The document provides an overview of hydraulic systems and their components. It explains that hydraulics uses confined liquids under pressure to transmit force and motion. The key components of a basic hydraulic system are a tank to store fluid, a pump to create flow, actuators to do work, control valves to direct flow, and relief valves to regulate pressure. Together these components form closed circuits where fluid is pumped from the tank through valves and actuators and returned to the tank, with filters used to keep the fluid clean.
The document provides an overview of hydraulic systems and their components. It explains that hydraulics uses confined liquids under pressure to transmit force and motion. The key components of a basic hydraulic system are a tank to store fluid, a pump to create flow, actuators to do work, control valves to direct flow, and relief valves to regulate pressure. Together these components form closed circuits where fluid is pumped from the tank through valves and actuators and returned to the tank, with filters used to keep the fluid clean.
The document provides an overview of hydraulic systems and their components. It explains that hydraulics uses confined liquids under pressure to transmit force and motion. The key components of a basic hydraulic system are a tank to store fluid, a pump to create flow, actuators to do work, control valves to direct flow, and relief valves to regulate pressure. Together these components form closed circuits where fluid is pumped from the tank through valves and actuators and returned to the tank, with filters used to keep the fluid clean.
The document provides an overview of hydraulic systems and their components. It explains that hydraulics uses confined liquids under pressure to transmit force and motion. The key components of a basic hydraulic system are a tank to store fluid, a pump to create flow, actuators to do work, control valves to direct flow, and relief valves to regulate pressure. Together these components form closed circuits where fluid is pumped from the tank through valves and actuators and returned to the tank, with filters used to keep the fluid clean.
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Construction & Mining Technique
Atlas Copco Wagner Inc.
Division Construction & Mining Technique Basic Hydraulics Fluid Power System Fluid Power Systems are power transmitting assemblies employing pressurised liquid or gas to transmit energy.
Fluid power can be divided into two basic disciplines
> Hydraulics Employing pressurised liquid
> Pneumatics - Employing compressed gas What is Hydraulic? Hydraulics is derived from the Greek word
- Hydor meaning Water
- Aulos meaning Pipe Definition of Hydraulic In simple language:
Confined liquids under pressure made to do work. OR Science of transmitting force / motion through the medium of confined liquid Definition of Hydraulic Hydraulics can be divided in to two Sciences :
Hydrodynamic : The science of moving liquid. The kinetic energy of the moving fluid is used to do work. Water wheel / Turbine is the example.
Hydrostatics : The science of confined liquid under pressure. The force generated due to creation of pressure on confined liquid is used to do work. Hydraulic cylinders is the example. Pascal Law Hydraulic system is based on Pascals law.
Pressure applied on a confined fluid is transmitted in all directions and acts with equal force on all equal areas and at right angles to them
Pascal Law was named after the French Scientist Blaise Pascal
Pascals Law - illustration Hydraulic Press working principle Realising that a small force on a small area would create a proportionately larger force on a larger area, a British mechanic named Joseph Bramah applied Pascals Law in developing an Hydraulic Press. Hydraulic Press working principle Variable speed : Possible to control speed through valve. Reversible : Instant reverse motion is possible. No need to stop the system to change direction. Over load protection : Protected through relief valve from over- loading. Small package : Components are smaller than other power transmitting system. Can be stalled : Not possible on direct drive system from Electric motor / Diesel engine. Simple design : Pre-engineered components available. Self lubricated : Hydraulic oil lubricates the parts. Flexible : Flexible hoses virtually eliminate the location problem of the hydraulic components. Smooth : Incompressible, no vibration. Acts as coolant : It dissipates heat / cools the component, Acts as seal ; It seals clearances between two mating parts. Noise free : No noise. Advantages of oil in Hydraulics Functions of Hydraulic Oil It transmits power.
