HYDRAULIC SYSTEM AND HYDRAULIC PUMP

Hydraulic Systems

The hydraulic system is an energy transfer system using liquid or fluid as an intermediary. The hydraulic system has many advantages than using mechanical systems.

The advantages are as follows:

a.        Can distribute torque and great style

b.       Prevention of overload is not difficult

c.        Control style is easy and fast operation.

d.       Easier speeds Substitution

e.        Vibrations arising relatively smaller

f.        Longer durability.

However, this hydraulic system also has some drawbacks, namely:

a.        Sensitive to leak

b.       Sensitive to changes in temperature

c.        Sometimes changing work pace

d.       Work-channel system is not simple.

 Hydraulic divided into 2 parts:

a.        Hydrodynamics: the Science of LEARNING about moving liquid

b.       Hydrostatic: Science is the study of pressurized liquid 
On hydrostatic is the opposite of the hydrodynamics of liquid that is used as a medium power, switching liquid yield and liquid movement is in a closed tube

Pressure and Style

To cause the fluid pressure must be compressed. Amount of fluid is compressed and pressure values ​​depend on the style used to drain the fluid and stylish styles that inhibit (resisting) fluid flow.

Hydraulic pump causes fluid flow and resisting movements caused by hydraulic circuits.

Things that cause fluid flow is obstructed:

a. Cylinder piston load, the greater the load the greater the required pressure.

b. If there is a back pressure, the flow will be hampered.

c. Existing hydraulic circuit, hose, valves, fittings, filters and orifice will cause friction and difficult to drain fluid.

Note: Friction flow will be even greater if:

- Increased length of pipe or hose

- Speed ​​oil

- Reduced the size of the diameter of the channel.

- Reduced for oil temperature

Pressure and Style

• If a liquid under pressure then the liquid will always flow through the easiest way

• Due to the nature of the liquid above is a weakness because it can damage the system, for example:

a.        Leaks in the fittings loose

b.       Seal-seal leaks in the damaged

Hydraulic Fluid

In the hydraulic system, which is commonly used fluid is oil. Oil commonly used are:

a.        Engine oil (Engine oil)

b.       Hydraulic oil (hydraulic oil)

Engine Oil (Engine Oil)

Thickness (viscosity)

Engine oil viscosity is expressed in the SAE (Society of Automotive Engineering) where greater numbers mean the engine oil more viscous. Example SAE 10, SAE 20, SAE 30.

Engine oil classification stated in the API (American Petroleum Institute), in which case the higher end of the oil the better classification.

Example: 
Diesel engine for CA, CB, CC, CD

For gasoline engines: SA, SB, SC, SD, SE, SF

Hydraulic Oil

In the hydraulic oil has a viscosity and classification as engine oil, not only expressed in the SAE and API service code.

Nature of the oil in the hydraulic system:

a.        Can not be compressed (uncrompressible).

b.       Are easily flow (fluidity).

c.        Must be stable physical and chemical properties.

d.       Has properties lubricate.

e.        Prevent rust.

f.        Is easy to adjust with the place.

g.       Can separate poo poo.

Hydraulic fluid functions:

According to the principle of Pascal's power transmission, hydraulic power is the product of the transmission (pressure) force with the flow PQ/60 KW

Prevent friction wear and lubrication of components 
Close the oil viscosity will help close the gap between components. 
Prevents cool the heat, excessive heat caused by wear and tear, loss of pressure, internal leakage.

Damage Oli.

The use of hydraulic oil should be kept from destruction, because the hydraulic oil can cause damage that is not working most out of the unit. Here are some of the causes of damage to oil:

o Contamination (Contamination)

Namely damage caused by the fault of outside influence or outside the oil.

o deterioration (deterioration)

Ie oil damage caused by the influence of the oil itself 
Further shown in the following figure disturbance disturbance if oil were damaged.

Components, Symbols and Diagrams Hydraulic

Hydraulic components in the system transfer power to the hydraulic system is very important to know the functions and how it works. Hydraulic symbol symbol readability is very simple but very complete and representative in accordance with the actual working components.

  For example the pump symbol, the symbol is drawn exactly the way the pump is actually working.

