Presentation on theme: "Muhajir Ab. Rahim School of Mechatronic Engineering"— Presentation transcript:
1 Muhajir Ab. Rahim School of Mechatronic Engineering Hydraulic SystemsMuhajir Ab. RahimSchool of Mechatronic Engineering
2 The Basic Hydraulic System Consist of these componentsA fluid, usually oilA tank, or reservoir, to hold a supply of fluidFluid conditioning devices to keep the fluid clean and coolA prime mover, usually an electric motor or engine, to drive the pumpA pump, to cause the fluid to flowConductors, usually pipe or tubing, to carry the fluidValving, to control fluid flow, direction and pressureOne or more actuators, usually cylinders or hydraulic motors, to do the work
4 Viscosity Viscosity is a measure of oil’s resistance to flow. It is determined under laboratory conditions by measuring the time required for a specific amount of oil at a specific temperature to flow through a small opening.The higher the viscosity, the longer it takes.High viscosity= thick, Low viscosity= thinViscosity index is a measure of how much the viscosity changes when the oil is heated.High viscosity index, if the viscosity change very little. (good quality- lubricant capability remains constant)
5 Pour, Flash and Fire Points Pour point is the lowest temperature at which a given oil will flow enough to be usefulFlash point is the temperature at which oil will flash, or light briefly if touched with a flameFire point is the temperature at which a given oil, if touched with a flame, will catch fire and stay lit for at least five seconds.The auto-ignition temperature is the level of heat at which a given oil will catch fire by itself.
6 Functions of Hydraulic Fluids Transmit force to the actuators doing work of the systemConduct heat away from moving partsLubricate moving parts to reduce heating, lessen wear, and increase efficiency
7 Desired characteristics of hydraulic fluids Appropriate viscosityLubricating abilityFreedom from damaging chemicalsResistance to foamingFire resistanceOxidation resistance*Additives are used to achieve desired characteristics in hydraulic fluid
8 Contaminants Contaminants in hydraulic fluid are a major source of problems in system operationThe three principle sources of contaminants are;Newly installed componentsAir entering the tankSystem operation, generating chemicals, gum, sludge, varnish and moisture
9 Hydraulic Reservoir (Tank) The functions of a tank areStore fluidProtect fluidProvide means for checking fluid levelProvide means for adding fluidCoolingRemove contaminants
11 Strainer is used to block large contaminant particles from entering the system Baffle is a wall in the tank, to disrupt the flow between return line and pump inlet line (for more even fluid temperature and more thorough settling of contaminants to the tank bottom)Magnetic plug is used to attract metal particles. (should be removed and cleaned periodically)
12 Tank Schematic Diagram Tank with immersed strainerTank with strainer in pump inlet lineTank with strainer in pump inlet line, filter in returnTank with pump inlet line
13 Pump The purpose of pump is to cause fluid flow The motor or engine that drives a pump is called a prime moverThe most common type of pump is the external gear pumpPositive-displacement pumps mean that fluid must be moved when the pump is running
15 Pump Schematic Diagram MOTORSTRAINERTANKSystem schematic showing location of the pump and motor
16 Pressure Relief Valves A pressure relief valvehas two functions:Set a maximum operating pressure level for the systemProtect system components such as the pump, valves, and lines from overpressure.
17 System schematic showing location of the pressure relief valve PUMPPRESSURE RELIEF VALVEMOTORSTRAINERTANKSystem schematic showing location of the pressure relief valve
18 Pressure Reducing Valve The purpose of pressure reducing valve is to regulate or limit pressure for an individual circuit branch or actuator
19 M System schematic showing location of the pressure reducing valve PUMPPRESSURE RELIEF VALVEMOTORSTRAINERTANKSystem schematic showing location of the pressure reducing valve
20 Directional Control Valve The purpose of directional control valve is to deliver fluid to an actuator at the proper port at the appropriate time.A way is a flow path through a valve.A port is an opening in the valve body.A position is a specific setting of a spool which determines flow paths.Directional control valves are described by specifying the number of ways, the number of positions, the means by which the valve is operated, and for 3-ways valves, whether open or closed center.
22 PRESSURE REDUCING VALVE DIRECTIONAL CONTROL VALVE MPUMPDIRECTIONAL CONTROL VALVEMOTORPRESSURE RELIEF VALVESTRAINERACTUATORTANKSystem schematic showing location of the directional control valve and actuator
23 ActuatorDevice which converts fluid energy into mechanical force and motion.Cylinder is used to produce motion in a straight line, which we call linear motion.Rotary actuator (hydraulic motor) is used to convert hydraulic energy into rotating motion about an axis.
25 Quiz A hydraulic system is said to have a mechanical advantage of 40. If the input piston, with a12 inch radius, has a force of 65 pounds pushingdownward a distance of 20 inches, findi. the volume of fluid that has been displacedii. the upward force on the output pistoniii. the radius of the output pistoniv. the distance the output piston moves