Hydraulic Systems PDF

# Chp. 1 * Intro: All machines require a type of power source & a way of transmitting this power to the operational point. * Power transmission methods - Mechanical, Electrical & Fluid. * Fluid Power - A method of using pressurized fluid (liq, gas) to transmit energy. * Hydraulic - Transmission of...

# Chp. 1 * Intro: All machines require a type of power source & a way of transmitting this power to the operational point. * Power transmission methods - Mechanical, Electrical & Fluid. * Fluid Power - A method of using pressurized fluid (liq, gas) to transmit energy. * Hydraulic - Transmission of power from a power generation source to a sink, using incompressible hydraulic fluid for creating motion. * Used where req large forces & precise control. * Such as: Vehicle power steering, brakes, hydraulic Jacks, heavy earth moving machines. * Hydraulic system works on the principle of Pascal's Law. * Pneumatic - Transmission of power from a power generation source to a sink, using compressible air for creating motion. * Air is compressible - It's possible to force an object into a smaller space, such as: sponge, it can be squeezed into a smaller size. * Liquid is incompressible - unable to force an object into a smaller size. * Pascal law - The pressure exerted at one surface of an incompressible fluid is equd to the pressure exerted on other surface, this allows a small force applied to a small area to be converted to a large force, applied to a large area. * Such as: hydraulic lift. ## Applications of Hydraulic system | Industrial | Mobility | Automobile | Manne | Aerospace | |---|---|---|---|---| | Transfer lines | Tractors | Brackes | Coversmoceom | Brackes | | Presses | Irrigation | Steering, clearing | Vessels, bouts | Landing geens | | Lifts | Rail & earth moving | Wind shield & shock absorber | | Flight controllers | | Rolling lines | Material handling & drilling rigs | | | | | Production & Assembly machines | | | | | | Injection molding machines | | | | | ### Advantages 1. Incompressible fluid - high [n] & high density. 2. Const power output, which's difficult pneumatic or mechanical drive systems. 3. Low maintenance cost. 4. Low Possibility of leakage. 5. Suitable for hot environment conditions. ### Disadvantages 1. Material of storage tank, piping, cylinder & piston can be corroded with hyd. fluid, so it's very important to select the suitable material & fluid. 2. High structural weight & size, there are unsuitable for small instruments. 3. The small impurities in fluid can damage the complete system, so it's important to select the filter that must be installed. 4. Leakage of fluid is a critical issue, so, suitable prevention method & Seals must be adopted. 5. If the hyd. fluid is not disposed properly, it'll be harmful to the environment. ## Vehicle power steering * This system uses hydraulic oil, the pump supplies the oil through control valve to the power cylinder - this can turn the wheels with less effort. ## Hydraulic Jack "litter" * Pumping piston is a small piston that transmits pressure oil to a large piston "power piston" through a check valve - then the weight is lifted. ## Aircraft Hydraulic system "Landing gears & flaps" * The hyd. pump that's coupled to the engines provides hyd. power. * This power is distributed th to other systems by transmission line. * Hydraulic power is converted to mechanical power by actuating cylinder or hydraulic motor. ## Hydraulic Components 1. Reservoir - Required by most aircraft systems to provide a ready source of fluid to hyd. pump, & to contain avarying volume of fluid, the size of reservoir is optimized, so the only amount of fluid needed is carried. 2. Filter - Hyd. Auid cleanliness is essential to proper system function. Filter is needed to remove any contaminants from the fluid. 3. Shut off valve - It's installed at the engine firewall, In the event of engine fire, shut off valve is closed to prevent possible ignition of the hyd. fluid. 4. Control valve - Used in hyd. motors & actuators, it's positioned in & response to amanual or automated system selection. * Such as: moving the flap lever, it can allow pressurized hyd. fluid to flow into the motor or actuator in the appropriate direction. 5. Pressure Relief Valve - In systems of fixed displacement pump, Relief Valves are used to ensure that nominal system pressure is not exceeded, if system pressure is too high, the value is open & fluid is returned to the reservoir. 6. Hydraulic Fuses - Are Inline Safety devices, designed to seal off a hydraulic line - automatically. If pressure becomes too low. 7. Accumulator - Pressure Storage reservoir in which hyd. fluid is held under pressme by an external source of energy, this accumulator enables a hyd. system to cope with extremes of demand using less powerful pump & quick response. * It can work as shock absorber by smoothing out pulsations, in the event of hyd. pump failure the stored energy in accumulator can provide a limited number of brack applications after landing. 8. Power output device - In which the hyd. power is converted to mech power, It can be * a cylinder - to produce linear motion. * a motor - to produce rotary motion. 9. Liquid - medium used to transmit power which is oil, stored in tank or reservoir. 10. Conductors - are pipes or hoses used to transmit oil between hyd. components. ## Hydraulic motors * Convert hyd. energy from pressure into rotany motion & torque to drive an implement or system. * Such as: Fixed positive displacement gear/piston, Variable positive displacemet gear piston. * Applications: Wheel motors, fan drivers, Industrial Machinery. ## Hydraulic cylinders * Convert hyd. energy from pressure into Linear motion & force to actuate, move or lift the system. * Such as: Dual acting - Single acting, multi-stage telescoping, mobile applications, head & Cap applications. * Applications: Construction equipment, Mining, Industry, Agriculture. ## "Schematic of Hydraulic System"  * Filter * Hyd. pump * Fluid Tank * Pressure Regulator * Control Valve * Lift/weight * Piston * Cylinder