Components and Symbols

a. Hydraulic Tank / Hydraulic Reservoir

The hydraulic tank oil container to be used in hydraulic systems. 
Oil heat is returned from the system / actuator cooled by spreading the heat. And use as an oil cooler oil cooler, then back into the tank

Air bubbles from the oil fill spaces above the surface of the oil oli.Untuk maintain good condition during engine operation, equipped with a filter that aims not to go back to dirt tank.

Hydraulic tanks are classified as Type Vented reservoir or reservoir pressure, the pressure in the tank, the entry of dust from the air will be reduced and the oil will be forced into the pump.

b. Pump

Hydraulic pump function in the human body such as the heart is pumping blood as

Hydraulic pump is a component of the hydraulic system that makes oil flow or hydraulic pump as a source of mechanical energy that turns power into hydraulic power.

  Classification of pumps

Non Positive Displacement Pump: has a baffle between the inlet / outlet ports and inlet / out port, so that the liquid can flow in the pump if there is pressure.

Example: The water pump also includes so-called non-positive type diplasement. 
Positive diplacement pump: Having the inlet / outlet ports and inlet / outlet ports on the bulkhead at the pump.So this type of pump can work with very high pressure and must be in protection against excessive pressure by using a pressure relief valve.

Example: Hydraulic Pump heavy equipment

Fixed displacement pump: pump has a chamber with a fixed volume (fixed volume pumping chamber) Out putnya can only be changed by changing the speed of work (drive speed)

Variable displacement pump: the pump chamber volume has varied, the output can be changed by changing the displacement or the drive speed, fixed displacement pump and variable pump used on earthmoving equipment

d. Motor

Symbol for Fixed displacement motors is a circle with a triangle in it.

Pump has a triangle symbol that indicates the direction of flow., And the motor has a triangular symbols that point to the symbol for a single element pump / motor that also includes a reversible have two triangles in a circle, each showing the direction of flow. 
A variable displacement pump / motors are shown as symbols mark base with crossed arrows depicted

d. Channel Hose, Pipe

  There are three major kinds of lines used in the depiction of graphic symbol to symbolize pipes, hoses and lines in relation to the hydraulic components

Splid digunkan line represents the hydraulic pipework. Pipework is channeling the main flow of oil in a hydraulic system.

Dashed line is used to control the hydraulic pipes mlambangkan. The pipeline control channel tiny amounts of oil that is used as a flow aid for moving or controlling the hydraulic components.

An illustration graphic symbol consisting of line work, line control and exhaust line intersect.

The intersection in the draw with a half-circle at the point of intersection between the lines with a line line, or a line described as two mutually bepotongan.

Relationship between the two lines can not be expected unless noted with a connecting point

. Liaison point is used to show an illustration of where the lines touch.

 If the connection occurs in the form of T, a connecting point can be ignored because the relationship line between the two lines are clearly visible.

When shown a certain flow direction, arrowheads mark can be added to the line in the picture that shows the direction of oil flow

e. Hydraulic Cylinders

Hydraulic cylinder liquid energy change into mechanical energy. Fluid pressure, pressing the piston side of the cylinder to move a mechanical movement.

Singgle acting cylinder only has one port, so it only makes pressurized fluid through the channel, and push in one direction. This cylinder to reverse the movement by opening a valve or due to the force of gravity or also the power of spring.

  Double acting cylinder has a port on each side so that the bias pressure fluid entering through the two halves so that bias does two piston movement.

Cylinder movement speed depends on fluid flow rate (gallons / minute) and also the volume of the piston.

  Cycle time is the time required by a hydraulic cylinder for moving the full stretching. Cycle time is very important in diagnosing hydraulic problem.

  Volume = Area x Stroke

CYCLE TIME = (Volume / Flow Rate) x 60

f. Pressure Control Valve

Hydraulic pressure is controlled through the use of a valve that opens and closes at different times based on fluid flow by-pass from the high pressure to lower pressure. The arrows show the direction of oil flow.Pressure control valve is usually the type of pilot, which works automatically by hydraulic pressure, not by human. Pilot oil retained by a spring biased normally be adjusted. The greater the spring tension, the greater the fluid pressure required to move the valve.

g. Pressure Relief Valve

Presure Relief Valve to limit the maximum pressure in the hydraulic circuit to limit the maximum pressure on the components in the circuit and the outside circuit from excessive pressure and damage to components.

