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What is the primary purpose of practical hydraulic systems in modern aircraft?
What is the primary purpose of practical hydraulic systems in modern aircraft?
What type of pumps are used in modern aircraft to move an incompressible fluid under pressure?
What type of pumps are used in modern aircraft to move an incompressible fluid under pressure?
What is the advantage of hydraulic systems over electric or pneumatic systems in modern aircraft?
What is the advantage of hydraulic systems over electric or pneumatic systems in modern aircraft?
What is the fundamental principle underlying hydraulic systems, as described by Blaise Pascal?
What is the fundamental principle underlying hydraulic systems, as described by Blaise Pascal?
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What is the unit of measurement for force in practical fluid power?
What is the unit of measurement for force in practical fluid power?
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What is the definition of pressure in the context of hydraulic systems?
What is the definition of pressure in the context of hydraulic systems?
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What is the unit of measurement for pressure in hydraulic systems?
What is the unit of measurement for pressure in hydraulic systems?
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What is the term for the cause of motion or change in the context of hydraulic systems?
What is the term for the cause of motion or change in the context of hydraulic systems?
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What is a key characteristic of the fluid used in hydraulic systems?
What is a key characteristic of the fluid used in hydraulic systems?
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What is the purpose of an electrical system interface in a hydraulic system?
What is the purpose of an electrical system interface in a hydraulic system?
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What is the main advantage of using hydraulic systems in aircraft?
What is the main advantage of using hydraulic systems in aircraft?
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What is the role of hydraulic systems in aircraft landing gear?
What is the role of hydraulic systems in aircraft landing gear?
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What is the relationship between hydraulic systems and fluid power systems?
What is the relationship between hydraulic systems and fluid power systems?
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What is the mechanical advantage of a hydraulic system achieved by?
What is the mechanical advantage of a hydraulic system achieved by?
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What is the unit of measurement for the flow rate in a hydraulic system?
What is the unit of measurement for the flow rate in a hydraulic system?
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What is the relationship between horsepower and gallons per minute, pounds per square inch, and a constant value in a hydraulic system?
What is the relationship between horsepower and gallons per minute, pounds per square inch, and a constant value in a hydraulic system?
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What is the advantage of a hydraulic system over other mechanical systems?
What is the advantage of a hydraulic system over other mechanical systems?
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What is the pressure produced by a piston of one square inch pressing down with a force of one pound?
What is the pressure produced by a piston of one square inch pressing down with a force of one pound?
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How much force will be produced by a piston with an area of 20 square inches if it is connected to a cylinder with a piston of one square inch pressing down with a force of one pound?
How much force will be produced by a piston with an area of 20 square inches if it is connected to a cylinder with a piston of one square inch pressing down with a force of one pound?
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What is the volume of fluid displaced by a piston of one square inch pressing down with a force of one pound for every inch it moves?
What is the volume of fluid displaced by a piston of one square inch pressing down with a force of one pound for every inch it moves?
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What is the relationship between the output force and the input force in a hydraulic system?
What is the relationship between the output force and the input force in a hydraulic system?
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What is the primary function of the selector valve in a hydraulic system?
What is the primary function of the selector valve in a hydraulic system?
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What is the purpose of the reservoir in a hydraulic system?
What is the purpose of the reservoir in a hydraulic system?
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What is the function of the accumulator in a hydraulic system?
What is the function of the accumulator in a hydraulic system?
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What is the function of the heat exchanger in a hydraulic system?
What is the function of the heat exchanger in a hydraulic system?
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What is the primary purpose of the pumps in a hydraulic system?
What is the primary purpose of the pumps in a hydraulic system?
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What happens to the hydraulic fluid after it leaves the actuating cylinder?
What happens to the hydraulic fluid after it leaves the actuating cylinder?
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What is the role of hydraulic system components in aircraft?
What is the role of hydraulic system components in aircraft?
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What is the relationship between hydraulic systems and fluid power systems?
What is the relationship between hydraulic systems and fluid power systems?
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What is the purpose of the electrical system interface in a hydraulic system?
What is the purpose of the electrical system interface in a hydraulic system?
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What is the characteristic of hydraulic systems that makes them suitable for use in aircraft?
What is the characteristic of hydraulic systems that makes them suitable for use in aircraft?
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What is the primary function of an accumulator in a hydraulic system?
What is the primary function of an accumulator in a hydraulic system?
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What is the purpose of a heat exchanger in a hydraulic system?
What is the purpose of a heat exchanger in a hydraulic system?
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What is the primary function of a valve in a hydraulic system?
What is the primary function of a valve in a hydraulic system?
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What is the primary function of a filter in a hydraulic system?
What is the primary function of a filter in a hydraulic system?
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What is the primary function of an actuator in a hydraulic system?
What is the primary function of an actuator in a hydraulic system?
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What is the product of force and distance?
What is the product of force and distance?
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What is the unit of force in the MKS system of units?
