Study Hydraulics-Intro+hoses, tubing, fluids, packing Flash Cards

 
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Hydraulics-Intro+hoses, tubing, fluids, packing

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What flushing and cleaning compounds are used on MIL-H-7644?
MIL-H-7644 = Vegatable based fluid:
Flushing: Stoddard or same and new clean fluid.
Cleaning: Stoddard.
What is Neoprene and what fluids are compatible with it?
It is a synthetic flexible, acetyline base, hose material Less resistant to petroleum products than Buna-N. But better abrasion resistance. Do not use with phosphate ester based Skyrol - hydraulic fluid use with MIL-H-5606, petroleum based fluid.
Rankin temperature equals ?
F + 460
Absolute pressure equal
PSIG +14.7
What is the general gas law?
PV/T (sub1) = PV/T (sub 2)
OR
P1V1T2 = P2V2T1
Pressure and temperature are absolute.
What is the Volume formula?
Volume = area x length
VAL
What is the FORCE formula?
Force = area x pressure
FAP
What is the weight of a cubic foot of water? a cubic inch of water?
62.4 lbs for a cubic foot, 0.03611 lbs for a cubic inch.
When does the maximum density of water occur?
At 4 C.
Is density affected by temperature?
YES. An increase in altitude will decrease air density.
Specific Gravity = formula
weight of substance/weight of same volume of water. AND
density of substance/density of water
What is specific gravity? Of water?
SG is the ration of densities, density of a substance compared to water. Water is 1.0
What are a gases properties?
no definite shape,
assumes shape of container
fills container completely
readily transmits pressure
compressible
Lighter than equal volumes of liquid
What are a fluids properties?
not compressible
easily transmits pressure
assume shape of vessel
defined shape
What are 6 advantages of hydraulic systems?
Efficient
lightweight
ease of installation
rapid start/stop
simple to inspect
minimum maintenance
What is an important service reminder for hydraulics?
All systems OFF unless called for by A/C maintenance Manual.
What are a turbine engines safety zones in feet? Front, back?
Front = 25 feet
Back = 100 feet @ idle
250 - 350 @ take off power.
How is a pneumatic line marked?
Color code: Red/Blue
verbage: Pneumatic
Graphics: diamond, black on white
How is a line marked that contains Hydraulic fluid?
Color code: Blue/Yellow,
verbage: Hydraulic
Graphics: circle black on white
Is AL alloy a popular tubing?
Yes. It is easily worked, resistant to corrosion and lightweight.
How are flexible hoses constructed?
A seamless synthetic rubber inner tube covered with layers of steel braid, and an outer layer of rubber impregnated cotton braid.
How is CRES tubing identified?
Each includes manufacturer name, trademark, SAE number, and physical condition of metal.
Why are hydraulic fluids colored? Provide examples:
To aid in identification.
Blue: MIL-H-7644
Red: MIL-H-5606
Purple: Skydrol 500 B-4, LD-4
Red: MIL-H83282 replaces Skydrol
Amber: MIL-H-4170 Type 1
What are the flexible hose pressure classifications?
Low pressure - below 250psi.
Medium pressure - small hoses 1 wire braid, up to 3000psi. Larger hoses to 1500psi.
High pressure - all sizes up to 3000psi.
Other than diameter and material what else is important to know about tubing?
Tubing is also manufactured in various wall thicknesses. Know these as well.
How are lines marked containing fuel? toxic materials and physically dangerous materials such as O2.
1) FLAM
2) TOXIC
3) PHDAN
What is the compatible seal material with a vegetable based fluid?
Natural Rubber
What additive is included with MIL-H-5606? Any hazards?
Petroleum based 5606 includes TCP, tricresyl phosphate - anti wear. This can be absorbed through the skin and cause paralysis if taken internally.
Is MIL-H-5606 flammable?
YES under normal conditions.
What are the seals used with MIL-H-5606?
Buna-N (Nitrile) and Neoprene.
What is the Flushing and cleaning agents of MIL-H-5606?
Flushing: Naptha or Varsol, same and new clean fluid.
Cleaning: Stoddard
What fluid is petroleum mineral based? What color is it dyed?
MIL-H-5606 - RED in color. It is petroleum based with additives.
Is MIL-H-7644 flammable?
YES, highly. MIL-H-7644 is a vegetable based fluid very flammable.
What color is MIL-H-7644?
This is a vegetable based fluid dyed blue. Mostly obsolete.
What are the bases for Hydraulic fluids (4).
Vegetable
petroleum - mineral
Synthetic - Hydrocarbon and Phosphate Ester
What is the most important point to remember when servicing a A/Cs hydraulic systems?