When Presure relief valve open, high-pressure oil is returned to the reservoir at low pressure. Presure relief valve is usually located in the directional control valve.

There are two kinds of relief valves that are used are:

Direct Acting Relief Valve is using a strong spring to hold back the flow and open when the pressure is greater than hidrlik Pilot Operated spring pressure relief valve that uses spring pressure and oil pressure relief valve to run and is a more common type used

h. Directional Controll Valve.

Hydraulic fluid flow can be controlled by using a valve which only provide one-way flow. This valve is often called the check valve system that generally uses the ball.

Symbols directional control valve there is a combination of several symbols. The valve consists of parts into a block or also with a separate block. Dashed lines show the pilot pressure drop. The pressure pilot line will connect or disconnect valve depends on the type of valve is normaly closed or normally open.

Spring serves to condition the valve in the normal position. If the pressure is build up on the valve side flow, the channel will be hit and the pilot valve opens. When the pressure has dropped back then spring will return to its original position helped pilot line pasa other side so that the flow will be interrupted. This valve is also commonly used as a flow divider or as a flow control valve.

 i. Flow Control Valve

Function of the flow control valve is to control the direction of movement of the hydraulic cylinder or hydraulic motor to change the direction of the flow of oil or cut off the oil.

Flow control valve there are various kinds, depending on how many positions, for example:

Flow control valve two position normally used to regulate the flow to the actuator in a simple hydraulic system.

Flow control valve symbol symbol below shows some kind of way of operation, there is the use of the handle, pedal, solenoid, and so forth.

j. Flow Control Mechanis

There are times when the hydraulic system requires a decrease in the flow rate or lower oil pressures at some point in the system. This can be done by installing a restrictor. Restrictor described as a diminution in the system, can be fixed as well as variable, bahakan bias is controlled by another system.

k. Symbols pengkodisian liquid

Pengkodisian oil can be done in various ways, usually in the form of filters, heating and cooling.

There are 2 types of filters commonly used are:

Strainer 
Made of fine mesh screen that size.

This filter only separates coarse particles that are in the oil.

This filter is usually installed in the reservoir tank at the inlet to the pump.

Filter:

Made of special paper.

This filter separates fine particles that exist in the oil 
This filter is usually contained in the return line to the reservoir tank 
Hydraulic Oil filter tasks

Sifting dirt, metal particles, etc..

Droppings can cause rapid wear of the Oil Pump, Cylinder and Valve Hydrlic.

Fine sieve that filters will become clogged gradually in line with the hours of operation of the machine, then the element needs to be replaced periodically.

Equipped with a bypass valve so that if the filter clogged, oil may escape the filter and back into the tank. This may prevent the occurrence of excessive pressure and damage to the system.

l. Accumulator

Accumulator function as shock absorbers in the system. Usually accumulator mounted parallel with the pump and other components. Accumulators provide a bit streams in an emergency on the steering system and brakes, maintaining constant pressure in other words as a pressure damper. Commonly used in modern hydraulic system accumulator with the type of gas.

The workings of Hydraulic Systems

1.       Hydraulic pressure using a pump (gear pump piston pump # 4) in the hydraulic tank is driven by a motor which is mounted vertically above the hydraulic tank .

2.         Hydraulic oil is driven by Radial Piston Pump (4) through a Check Valve (9) the function for hydraulic oil does not return to the vacuum pump toward Pressure Control Valve / Relief Valve (No. 7) through Four Way Ball Valve 2 -Manifold Block (No. 5).

3.         Hydraulic oil inside the Pressure Control Valve can be set manually by a Hand Control Valve (6), the function   set by hand to the forward position and the hydraulic cylinder   backward, forward and backward when the automated system can not work anymore or damaged.