What is the unit of force in the MKS system of units?
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What is power in terms of force, distance, and time?
What is power in terms of force, distance, and time?
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If 1 newton-metre equals 1 joule, what is 1 joule equal to in foot-pounds?
If 1 newton-metre equals 1 joule, what is 1 joule equal to in foot-pounds?
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What is the unit of distance in most power computations?
What is the unit of distance in most power computations?
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What is the formula for calculating work?
What is the formula for calculating work?
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What is the formula to calculate power in a hydraulic system?
What is the formula to calculate power in a hydraulic system?
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What is the mechanical advantage achieved in a hydraulic system?
What is the mechanical advantage achieved in a hydraulic system?
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What is the resulting force produced by a piston with an area of 20 square inches connected to a cylinder with a piston of one square inch pressing down with a force of one pound?
What is the resulting force produced by a piston with an area of 20 square inches connected to a cylinder with a piston of one square inch pressing down with a force of one pound?
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How much horsepower is produced by one gallon per minute of flow under a pressure of one pound per square inch?
How much horsepower is produced by one gallon per minute of flow under a pressure of one pound per square inch?
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What is the volume of fluid displaced by a piston of one square inch pressing down with a force of one pound for every inch it moves?
What is the volume of fluid displaced by a piston of one square inch pressing down with a force of one pound for every inch it moves?
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What is the advantage of hydraulic systems over other mechanical systems?
What is the advantage of hydraulic systems over other mechanical systems?
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What is the unit of measurement for flow rate in a hydraulic system?
What is the unit of measurement for flow rate in a hydraulic system?
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What is the primary function of a ball check valve?
What is the primary function of a ball check valve?
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What type of valve is used to relieve excessive pressures that may exist due to thermal expansion of the fluid?
What type of valve is used to relieve excessive pressures that may exist due to thermal expansion of the fluid?
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What is the purpose of a system relief valve?
What is the purpose of a system relief valve?
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What happens when pressurized fluid in the line builds to an excessive amount in a thermal relief valve?
What happens when pressurized fluid in the line builds to an excessive amount in a thermal relief valve?
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What type of valve is illustrated in this Figure?
What type of valve is illustrated in this Figure?
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What is the purpose of a relief valve in a hydraulic system?
What is the purpose of a relief valve in a hydraulic system?
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Why are pressure relief valves used in hydraulic systems?
Why are pressure relief valves used in hydraulic systems?
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What is the main characteristic of a double-acting balanced actuator?
What is the main characteristic of a double-acting balanced actuator?
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What is the function of the teeth on the piston shaft in a rotary actuator?
What is the function of the teeth on the piston shaft in a rotary actuator?
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What is the primary purpose of a heat exchanger in a hydraulic system?
What is the primary purpose of a heat exchanger in a hydraulic system?
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Where are heat exchangers typically located in a hydraulic system?
Where are heat exchangers typically located in a hydraulic system?
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What is an example of an application where a rotary actuator is used?
What is an example of an application where a rotary actuator is used?
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What is a characteristic of the fluid used in a double-acting balanced actuator?
What is a characteristic of the fluid used in a double-acting balanced actuator?
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What is the purpose of the pinion gear in a rotary actuator?
What is the purpose of the pinion gear in a rotary actuator?
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What is a type of heat exchanger used in hydraulic systems?
What is a type of heat exchanger used in hydraulic systems?
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What is the primary function of the No. 1 system in the GENFLY Hydraulic System?
What is the primary function of the No. 1 system in the GENFLY Hydraulic System?
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What is the function of the electro-hydraulic pump (EHP) in the No. 1 system?
What is the function of the electro-hydraulic pump (EHP) in the No. 1 system?
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What is the function of the hand pump circuit in the GENFLY Hydraulic System?
What is the function of the hand pump circuit in the GENFLY Hydraulic System?
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What is the function of the pressure relief valves in the GENFLY Hydraulic System?
What is the function of the pressure relief valves in the GENFLY Hydraulic System?
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What is the function of the filters in the GENFLY Hydraulic System?
What is the function of the filters in the GENFLY Hydraulic System?
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What is the function of the No. 2 system in the GENFLY Hydraulic System?
What is the function of the No. 2 system in the GENFLY Hydraulic System?
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What is the function of the engine driven pumps (EDPs) in the GENFLY Hydraulic System?
What is the function of the engine driven pumps (EDPs) in the GENFLY Hydraulic System?
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What is the purpose of the individual reservoirs in the GENFLY Hydraulic System?
What is the purpose of the individual reservoirs in the GENFLY Hydraulic System?
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Study Notes
Hydraulic Systems
- Open hydraulic systems, like rivers, can produce great amounts of power, but practical systems are used to transmit power from one place to another.
- Engine-driven or electrically driven hydraulic pumps are used in aircraft to move an incompressible fluid under pressure to actuators to perform tasks like raising or lowering landing gear or flaps.
