Hydraulics Flashcards
What are the main topics in the hydraulic outline?
How hydraulics work, Accumulator, Pumps, Fluid, Undercarriage, System faults, Brakes, Brake failures.
Why is hydraulics used in aircraft systems?
Hydraulics is a very efficient way to operate many aircraft systems.
Where can the heart of the hydraulic system be located?
The heart of the hydraulic system can be located anywhere in the aircraft.
How can hydraulic systems be operated?
Hydraulic systems can be manual, as in brakes, or electrically driven, as in some undercarriage systems.
What is a standpipe in hydraulic systems?
A standpipe ensures that the system doesn’t use fluid from the bottom of the reservoir, reserving fluid for emergency use when the normal system fluid level is low.
What components help regulate pressure in hydraulic systems?
Pressure regulators for normal operation and pressure relief valves in case of overpressure.
What happens when hydraulic fluid is low?
The system can function normally but with less fluid moving during emergencies; pressure remains the same.
What prevents fluid surging in hydraulic systems?
Baffles are located in the system to prevent surging and sloshing.
What are the main components of a basic hydraulic system?
Reservoir, System Relief Valve, Pump, Check Valves (C.V.), Selector Valve, Double-Acting Cylinder, Hydraulic Pressure, Hydraulic Fluid Supply, Return Fluid.
What does the double-acting cylinder in a hydraulic system do?
It converts hydraulic pressure into motion.
What happens to the ram in the hydraulic system when pressure is applied to the actuator?
The ram is forced out.
What happens to the ram in the hydraulic system when the actuator pressure is reversed?
The ram is forced in.
What does a more complex hydraulic system include?
More units like a power pump, filter, pressure regulator, accumulator, selector valves (SV), and system relief valves.
What are the two chambers in a hydraulic accumulator filled with?
One chamber is filled with nitrogen and the other with hydraulic fluid.
Why are accumulators mainly fitted to larger aircraft?
They require a lot of pressure for braking, extending, and retracting gear or flight controls like flaps.
What is the purpose of an accumulator in a hydraulic system?
It maintains line pressure during pump failure or when the pump cannot keep up. It also dampens pulsations and allows for thermal expansion.
What are the two types of hydraulic accumulators?
Piston accumulator and bladder accumulator.
What does a piston accumulator consist of?
It has a cylinder, piston, gas section, and hydraulic fluid section.
What does a bladder accumulator consist of?
It has a bag, gas section, hydraulic fluid section, and anti-extrusion valve.
What is the main function of a gear pump in a hydraulic system?
To convert low-pressure fluid from the inlet into high-pressure fluid at the outlet.
What are the key components of a gear pump?
Driver gear, driven gear (or idle gear), driver shaft, casing, and inlet/outlet ports.
What is a variable displacement valve?
A valve that adjusts fluid flow by altering the position of the swashplate and pistons.
What are the main parts of a variable displacement valve?
Swashplate, pistons, cylinder block, drive shaft, inlet valve plate slot, and outlet valve plate slot.
What is the purpose of a check valve in a hydraulic system?
To allow fluid to flow in one direction only, preventing backflow.
What can cause a check valve to malfunction?
Foreign debris can cause the valve to stick open or closed.
What are the essential roles of hydraulic fluids?
Lubricate, cool, and clean the system.
What are the three types of hydraulic fluids?
Vegetable-based, mineral-based, and synthetic-based.
What characteristics must hydraulic fluids have?
Low viscosity, low freezing point, high boiling point, non-corrosive, non-flammable, and usually colored red.
What types of systems can operate retractable aircraft landing gear?
Electrics, hydraulics, or pneumatics.
What features are typically included in retractable landing gear systems?
Uplocks/downlocks, anti-retraction devices, emergency systems, and free-fall deployment.
What are the three common system faults in hydraulic systems?
Air in the system, leaks in the system, and low accumulator pressure.
What problems can air in the hydraulic system cause?
Overheating and restricted ram movement due to compressibility of air.
What is the primary function of disc brakes in hydraulic systems?
They use fluid pressure from the brake pedal to make the cylinders clamp on the disc, stopping the rotation.
What components are involved in the disc brake system?
Brake pedal, master cylinder, caliper brake, brake pads, disc rotor, and vacuum power brake booster.
What are the main topics in the hydraulic outline?
How hydraulics work, Accumulator, Pumps, Fluid, Undercarriage, System faults, Brakes, Brake failures.
Why is hydraulics used in aircraft systems?
Hydraulics is a very efficient way to operate many aircraft systems.
Where can the heart of the hydraulic system be located?
The heart of the hydraulic system can be located anywhere in the aircraft.
How can hydraulic systems be operated?
Hydraulic systems can be manual, as in brakes, or electrically driven, as in some undercarriage systems.
What is a standpipe in hydraulic systems?
A standpipe ensures that the system doesn’t use fluid from the bottom of the reservoir, reserving fluid for emergency use when the normal system fluid level is low.
What components help regulate pressure in hydraulic systems?
Pressure regulators for normal operation and pressure relief valves in case of overpressure.
What happens when hydraulic fluid is low?
The system can function normally but with less fluid moving during emergencies; pressure remains the same.
What prevents fluid surging in hydraulic systems?
Baffles are located in the system to prevent surging and sloshing.
What are the main components of a basic hydraulic system?
Reservoir, System Relief Valve, Pump, Check Valves (C.V.), Selector Valve, Double-Acting Cylinder, Hydraulic Pressure, Hydraulic Fluid Supply, Return Fluid.
What does the double-acting cylinder in a hydraulic system do?
It converts hydraulic pressure into motion.
What happens to the ram in the hydraulic system when pressure is applied to the actuator?
The ram is forced out.
What happens to the ram in the hydraulic system when the actuator pressure is reversed?
The ram is forced in.
What does a more complex hydraulic system include?
More units like a power pump, filter, pressure regulator, accumulator, selector valves (SV), and system relief valves.
What are the two chambers in a hydraulic accumulator filled with?
One chamber is filled with nitrogen and the other with hydraulic fluid.
Why are accumulators mainly fitted to larger aircraft?
They require a lot of pressure for braking, extending, and retracting gear or flight controls like flaps.
What is the purpose of an accumulator in a hydraulic system?
It maintains line pressure during pump failure or when the pump cannot keep up. It also dampens pulsations and allows for thermal expansion.
