APPLIED HYDRAULICS AND PNEUMATICS U5MEA23 Prepared by Mr. Jayavelu.S & Mr. Shri Harish Assistant Professor, Mechanical Department VelTech Dr.RR & Dr.SR Technical University

UNIT I : Fluid Power Systems and Fundamentals Introduction to fluid power Advantages of fluid power Application of fluid power system Types of fluid power systems, General types of fluids Properties of hydraulic fluids Fluid power symbols Basics of Hydraulics Applications of Pascal’s Law Laminar and Turbulent flow Reynolds’s number Darcy’s equation Losses in pipe, valves and fittings

Introduction to fluid power Fluid power is a term describing hydraulics and pneumatics technologi es. Both technologies use a fluid (liquid or gas) to transmit power from one location to another. hydraulics, the fluid is a liquid (usually oil), pneumatics uses a gas (usually compressed air). Both are forms of power transmission, which is the technology of converting power to a more useable form and distributing it to where it is needed. The common methods of  power transmission are electrical, mechanical, and fluid power.

Advantages of fluid power high horsepower-to-weight ratio — You could probably hold a 5-hp hydraulic motor in the palm of your hand, but a 5-hp electric motor might weight 40 lb or more. safety in hazardous environments because they are inherently spark- free and can tolerate high temperatures. force or torque can be held constant — this is unique to fluid power transmission high torque at low speed — unlike electric motors, pneumatic and hydraulic motors can produce high torque while operating at low rotational speeds. Some fluid power motors can even maintain torque at zero speed without overheating pressurized fluids can be transmitted over long distances and through complex machine configurations with only a small loss in power multi-functional control — a single hydraulic pump or air compressor can provide power to many cylinders, motors, or other actuators elimination of complicated mechanical trains of gears, chains, belts, cams, and linkages motion can be almost instantly reversed

Application of fluid power system Construction Mining Agriculture Waste Reduction Utility Equipment Marine Offshore Energy Metal Forming Machine Tools Military & Aerospace Other Applications

Types of fluid power systems Fluid transport system Transport of water from reservoir using pipe lines Transport of oil in pipe to two countries. Fluid power system Oil used in equipments to acquire desire movement. Compressed air in pneumatics for crane movements

Properties of hydraulic fluids Density The density of a fluid is its mass per unit volu me: Liquids are essentially incompressible  Density is highly variable in gases nearly prop ortional to the pressure.  Note: specific volume is defined as:

Viscosity Cohesion Adhesion Viscosity is a measure of a fluid’s resistance to flo w. It determines the fluid strain rate that is gener ated by a given applied shear stress. Cohesion Intermolecular attraction between molecules of same liquid Adhesion Attraction between molecules of liquid and molecules of solid boundary in contact with liquid.

Cavitation Capillarity Vapour pressure Cloud of vapour bubble will form when liquid pressure drops below vapour pressure due to flow phenomenon Capillarity Liquid rises into a thin glass tube above or below its general level. Vapour pressure Pressure exerted by vapour which is in equilibrium with liquid

Compatibility Volatility Corrosiveness Ability of hydraulic fluid to be compatible with the system. Volatility The degree and rate at which it will vapourize under given conditions of temperature and pressure. Corrosiveness Tendency to promote corrosion in hydraulic system.

Application of pascals law Hydraulic press

Hydraulic jack

Laminar and Turbulent flow

Reynolds number

Darcys equation

Losses in pipes, valves and fittings

UNIT 2: Hydraulic SYSTEM COMPONENTS Sources of Hydraulic Power construction and working of pumps – Variable displacement pumps Actuators: Linear hydraulic actuators Single acting and Double acting cylinders Fluid motors. Control Components: Direction control valve Flow control valves Electrical control -- solenoid valves. Relays, Accumulators and Intensifiers.

Basic Pump Classifications Hydraulic pumps can be classified using three basic aspects: Displacement Pumping motion Fluid delivery characteristics

Basic Pump Classifications Displacement relates to how the output of the pump reacts to system loads Positive-displacement pumps produce a constant output per cycle Non-positive-displacement pumps produce flow variations due to internal slippage

Basic Pump Classifications A non-positive-displacement pump has large internal clearances Allows fluid slippage in the pump Results in varying flow output as system load varies

Basic Pump Classifications Non-positive-displacement pump

Basic Pump Classifications The basic pumping motions used in hydraulic pumps are: Rotary Reciprocating

Basic Pump Classifications Gear pumps are rotary pumps Sauer-Danfoss, Ames, IA

Basic Pump Classifications Piston pumps are reciprocating pumps Reciprocating piston movement

Basic Pump Classifications In a rotary pump, the pumping action is produced by revolving components In a reciprocating pump, the rotating motion of the pump input shaft is changed to reciprocating motion, which then produces the pumping action

Basic Pump Classifications Hydraulic pumps are classified as either fixed or variable delivery Fixed-delivery pumps have pumping chambers with a volume that cannot be changed; the output is the same during each cycle In variable-delivery designs, chamber geometry may be changed to allow varying flow from the pump

