Hydraulics 2 Flashcards
To control a sequence of operations and to enable one unit to automatically set another unit into motion
purpose of a hydraulic sequence valve
Are installed in one or both actuating cylinder working lines, depending on the type of action required.
Sequence valves
Will go to the first unit
Direct line
Goes to the second unit
Branchline
Two types of sequence valves
Balanced and unbalanced
Has a check valve with equal working areas which cannot be on seated by fluid pressure in either direction unless the plunger is depressed
Balanced sequence valve
Can be understood by fluid pressure below it without having to pull and you’re depressed
Unbalanced sequence valve
Most common cause of hydraulic system malfunction
Leakage of hydraulic fluid
Cannot be visually seen making it difficult to locate
Symptom is sluggish or erratic operation of the unit
Internal leakage
Can be seen is indicated by streaks or puddles of hydraulic fluid.
Symptom is slow movement of the unit with visible fluid loss
external leakage
Fluid from spillage can be the cause of a violent explosion or fire if it comes in contact with pure oxygen
Hazard
Sealing materials
Cork, leather, metal, and rubber
Are used throughout aircraft hydraulic systems to minimize internal and external leakage
Seals
2 classifications of seals
Gaskets and packings
Is a seal used with stationary units; it experiences no relative motion between itself and the surface with which it is in contact
(Static seal)
Gasket
Is a seal used with moving units; it experiences relative motion between itself and the surface with which it is in contact.
(Running or dynamic seal)
Packings
2 types or synthetic rubber seals
Synthetic rubber and fabricated seal
Do not deteriorate with age and tolerate temperatures in extreme of those found in high-pressure hydraulic systems Diagonal cut (scarf cut) to aid in installation
Teflon
Scrapes the piston rod clean as it is retracted into the unit
Metallic wipers
Located behind the metallic wiper and their purpose is to lubricate the retracting piston rod after the ride has been scraped clean by the metallic wiper
Felt wipers
What should not be used to cover danger areas or components.
Adhesive tape
Fluid line identification
Bands of paint or strips of tape and metal tags
Identified by the use of tape approximately 1 inch wide, on which words, colors, and geometric symbols are printed.
Identification of tape codes
Flam
Toxic
Aahm
Phdan
Flammable, toxic and poisonous materials, anesthetic and harmful materials, and physically dangerous materials
Used for high pressure, Most common types of tubing
Corrosion resistant steel tubing
Used in half pressure and general purpose
Aluminum alloy tubing
Used to connect moving parts with stationary parts and in location subject to severe vibrations
Flexible hoses
