted into mechanical energy by using the driving element. Activator element that is used in hydraulic systems there are three kinds:
- Element activator linear (straight line) which is also called cylinder- Element drive rotary (spinning), which is also called the hydraulic motor- Element activator compound, which is a combination of linear and rotary.
Symbols hydraulic driving elements:





Activator of other elements such as cylinders, motors variable can be seen in appendix (table symbol hydraulic)


Accumulator


In hydraulic systems are sometimes necessary storage pressurized hydraulic fluid that serves as a source of pressure is required reserve a time when all of a sudden without ignoring the main pressure source (pump). Tools used to store hydraulic fluid pressure is called "accumulators".
In a hydraulic system pressurized hydraulic fluid storage serves several purposes such usage:• Increase delivery pump (saves energy)• Maintain a constant system pressure• Sources of manpower needs suddenly• Reduce surprises• Eliminate noise (noisy)• Reduce the heat expansion• Raise pressure gradually.
Accumulators are often used in the hydraulic system is the accumulator type of gas and type of spring, symbol of the hydraulic accumulator is:
















VII. Case Studies & How to Read a Hydraulic Circuit
Case 1:

if set to 120 Bar RV1, RV2 is set to 50 bar then the pressure measured / legible on Pressure Gauge (PG) is:
PG1 = ... ... ... ... Bar, PG2 = ... ... ... ... .. Bar, PG3 = ... ... ... ... ... .. Bar
Case 2:


Case 3:

Case 4:
How to Read and Hydraulic CircuitsHydraulic circuit example

Hydraulic circuit 1:




- Please list the names of the components used in the circuit- Tell me how the circulation of hydraulic fluid in the circuit, and how the system works, the hydraulic circuit of the circuit sub-system merukan what?






Hydraulic circuit 2:


- Please list the names of the components used in the circuit- Tell me how the circulation of hydraulic fluid in the circuit, and how the system works, the hydraulic circuit of the circuit sub-system merukan what?


Hydraulic circuit 3:





- Please list the names of the components used in the circuit- Tell me how the circulation of hydraulic fluid in the circuit, and how the system works, the hydraulic circuit of the circuit sub-system merukan what?











Hydraulic circuit 4:








- Please list the names of the components used in the circuit- Tell me how the circulation of hydraulic fluid in the circuit, and how the system works, the hydraulic circuit of the circuit sub-system merukan what?