Basic Pump Classifications Gear pumps are fixed-delivery pumps

Basic Pump Classifications Piston pumps may be designed as variable-delivery pumps

Basic Pump Classifications When selecting a pump for a circuit, factors that must be considered are: System operating pressure Flow rate Cycle rate Expected length of service Environmental conditions Cost

Pump Design, Operation, and Application Gear pumps are positive-displacement, fixed-delivery, rotary units Gear pumps are produced with either external or internal gear teeth configurations

Pump Design, Operation, and Application Gear pumps are commonly used

Pump Design, Operation, and Application Pumping action of gear pumps results from unmeshing and meshing of the gears As the gears unmesh in the inlet area, low pressure causes fluid to enter the pump As the pump rotates, fluid is carried to the pump discharge area When the gears mesh in the discharge area, fluid is forced out of the pump into the system

Pump Design, Operation, and Application Gear pumps are available in a wide variety of sizes Flow outputs from below 1 gpm to 150 gpm Pressure rating range up to 3000 psi

Pump Design, Operation, and Application The gerotor pump design is an internal- gear pump Uses two rotating, gear-shaped elements that form sealed chambers The chambers vary in volume as the elements rotate Fluid comes into the chambers as they are enlarging and is forced out as they decrease in size

Pump Design, Operation, and Application The gerotor is a common internal-gear design

Pump Design, Operation, and Application Gerotor operation

Pump Design, Operation, and Application Gerotor operation

Pump Design, Operation, and Application Gerotor operation

Pump Design, Operation, and Application Gerotor operation

Pump Design, Operation, and Application Vane pumps are positive-displacement, fixed or variable delivery, rotary units. Design is commonly used in industrial applications Delivery can range up to 75 gpm Maximum pressure of about 2000 psi

Pump Design, Operation, and Application Vane pump consists of a slotted rotor, fitted with moveable vanes, that rotates within a cam ring in the pump housing Rotor is off center in the ring, which creates pumping chambers that vary in volume as the pump rotates As chamber volume increases, pressure decreases, bringing fluid into the pump As volume decreases, fluid is forced out into the system

Pump Design, Operation, and Application Operation of a typical vane pump

Pump Design, Operation, and Application Parts of a typical vane pump

Pump Design, Operation, and Application Vane pump may be pressure unbalanced or pressure balanced Unbalanced has only one inlet and one discharge, which places a side load on the shaft Balanced has two inlets and two discharges opposite each other, creating a pressure balance and, therefore, no load on the shaft

Pump Design, Operation, and Application Piston pumps are positive-displacement, fixed- or variable-delivery, reciprocating units Several variations Many provide high volumetric efficiency (90%), high operating pressure (10,000 psi or higher), and high-speed operation

Pump Design, Operation, and Application A basic piston pump consists of a housing that supports a pumping mechanism and a motion-converting mechanism Pumping mechanism is a block containing cylinders fitted with pistons and valves Motion converter changes rotary to reciprocating motion via cams, eccentric ring, swash plate, or bent-axis designs Rotating the pump shaft causes piston movement that pumps the fluid

Pump Design, Operation, and Application Piston pump classification is based on the relationship between the axes of the power input shaft and piston motion Axial Radial Reciprocating

Pump Design, Operation, and Application Axial piston pumps use two design variations: Inline Bent axis

Pump Design, Operation, and Application Inline has the cylinder block and pistons located on the same axis as the pump input shaft Pistons reciprocate against a swash plate Very popular design used in many applications

Pump Design, Operation, and Application An inline axial-piston pump

Pump Design, Operation, and Application Bent axis has the cylinder block and pistons set at an angle to the input shaft Geometry of the axis angle creates piston movement Considered a more rugged pump than inline Manufactured in high flow rates and maximum operating pressures

Pump Design, Operation, and Application A bent-axis axial-piston pump

Pump Design, Operation, and Application Radial piston pumps have the highest continuous operating pressure capability of any of the pumps regularly used in hydraulic systems Models are available with operating pressure ratings in the 10,000 psi range

Pump Design, Operation, and Application Two variations of radial piston pumps: Stationary-cylinder design uses springs to hold pistons against a cam that rotates with the main shaft of the pump Rotating-cylinder design uses centrifugal force to hold pistons against a reaction ring When the main shaft is rotated, each piston reciprocates, causing fluid to move through the pump

Pump Design, Operation, and Application A stationary-cylinder radial-piston pump

Pump Design, Operation, and Application Large, reciprocating-plunger pump designs were widely used when factories had a central hydraulic power source Today, plunger pumps are typically found in special applications requiring high- pressure performance

Pump Design, Operation, and Application Screw pumps have pumping elements that consist of one, two, or three rotating screws As the screws rotate, fluid is trapped and carried along to the discharge of the pump The design of screw pumps allows them to operate at a very low noise level