Always check with the airframe manufacturers maintenance manual for details on fluids, maintenance info, etc.
What is viscosity?
A fluids internal resistance to fluid flow.
Free flowing fluids have low viscosity.Excessively low viscosity will allow seal leaks.
What are desirable qualities for hydraulic fluid?
High fire point
High flash point
low heat of combustion
chemical stability
Minimum viscosity change with Temp.
Lubricity
Wide temperature range
Acceptable expansion and contraction with temp.
What O ring materials are adopted for use with MIL-H-5606 (Petroleum based) system?
MS28775 series, good from -65F to 275F. Compatible material is Buna-N, Nitryl and Neoprene.
Where are wipers used? Name the materials?
Wipers clean and lube exposed parts of piston shafts. Metallic and felt materials.
Name some gasket materials and their use.
Asbestos- exhaust systems
copper - spark plugs
cork - oil seals, gap filler
rubber sheeting - compressible gasket, no oil or fuel contact.
What is a U Ring and where are they used?
Seals pressure in one direction, used in brake assemblies and master cylinders. Typically low pressure, < 1000psi.
What is a V Ring and why are they special?
One way seals, opening faces pressure. Requires male/female retainer to hold them in proper position.
How are back up rings used, marked and inspected?
They are typically Teflon, they are not color coded, but the bag is marked, inspection of scarf joint and surfaces is needed. Ring should not open more than 1/4 inch.
How do you inspect an O Ring?
With a 4 power magnifying glass, looking for nicks, cuts, scraps or cracks, irregularities, foreign particles.
How are Packings marked?
Color code or label in their container. Coding has no means to establish age.
What is the purpose of the O-ring? Good to what pressures?
Prevent pressure in both directions. Good to 1500psi and above with a backing ring. Backing ring is placed on the side of the O-ring away from the pressure.
What are packings, where are they used? What are some typical forms.
Packings are used in systems with moving parts, pumps, selector valves, actuators, etc. Come in the form O-ring, V-ring, U-ring.
What are the three main catagories of seals?
Packing, gaskets, wipers.
What are 4 criteria for a seal selection?
1) Pressure
2) fluid
3) metal finish and clearance of parts
4) Type of motion - rotary or reciprocating
Why are seals used?
Seals prevent fluid from passing a certain point and keep dirt and air out of a system.
How are fluid lines identified in AC?
Color codes, words and geometric. Symbols relate to the material in the tube and use? AC65-9A Page. 102.
How is flexible hoses sized?
in 1/16ths inch increments of inside diameter, similar to semi-rigid tubing and identical to the similar rigid tubing.
What are the advantages of Teflon hoses? Describe the construction of flexible Teflon hose.
They can handle most anything, including most fluids and pressures found in AC. Teflon tube is braided over with SST mesh for strength and protection.
How are flexible hoses marked?
They use lines, letters, numbers. Hoses compatible with phosphate ester Skydrol are so marked.
What is Teflon and what fluids are compatible with it?
Teflon is a DuPont trade name for tetrafluoroethylene resin. Compatible with nearly every substance or agent.
What is Butyl and what fluids are compatible with it?
It is a synthetic rubber flexible hose material made from petroleum raw materials. Do not use with petroleum products. Ok to use with phosphate ester based Skyrol - hydraulic fluid.
What is Buna -N and what fluids are compatible with it?
It is a synthetic flexible hose material compatible with petroleum products. Do not use with Skyrol - hydraulic fluid.
Name 4 materials that flexible hose are constructed of.
Buna - N, Neoprene, Butyl, Teflon.
How is tubing sized?
By the outside diameter dimension in 16ths. A number 6 tubing is 3/8", #8 is 1/2 inch.
Where is CRES tubing used?
Landing gear, flaps, brakes - high pressure hydraulic applications. External brakes lines should always be CRES.
How is AL tubing marked for identification?
Stamped on the surface (large tubing) or color coded on smaller diameter tubes.
How can you determine between tubing materials: annealed austenitic and ferritic stainless steels.
Magnet test. Austenitic are nonmagnetic and straight chromium carbon and low alloy steels are very magnetic.
What is an advantage of CRES tubing over AL.
It higher tensile strength means thinner wall thicknesses can be used so over all weight is slightly more than thicker wall AL tubing.
What other tubing material is used?
CRES with 3000 psi or greater, also in wheel wells or areas that see a lot of abuse.
Is copper a good tubing material?
NO. It is being replaced by AL or CRES, SST. CU has a high fatique factor and hardens and becomes brittle from vibration and cracks.
How is tubing sized when being replaced in a pressurized system?
The same size tubing is installed, unless AD or some other directive calls for different.
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