Hydraulic Systems Flashcards
(53 cards)
Hydrostatic Pressure
Pressure generated purely and simply by the height of the fluid.
The pressure exerted is dependant only on the height of fluid.
Pascal’s Law
Pressure will increase equally throughout, at 90° to the sides of the container, irrespective of area, diameter or shape.
What is the effect of the hydraulic force by increasing the surface area?
A larger force will be felt
Relationship between force, pressure and area
Force is equal to pressure x area
FAP Triangle
Passive hydraulic system
No pump
Pressure is only applied when this force applied to a piston
What is the role of a hydraulic pump?
The pump’s purpose is to deliver a flow of fluid to obtain a correct pressure
What are symptoms of air in a passive hydraulic system?
Spongy
If air in the passive hydraulic system is detected what is the correct action to take?
Air must be bled normally
What is the normal hydraulic operating region?
3000psi
Advantage of a high-pressure hydraulic system?
Saves weight, eliminating the need for actuators
Chevron seals in a hydraulic system
Effective in one direction, ideal for high-pressure usage.
The viscosity of a hydraulic fluid should be:
Low to minimise power consumption and resistance to flow.
Filtration in a modern hydraulic system is usually ensured by filters where?
Filters in both the pressure and return lines.
A separate pressure regulator is used in a hydraulic system:
In conjunction with a constant delivery type pump.
What type of piston pumps are used in a hydraulic system?
Axial piston pumps - powerful, but can be off loaded to reduce power consumption.
Formula for Hydraulic Pressure
F = A x P
A = F ÷ P therefore.
Synthetic hydraulic fluid
Skydrol
Phosphate ester-based synthetic oil, irritable to skin and eyes.
Fire resistant less prone to cavitation and has a high boiling point.
What colour identifies synthetic hydraulic fluid
Green or purple
What colour identifies mineral oil
Red
What is the purpose of backing rings in a basic hydraulic system
Prevents extrustion
If the incorrect fluid was used in a hydraulic system;
Damage to the seals could result
Basic System layout of the hydraulic system
Reservoir, pump, actuator/jack and selector valve
Actuator/Jack
Convert pressure energy into linear motion.
Provides the output.
Consist of piston, seals and ram.
Present on undercarriages and flap system.
Selector valve
Allows the supply and return either side of service
For example, extension and retraction of undercarriage.
Extension- small force.
Retraction- lots of force
