BASIC HYDRAULICS

What is Hydraulics?

• Hydraulics is derived from the Greek word

- Hydor meaning Water

- Aulos meaning Pipe

Hydraulic System• Means of transmitting energy from one

area to another efficiently

• Energy transmitted can be divided into two basic disciplines

> Hydraulics – Employing pressurized liquid

> Pneumatics - Employing Compressed gas

• We would be only be discussing hydraulics i.e. fluid mechanics

HYDRAULICS DEFINED FURTHER…

Fluid Mechanics is the physical science and technology of the static and dynamic behavior of fluids.

• Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties.

PASCAL’S LAWPascal Law – which is the basis for all hydraulic systems, is named after the French Scientist – Blaise Pascal, who established the law.

Pascal’s LawPascal’s LawIt states that “ Pressure exerted anywhere in a confined It states that “ Pressure exerted anywhere in a confined fluid is transmitted equally in all directions throughout the fluid is transmitted equally in all directions throughout the fluid.f luid.

• The basic idea behind all hydraulic system is based upon that The basic idea behind all hydraulic system is based upon that principle & can be simply stated as: principle & can be simply stated as:

• Force applied at one point is transmitted to another point Force applied at one point is transmitted to another point using an using an incompressible f luid.incompressible f luid.

Working Principle of a Hydraulic Working Principle of a Hydraulic PressurePressure

Functions of Hydraulic OilFunctions of Hydraulic Oil• It transmits power.It transmits power.

• It lubricates moving partsIt lubricates moving parts

• It seals clearances It seals clearances between moving partsbetween moving parts

• It dissipates heat i.e. It dissipates heat i.e. cooling purposescooling purposes

Force that is applied at one point is Force that is applied at one point is transmitted to another point using an transmitted to another point using an incompressible fluidincompressible fluid • In this drawing, two pistons (green) fit into two glass In this drawing, two pistons (green) fit into two glass

cylinders filled with oil (blue) and connected to one cylinders filled with oil (blue) and connected to one another with an oil-filled pipe. If you apply a downward another with an oil-filled pipe. If you apply a downward force to one piston (the left one in this drawing), then the force to one piston (the left one in this drawing), then the force is transmitted to the second piston through the oil force is transmitted to the second piston through the oil in the pipe in the pipe

Hydraulic System PartsHydraulic System Parts• Reservoir/TankReservoir/Tank

• AccumulatorAccumulator

• FilterFilter

• Hydraulic PumpHydraulic Pump

• Directional Control ValveDirectional Control Valve

• Pressure Control ValvePressure Control Valve

• Actuator (Cylinder/Motor)Actuator (Cylinder/Motor)

Tank / Reservoir

First a tank is needed to store the hydraulic oil Reservoir/Tank- Properties

Storing oil

I t dissipates heat

It al lows foreign part icles to sett le down

Baff le separates inlet l ine with the return l ine and al lows the air bubbles to escape

AccumulatorAccumulator

• Absorbs the shocks due to rapid pressure Absorbs the shocks due to rapid pressure variations in a hydraulic systemvariations in a hydraulic system

• Helps maintain constant pressure within Helps maintain constant pressure within hydraulic systemhydraulic system

• Can be used as an emergency source of Can be used as an emergency source of powerpower

PUMPSPUMPS

• Hydraulic Pump is the most important Hydraulic Pump is the most important component in the hydraulic system.component in the hydraulic system.

• Function of the Hydraulic Pump is to convert Function of the Hydraulic Pump is to convert Mechanical Energy to Hydraulic EnergyMechanical Energy to Hydraulic Energy

• Hydraulic Pump are classif ied in two Hydraulic Pump are classif ied in two categories:categories:

- Hydro-dynamic- Hydro-dynamic

- Hydro-stat ic- Hydro-stat ic

Tank

Pump

Now we need a pump to create flow

Pump

Two types of hydraulic pumps are most commonly used:

- Rotary Pumps

- Reciprocating Pumps

ROTARY & RECIPROCATING ROTARY & RECIPROCATING TYPESTYPES• Common Pumps in Rotary type are:Common Pumps in Rotary type are:

- Gear Pumps- Gear Pumps- Vane Pumps- Vane Pumps

• Reciprocating type is given by:Reciprocating type is given by:

ACTUATORSACTUATORS

• An actuator is a mechanical device for An actuator is a mechanical device for moving or controlling a mechanism or moving or controlling a mechanism or system. An actuator typically is a system. An actuator typically is a mechanical device that takes energy & mechanical device that takes energy & converts it to a desirable form for usage or converts it to a desirable form for usage or application.application.

Actuator

Pump

Tank

ACTUATORS Contd…ACTUATORS Contd…

• There are mainly two types of There are mainly two types of Actuators:Actuators:

- Linear actuators - Linear actuators Used to operate trail ing edge flaps, tr im tabs, elevator, Used to operate trail ing edge flaps, tr im tabs, elevator, rudder, aileron etc.rudder, aileron etc.

- Rotary actuators- Rotary actuatorsUsed in air conditioning, landing gears and fuel Used in air conditioning, landing gears and fuel

systemssystems

Types of ValvesTypes of Valves• There are three main types of There are three main types of

Valves:Valves:

- Pressure Control Valves (relief - Pressure Control Valves (relief valves, pressure regulating valve, valves, pressure regulating valve, pressure reducing valve)pressure reducing valve)

- Directional Control Valves (check - Directional Control Valves (check valve)valve)

- Flow Control Valves (needle valve, - Flow Control Valves (needle valve, thrott le check valve etc.)thrott le check valve etc.)

Relief valveRelief valve

• This is simply a pressure relief valve. If a This is simply a pressure relief valve. If a malfunction in the system causes the malfunction in the system causes the pressure to rise too high, the relief valve pressure to rise too high, the relief valve opens and the fluid simply passes back to opens and the fluid simply passes back to the reservoir. In virtually all automotive the reservoir. In virtually all automotive power steering pumps, the relief valve is power steering pumps, the relief valve is built into the pump built into the pump

Tank

Pump

Actuator

Hydraulic System – some applications of the basic components

FILTERSFILTERS

• There are basically three There are basically three types of Filterstypes of Filters

- Suction l ine fi l ters- Suction l ine fi l ters

- Pressure l ine fi l ters- Pressure l ine fi l ters

- Return l ine fi l ters- Return l ine fi l ters

Why is filtration necessary?Why is filtration necessary?• Impurit ies in the Hydraulic Impurit ies in the Hydraulic

system affect the components system affect the components of the hydraulic system and of the hydraulic system and shorten their service l i fe.shorten their service l i fe.

• Reduction in service l i fe of the Reduction in service l i fe of the components occurs in two components occurs in two ways:ways:- Wear and Tear- Wear and Tear- Breakdown of component- Breakdown of component

Filters are used to remove the Filters are used to remove the smallest insoluble particles smallest insoluble particles and keep the hydraulic system and keep the hydraulic system clean clean

Devices Employing Hydraulic Devices Employing Hydraulic System in AircraftsSystem in Aircrafts• Landing gearsLanding gears• Fuel systemsFuel systems• Air conditioningAir conditioning• Control Surfaces e.g. elevators, flaps, spoilers, ailerons Control Surfaces e.g. elevators, flaps, spoilers, ailerons

etc.etc.• Doors and hatchwaysDoors and hatchways• Shock absorption systemsShock absorption systems• Bomb bay doorsBomb bay doors• Gun turretsGun turrets• Auto pilotAuto pilot

Some Hydraulic SymbolsSome Hydraulic Symbols

SO, IN HYDRAULICS, AS IN LIFE, SO, IN HYDRAULICS, AS IN LIFE, REMEMBER YOUR BASICS & NEVER REMEMBER YOUR BASICS & NEVER

GIVE UPGIVE UP

AND LIFE SHALL BE FULL OF AND LIFE SHALL BE FULL OF HAPPINESSHAPPINESS