principle.components.structure.application.circuit.h118/1d HYDRAULICS principle.components.structure.application.circuit.h118/1d

Hydraulics The term “hydraulic” refers to a liquid Hydraulic systems provide a means of remotely controlling a wide range of components by transmitting a force through a confined fluid. Oil, water or other incompressible fluids were used as the means harnessing power

Pascal’s Law “Applying pressure anywhere to a body of fluid causes a force to be transmitted equally in all directions, with the force acting at right angles to any surface in contact with the fluid”

(Application: Hydraulic Lifts) Pascal’s Law Pressure = Force / Area “Since each piston has a different surface area, the force exerted on each piston will be different, even though the pressure is the same.” (Application: Hydraulic Lifts)

Hydraulics vs. Pneumatics Compressible, both in theory and in practical Hydraulics Not compressible in theory, but in practical compressible up to 0.7%

Hydraulics vs. Pneumatics ISSUES HYDRAULICS PNEUMATICS POWER Hydraulic tools are more powerful, because they use pressurized liquid (oil) Cannot deliver the same power especially when torque is required because it only uses pressurized air MAINTENANCE Very little maintenance required, as internal parts are always bathed in oil More maintenance: includes draining moisture from air tanks, and constantly keeping tools oiled NOISE Hydraulic tools are quiet Pneumatic tools are accompanied by loud compressors TEMPERATURE It will operate in sub-zero temperatures. They will not freeze up. Due to moisture in the air, pneumatic tools can freeze up COST About twice the cost of pneumatic tools Pneumatic systems is cheaper and easier to construct

Advantages of using Hydraulics Very high force despite small components Very slow and linear movements Exact positioning (stops exactly on a point) Start-up under heavy loads (because there is oil in the actuator though the pump is idling)

Components of Hydraulic System Hydraulic Power Pack Hydraulic Actuators Hydraulic Valves

Hydraulic Power Pack Pump: This supplies the oil under pressure that is required to move the system’s cylinder pistons, converting mechanical power to fluid power. Reservoir: Oil storage tank, contains HLP 22 hydraulic oil Accumulator: This is an energy storage device or reservoir for oil pressure. It must be pre-charged so they can store the oil under constant pressure when the system is not moving. Filter: Blocks away all foreign particles Pressure Gauge: For visualization Pressure Line: Connection of power pack with the circuit Return Line: Recycling oil to the tank

Hydraulic Actuators Cylinders: This converts fluid power to linear mechanical power (in rotary fluid power applications, the cylinder would be replaced by a motor). Single Acting Cylinder, Pushing Load Double Acting Cylinder, Conventional Type Double Acting Cylinder, Differential Type

Hydraulic Valves Directional Control Valve A.) 2/2 way valve (more like a shut-off valve) B.) 3/2 way valve (usually for pneumatics) C.) 4/2 way valve (usually to control Double Acting Cylinder) D.) 4/3 way valve (3 types) - 4/3 way valve, Mid position (Center) closed - 4/3 way Mid position closed valve - 4/3 way valve, Pump Bypass (Relief) Center

Hydraulic Valves Check Valve, Spring Loaded: Flow only occurs in one direction. It needs only a certain pressure to start the flow. (Non-return Valve) Pressure Relief Valve: This reduces pressure by returning oil to tank. Valve is closed in normal position. If the opening pressure is reached at the input, the output opens. When the pressure drops below the preset level, the valve closes again.

Hydraulic Valves Flow Control Valve A.) Throttle Valve (Restrictor) B.) One way flow control valve: Used to reduce the speed of cylinder movement C.) Two way flow control valve(Flow Regulator): It maintains the speed of cylinder with increased or decreased load

Hydraulic Component Symbols 4/3 way valve, Mid position (Center) closed 4/3 way valve, Pump Bypass (Relief) Center Push button spring return valve Pedal and spring return valve Lever with detent setting valve Shut-off Valve

Hydraulic Component Symbols Pressure Relief Valve Pilot controlled non-return valve Spring loaded non-return valve Throttle Valve (Restrictor) One way flow control valve

Hydraulic Component Symbols Two way flow control valve (flow regulator) Control/Pilot Line Flow Meter Reservoir

Hydraulic System

Hydraulic Applications Mobile Hydraulics - using manual hydraulic in controlling (crane, excavator, back-hoe, lifts, braking systems) Stationary Hydraulics - using electro-hydraulics in controlling (press machine, molding machine, lathe machine)

Automobile Braking System

PANEL H118/1D (HYDRAULIC COMPONENTS)

Example Hydraulic Circuits 4/3 way valve, pump bypass Flow control valve/Check Valve