4.       Oil pressure in the Pressure Control Valve (7) combined with an Unloading Solenoid Valve (8) is mounted on Manifold Block (5) got an order from Amplifier Card (Relay Control) to open the valve when the load screw press up and close it when the load screw press down, so that the axis of the cylinder can be back and forth according to the load on the amplifier tuned card (relay control) that can detect ampere screw press through a CT installed in the starter box.

5.       Cylinder   Hydraulic has   two connection lines, one in front and one behind. Oil pressure   go to the front lines, hydraulic recoil cylinder axis, and the axis of the rear entrance to the hydraulic lines forward.

6.         Hydraulic oil can be automatically and regularly circulated by the hydraulic pump to the hydraulic tank, cooled through an intergral Oil Cooler (17), and then filtered by a Return Line Filter (12). Hydraulic oil must be kept clean and not diminished.

7.       To add (or decrease) the hydraulic pressure can be opened by turning the screw located on the Pressure Control Valve / Relief Valve (7) gradually until it reaches 45 bar. To find out how much oil pressure can view pointer at PressureGauge (11).Pressure Control Valve / Relief Valve (# 7) and SolenoidUnloading Valve (11) serves to regulate the flow of hydraulic pressure to the cylinder, and Shut Off Valve (10) which serves to close the pressure hidrolikke Pressure Gauge (11) .  

8.       Height and temperature of the hydraulic oil level in the tank can be seen in the Fluid Level Gauge (15).

9.       Operation of the hydraulic system of the above, if you prefer Electro Hydraulic Motor (2) can stop working at a certain pressure and running again when work pressure is reduced, then it must be installed for a Pressure Switch.

10.   To stabilize the working pressure in order to keep an electro motor stopped, must be installed accumulator (integral oil cooler 17 excluded). (Note: no hydraulic system accumulator above, work pressure as well as stable and constant hydraulic pumps still work).

11.     (Point 9 and 10 above) With the use of switches and accumulator pressure in the hydraulic system so that the electric motors and hydraulic pump can be stopped for a while (5-30 seconds) is not efficient because maintenance costs are expensive and do not get the results accordingly.

The electric motors and hydraulic pumps always preformance is ON / OFF immediately because teralu ampere load and high heat so flammable.

Pump is driven via a flexible coupling always plucked by the ON / OFF electric motors, the gear and piston pumps perishables and Sompel.

Treatment can not be done alone accumulator after diving operation 1-2 years, due to be repeated with nitrogen gas every year with special syringe-charging kit.

Classification of Hydraulic Pumps

All pumps cause flow (flow). The principle of operation is called displacement, "in which a liquid or fluid is taken and transferred to another place. In general, pumps convert mechanical energy into hydraulic fluid power. While the definition of displacement is the volume of liquid displaced per cycle (rotation) of the pump.

Pump classification.     

Hirolik pump basically classified into:

a. Non positive displacement

What is meant by positive displacement pumps NON is when the pump has the following characteristics:

1.       Large internal leakage.

2.       Pressure changes have a significant influence on its capacity      

b. Positive displacement.

What is meant by positive displacement pump when the pump is to have the following characteristics:

1.       Small internal leakage (to get this made ​​SEAL or precision).

2.       Small pressure changes affect the capacity (with a precision made ​​/ SEAL, going against leakage when the pressure rises).

Positive displacement pumps are divided into several types, namely:  

·          Gear pump: is cheap, has a long durability (durable), simple operation. But its weakness is to have low efficiency, because of the nature of air-displacement pump that fixed, and more suitable for use at pressures below 20 MPa (3000 psi).  

·          Vane pump: cheap and simple, low maintenance costs, and better to produce high flow at low pressure.

·          Axial piston pump. One interesting type of hydraulic pump is axial piston pump. This pump can also typeswashplate or checkball. This type of pump is designed to be belerja the displacement varied, so as to produce a flow and pressure of hydraulic fluid which varies according to the needs. The most widely used type is the swashplate pump. These pumps can we change the angle of the swashplate piston to produce measures that vary each round. If the angle of the semakina, will produce a large flow rate with the pressure of the smaller, and vice versa.  

·          Radial Piston Pump: used to generate high pressure hydraulic fluid at low flow rates.