AGK Systems - Hydraulic System Principles Flashcards
Is Hydraulic Fluid Compressible?
No its a non compressible fluid (Pascals Law)
What happens when you pressurise a hydraulic fluid system?
Al surfaces in the system will all be subjected to the same pressure, regardless of direction of force
Force Area Pressure Relationship
F = Pressure x Area
Area = Force / Pressure
Pressure = force / Area
Output piston stroke formula
Two types of hydraulic systems?
Passive and Active Systems
Passive System
For brakes on a light a/c
Human power effort
Active System
Used if more power is needed
Use a driven hydraulic pump
What is the psi for a low pressure hydraulic system?
2000psi
What is the psi for a high pressure hydraulic system?
3000 to 4000psi
Hydraulic Fluid properties
Low Viscosity
Resistance to foaming
Lubricator and corrosion resistant
Resistant to heat
Chemically stable
Low Freezing Point (-70°C)
High Boiling Point (80°C)
Non Flammable (Flash point above 100°)
Good storage properties
Two types of fluid
Mineral and Synthetic
Mineral fluid characteristics
E.g. DTD 585
Coloured red
Suitable for high pressure systems
Synthetic rubber seals and hoses only
Synthetic fluid
E.g. Skydrol
3 grades in use 500 500A 700 (Note:500A is purple)
Fire resistant, does not support combustion
Used in systems with butyl rubber/Teflon seals
Hydraulic System advantages
Good way to provide large amounts of powe to remote services
Very little energy lose in transmission of there power
Leaks are relatively easy to spot (mist, looks like smoke)
Lighter than equivalent mechanical system
Provide power advantages for operation of heavy services
Hydraulic System disadvantages
Fluid is highly corrosive
Forces generated can require strong structures
Large systems will still be quite heavy
Susceptible to fluid contamination & damage to hydraulic lines
Hydraulic fluid is a health risk & environmental hazard