It lubricates moving parts
It seals clearances between moving parts
It dissipates heat Hydraulic System Reservoir
Filter
Hydraulic Pump
Directional Control Valve
Pressure Control Valve
Actuator (Cylinder/Motor) Tank / Reservoir First a tank is needed to store the hydraulic oil Reservoir Reservoir Storing oil
Compensates difference in volume when actuators are used
It dissipates heat
It allows foreign particles to settle down
Baffle separates inlet line with the return line and allows the air bubbles to escape to the surface of the oil Reservoir It allows condensed water to settle at the bottom of the tank
Breather on the top of the tank allows to maintain atmospheric pressure and avoid creation of vacuum
Sight glass will indicate the level of the oil. Mercury bulb in it will indicate the oil temperature
Oil filling inlet will have a filter for avoiding contamination.
Tank Pump Now we need a pump to create flow Pump Pump Hydraulic Pump is the most important component in the hydraulic system.
Function of the Hydraulic Pump is to convert Mechanical Energy to Hydraulic Energy
Hydraulic Pump are classified in two catagories:
- Hydro-dynamic
- Hydro-static Pump Two types of hydraulic pumps are most commonly used:
- Rotary Pumps
- Reciprocating Pumps Rotary Pumps Common Pumps in Rotary type are:
- Gear Pumps
- Vane Pumps Reciprocating Pumps Common Pumps in Reciprocating type are:
- Axial Piston Pump
- Radial Piston Pump
Tank Pump Actuator The Actuator (Motor / Cylinder) to work Actuators Actuators There are mainly two types of Actuators:
- Linear actuators (single acting cylinders, double acting cylinders)
- Rotary actuators (vane motors, gear motors, piston motors etc.) Tank Pump Actuator Piston reverse movement is not possible We need a direction control valve to change the direction of flow as per requirement Hoses to connect the components Hydraulic System Tank Pump Actuator Direction Control Valve Hydraulic System Valves Valves are components which guide hydraulic oil delivered by the Pump to the actuators.
Valves regulate the hydraulic oils
- Volume rate of flow
- Pressure
- Direction Valves design There are mainly two design principles for valves
- Spool valves
- Poppet valves Types of Valves There are three main types of Valves:
- Flow Control Valves (needle valve, throttle check valve etc.) Two way Spool valve Spool type Four way valve Pressure Close - A & B open to tank A & B Close - Pressure open to tank Three position Valve Variable restrictor type Flow control valve Simple Poppet type Check valve Pilot operated check valve Shuttle valve Tank Pump Actuator Direction Control Valve The control valve is at neutral position Hydraulic System Tank Pump Actuator Direction Control Valve Now the control valve is shifted to left Hydraulic System Tank Pump Actuator Direction Control Valve To change the piston movement in opposite direction the control valve is now shifted to right Hydraulic System Tank Pump Actuator Direction Control Valve Is it complete circuit ? OR We need some thing more Hydraulic System Tank Pump Actuator Direction Control Valve Piston at end - No room to move Pressure increases yes We need some thing more We need to control the system pressure Hydraulic System Tank Pump Actuator Direction Control Valve Pressure relief valve Hydraulic System Tank Pump Actuator Direction Control Valve Pressure relief valve Hydraulic System Tank Pump Actuator Direction Control Valve Stops pressure increasing beyond the preset value Pressure relief valve Hydraulic System Direct acting Relief valve Tank Pump Actuator Direction Control Valve Now we have a system which can work But is this system protected from dirt!!!! Pressure relief valve Hydraulic System Tank Pump Actuator Direction Control Valve We need to protect the system from dirt by installing a FILTER in the system Filter We have a system now which can work safely Pressure relief valve Hydraulic System Is filtration necessary? Impurities in the Hydraulic system affect the the components of the hydraulic system and shorten the service life.
Reduction in service life of the components occur in two ways
- Wear and Tear
- Breakdown of component
Filters are used to remove the smallest insoluble particles and keep the hydraulic system clean Filters There are basically three types of Filters
- Suction line filters
- Pressure line filters
- Return line filters Tank Pump Actuator Direction Control Valve Filter Now we know : Tank contains oil Filter cleans the system Pump creates flow Resistance creates pressure Actuator to perform the work Hoses to transmit the oil D.C. Valve to change direction of oil flow Relief valve to control the maximum system pressure.
Pressure relief valve Hydraulic System Tank Pump Actuator Direction Control Valve Filter Few more facts : Pressure increases the system capacity Flow increases the system speed
Pressure relief valve Hydraulic System Hydraulic jack LOAD OIL Hydraulic System