Pascal's Law
- Pascal's Law states that any increase in pressure on a confined liquid is transmitted equally and undiminished to all parts of the container, acting at right angles to the enclosing walls.
- This means that if a force is applied to a piston in an enclosed vessel, the increase in pressure will be the same anywhere in the system.
Force and Pressure
- Force is energy exerted or brought to bear, causing motion or change, expressed in pounds or grams.
- Pressure is force applied over a given area, expressed in pounds per square inch (PSI) or grams per square centimeter (g/cm²).
Hydraulic Systems Components
- Hydraulic systems consist of pumps, actuators, and other components that work together to transmit power.
- Hydraulic systems are used in aircraft for tasks like landing gear and flight control systems.
Mechanical Advantage
- Mechanical advantage is the ratio of output force to input force applied to a mechanism.
- Hydraulic systems have a large gain in mechanical advantage due to varying piston sizes, allowing for the transmission of force over large distances and into and out of sealed compartments.
Power Transmission
- Power in hydraulic systems can be computed by considering the flow rate in gallons per minute and pressure in pounds per square inch.
- One gallon per minute of flow under a pressure of one pound per square inch produces 0.000583 horsepower.
Hydraulic Systems Introduction
- Hydraulic systems use pressurized liquid to generate, control, and transmit power.
- Hydraulic systems are used in aircraft, including landing gear and flight control systems.
- Hydraulic systems are a branch of fluid power systems, which move fluid to do work.
Components of Hydraulic Systems
- Reservoir: stores hydraulic fluid, supplies the operating needs of the system, and replenishes fluid lost through leakage.
- Pumps: engine-driven or hand-driven, boost hydraulic fluid pressure to system requirements.
- Valves: control the flow of fluid, directing it to the actuating cylinder.
- Filter: removes contaminants from the hydraulic fluid.
- Accumulator: stores energy by compressing gas or fluid, releasing it as needed.
- Heat exchanger: cools or heats the hydraulic fluid as needed.
- Actuators: convert hydraulic pressure into mechanical motion.
Hydraulic System Operation
- Hydraulic fluid flows from the reservoir to the pump, then to the selector valve, which directs fluid to the actuating cylinder.
- The actuating cylinder moves in response to the direction of fluid flow.
Pascal's Law
- States that pressure applied to a confined fluid is transmitted equally in all directions.
Mechanical Advantage in Hydraulic Systems
- Hydraulic systems can provide mechanical advantage, increasing force or speed with minimal input force.
Maintenance and Safety
- Regular maintenance is essential to ensure hydraulic system reliability and safety.
- General hydraulic safety precautions include following proper procedures and wearing protective gear.
Units of Pressure and Distance
- Other units of pressure may be encountered, but they can be converted back into basic units of force and area.
- Distance is a key concept in practical mechanics, often expressed in feet (Ft) or metres (M).
Work and Power
- Work is done when a force causes an object to move, calculated by multiplying the force used on the object by the distance it travelled.
- Work is expressed in foot-pounds (lb-ft) or kilogram-metres (kg-m).
- Power is the rate of doing work, calculated by multiplying force by distance and dividing by time (P = F × D ÷ T).
- In hydraulic systems, power can be computed by considering the flow rate in gallons per minute and the pressure in pounds per square inch.
Mechanical Advantage in Hydraulic Systems
- Mechanical advantage is the ratio of output force to input force applied to a mechanism.
- Hydraulic systems have two major advantages: ease of transmitting force over large distances and into sealed compartments, and large gain in mechanical advantage by varying piston sizes.
Relief Valves
- Relief valves are pressure-operated valves that bypass pump delivery pressure to the reservoir.
- System relief valves are used as safety devices against pump failure, while thermal relief valves are used to relieve excessive pressures due to thermal expansion of the fluid.
Actuators
- Double-acting balanced actuators have the same surface area on both sides of the piston and are used where the amount of force required is the same in both directions.
- Rotary actuators use a piston with a rack of teeth that meshes with a pinion gear, and are used in systems such as landing gear and steering systems.
Heat Exchangers
- Heat exchangers are components that transfer heat from one body to another.
- They are used to cool hydraulic fluid in hydraulic systems, often located in the return side of the system.
- Heat exchangers are available in various forms, including air-cooled and fuel-cooled types.
Hydraulic System Layout and Operation
- On the GENFLY Trainer, hydraulic power is used to operate various systems, including ailerons, spoilers, rudder, elevators, flaps, and slats, landing gear, nose wheel steering, and wheel brakes.
- The hydraulic system is divided into two independently pressurized systems, No. 1 and No. 2, with individual reservoirs and engine-driven pumps.
- Pressure relief valves and filters are used to prevent over-pressurization and contamination, respectively.
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Description
Learn about the application of hydraulic systems in modern aircraft, including engine driven or electrically driven hydraulic pumps and their uses.