Pump Design, Operation, and Application A typical screw pump

Pump Design, Operation, and Application The lobe pump is a close relative of the gear pump Two three-lobed, gear-shaped units are often used to form the pumping element Output flow is larger than a gear pump of comparable physical size because of pumping chamber geometry Lower pressure rating than gear pumps Tend to have a pulsating output flow

Pump Design, Operation, and Application Operation of a lobe pump

Pump Design, Operation, and Application Centrifugal pumps are non-positive- displacement units Use centrifugal force generated by a rotating impeller to move fluid Large clearances between the impeller and the pump housing allow internal pump slippage when resistance to fluid flow is encountered in the system Typically used in hydraulic systems as auxiliary fluid transfer pumps

Pump Design, Operation, and Application Operation of a centrifugal pump

Pump Design, Operation, and Application Propeller and jet pumps are non-positive- displacement pumps Sometimes used to transfer fluid within hydraulic systems Propeller pump consists of a rotating propeller-shaped pumping element Jet pump creates flow by pumping fluid through a nozzle concentrically located within a venturi

Pump Design, Operation, and Application Construction of a propeller pump

Pump Design, Operation, and Application Construction of a jet pump

Directional control valves Check valve Pilot operated check valve Three-way and four-way valves Manually-actuated valve Pilot actuated valve Solenoid actuated valve Center flow path configuration Shuttle valve

Directional control valves

Pilot operated check valve

Three-way valves

Four-way valves

Manually-actuated valve

Pilot actuated valve

Solenoid actuated valve

Pressure control valves Pressure relief valve Compound pressure relief valve Pressure-reducing valve

Pressure relief valve

Compound pressure relief valve

Pressure-reducing valve

Flow control valve/ Needle valve Restrictor needle valve

Weight loaded accumulator

Spring loaded accumulator

Diaphragm type accumulator

Bladder type accumulator

Intensifier

Unit 3: Pneumatic System Components Pneumatic Components: Properties of air. Compressors. FRL Unit – Air control valves, Quick exhaust valves pneumatic actuators- cylinders, air motors.

Compressor construction

Types of compressor

Piston type reciprocating compressor Fig shows single-acting piston actions in the cylinder of a reciprocating compressor. The piston is driven by a crank shaft via a connecting rod. At the top of the cylinder are a suction valve and a discharge valve. A reciprocating compressor usually has two, three, four, or six cylinders in it.

Screw compressor Screw compressors are also belong to the positive displacement compressor family. In screw compressors, the compression is accomplished by the enmeshing of two mating helically grooved rotors suitably housed in a cylinder equipped with appropriated inlet and discharge ports

Rotary vane compressor The rotor shaft is mounted eccentrically in a steel cylinder so that the rotor nearly touches the cylinder wall on one side, the two being separated only by an oil film at this point. Directly opposite this point the clearance between the rotor and the cylinder wall is maximum. Heads or end-plates are installed on the ends of the cylinder and to hold the rotor shaft. The vanes move back and forth radially in the rotor slots as they follow the contour of the cylinder wall when the rotor is turning. The vanes are held firmly against the cylinder wall by action of the centrifugal force developed by the rotating rotor. In some instances, the blades are spring-loaded to obtain a more positive seal against the cylinder wall.

Filter Air In Air Out Louver Filter Element Bowl Sight Gauge Drain Cock

Adjustable Locking Knob Regulator Adjustable Locking Knob Main Spring Diaphragm Assembly Air In Air Out Valve Spring Valve Assembly

Lubricator

Quick Exhaust Valve 2 Port 2 is connected directly to the end cover of a cylinder Port 1 receives air from the control valve Air flows past the lips of the seal to drive the cylinder When the control valve is exhausted, the seal flips to the right opening the large direct flow path Air is exhausted very rapidly from the cylinder for increased speed 2 1 1 1 2

Unit 4: FLUIDICS & PNEUMATIC CIRCUIT DESIGN Fluidics – Introduction to fluidic devices, simple circuits Introduction to Electro Hydraulic Pneumatic logic circuits, PLC applications in fluid power control, ladder diagrams Fluid Power Circuit Design: Sequential circuit design for simple applications using classic, cascade, step counter, logic with Karnaugh- Veitch Mapping and combinational circuit design methods.

Fluidics

Bistable flip flop

SRT flip flop

OR/NOR & AND/NAND

Fluidic control of pneumatic cylinders

PLC

Ladder diagram

PLC control of hydraulic circuit

Cascading circuit

UNIT 5: FLUID POWER Circuits Speed control circuits, synchronizing circuit, Pneumo hydraulic circuit, Accumulator circuits, Intensifier circuits. Servo systems – Hydro Mechanical servo systems, Electro hydraulic servo systems and proportional valves. Deceleration circuit, hydrostatics transmission circuits, control circuits for reciprocating drives in machine tools, Material handling equipments. Fluid power circuits; failure and troubleshooting.

Speed control circuit

Regenerative circuit

Pressure intensifier circuit

Accumulator circuit

Pneumatic motor circuit

Regenerative drilling machine

Hydraulic fault diagnosis

Pneumatics fault diagnosis

Thank you.