Navedtra 14105 Fluid Power Chapter 5-7

Front 1

True or False. The threads of newly threaded pipe do not corrode if the fittings cover all of the exposed threading.

Back 1

False

Front 2

True or False. Pipe compounds prevent corrosion and assist in the disassembly of threaded joints.

Back 2

True

Front 3

True or False. Excess pipe compound that may ooze inside lines does not present problems if the compound is compatible with the fluid in the system.

Back 3

False

Front 4

True or False. The use of threaded connectors is generally limited to low-pressure systems.

Back 4

True

Front 5

This connector is attached to the piping by welding, brazing, tapered thread, or rolling and bending.

Back 5

Flange

Front 6

This connector connects subassemblies in some fluid power systems, especially in high-pressure systems that use pipe for the fluid lines

Back 6

Welded

Front 7

This connector is commonly used for joining nonferrous piping in the pressure and temperature range where its use is practical

Back 7

Brazed

Front 8

True or False. The fitting of a flared connector should be made of material having greater strength than that of its sleeve and nut and of the piping.

Back 8

False

Front 9

A universal fitting is one that can be?

Back 9

positioned to the angle required for the installation

Front 10

This connector is tightened 1/6 turn past the specified torque.

Back 10

steel flared type

Front 11

This connector may not be tightened past the specified torque.

Back 11

Aluminum alloy flared type.

Front 12

This connector must be turned with a wrench 1/6 turn past handtight

Back 12

flareless type

Front 13

True or False. Quick-disconnect couplings are provided with an automatic shutoff feature which prevents loss of fluid from the system or entrance of foreign matter into the system when they are disconnected.

Back 13

True

Front 14

Manifolds are ued in the pressure supply and/or return lines of fluid power systems to perform what functions?

Back 14

conserve space, reduce joints, and eliminate piping

Front 15

In long pieces of tubing or pieces bent to a complex shape, rust and scale can be removed by what process?

Back 15

pickling

Front 16

Valves are used to control what in fluid power systems?

Back 16

direction of fluid flow, fluid pressure, and fluid flow

Front 17

Its flow is controlled by raising or lowering discs or wedges.

Back 17

globe

Front 18

Flow or no-flow through it is controlled by turning the valve shaft one-quarter turn.

Back 18

ball

Front 19

Certain types are used as variable restrictors

Back 19

needle

Front 20

True or False. Gate valves are suitable for use as throttling valves because they close in small increments.

Back 20

False

Front 21

True or False. The globe valve gets its name from the globular shape of its body, a shape that is unique to this valve.

Back 21

False

Front 22

Approximately how far must the handwheel of a globe valve be turned toward the closed position after the valve has been fully opened?

Back 22

1/2 turn

Front 23

What type of flow control valve makes the most suitable throttle valve?

Back 23

Needle

Front 24

Relief valves are used for what functions?

Back 24

to prevent pressure from rising above a predetermined level

Front 25

True or False. If a fluid power system uses two or more relief valves, they must all be the same size.

Back 25

False

Front 26

Chatter in a relief valve is the result of?

Back 26

rapid opening and closing of the valve as it hunts above and below a set pressure

Front 27

When the system pressure increases above the pressure to which the valve is set, the main valve opens?

Back 27

only after the system pressure increases to more than can be relieved by the pilot valve

Front 28

After the main valve has relieved the system and when pressure returns to normal, what does the pilot valve do?

Back 28

It closes first and allows pressure to equalize above and below the main piston

Front 29

A hydraulic pressure regulator does what?

Back 29

maintains the system pressure between two predetermined levels

Front 30

Chatter of a pressure regulator may be prevented by?

Back 30

maintaining a very small differential pressure.

Front 31

What is the operational state of the regulator when the system pressure is less than that required to operate one of the activating units in the system?

Back 31

the check valve is unseated, the pilot valve is unseated, and fluid is flowing into the system and into the return line

Front 32

True or False. For the pressure-controlled sequence valve to operate properly, the tension of the spring must be sufficient to hold the piston in the closed position against pressure required to operate the primary unit.

Back 32

True

Front 33

A poppet is used as the valving element for what fluid power valve applications?

Back 33

flow control, pressure control, and directional control

Front 34

What type of valving element is most ocmmonly used in directional control applications?

Back 34

sliding spool

Front 35

Check valves usually contain what types of valving elements?

Back 35

ball and cone

Front 36

What type of check valve permits free flow of fluid in one direction and a limited flow of fluid in the opposite direction.

Back 36

orifice

Front 37

True or False. When the pilot chamber of the three-way, poppet-type, normally closed directional control valve is pressurized, fluid flows from the actuating cylinder through the valve and out the exhaust port.

Back 37

False

Front 38

Which four-way valves are actuated by cams?

Back 38

poppet

Front 39

What type of valve is considered most trouble free of all four-way valves?

Back 39

sliding spool

Front 40

Suitable packing devices for fluid power systems are made from materials that possess what characteristics?

Back 40

Compatibility with fluids used in the systems, effective sealing ability, and durability

Front 41

True or False. No internal leakage should be allowed to occurwithin a hydraulic power system because of the resulting loss in system efficiency.

Back 41

False

Front 42

What factors are used in determining the material used as a sealing device for a particular application?

Back 42

type of motion

Front 43

Cork is suitable for use as gaskets because of what characteristics?

Back 43

its compressibility

Front 44

You are reassembling a vital component which uses a copper sealing ring and discover there is not a new replacement ring. What step should you take?

Back 44

reinstall the old ring after it has been annealed

Front 45

Although it has many of the characteristics required in an effective seal, what materials are not used as packing material in a system in which petroleum-base fluid is used?

Back 45

natural rubber

Front 46

True or False. T-seals provide a positive seal at low pressure and there is no military standard part numbering system to identify T-seals.

Back 46

True

Front 47

True or False. The dash (-) numbers used to identify the size of T-seals are part of a preliminary numbering system.

Back 47

False

Front 48

True or False. To obtain the correct squeeze or clearance on V-ring packing, shmis or spacers are used to adjust the packing gland depth.

Back 48

True

Front 49

True or False. Regardless of its condition, an O-ring must be discarded if it cannot be positively identified.

Back 49

True

Front 50

What items can be used to identify replacement O-rings?

Back 50

allowance parts lists (APLs), technical manuals, and system drawings

Front 51

What is the basis for computing the age of an O-ring?

Back 51

the cure date

Front 52

What is the expiration date of an O-ring which was cured on 13 July 1990 and has a 4 year shelf life?

Back 52

13 July 1994

Front 53

What materials should NOT be used to fabricate tools for use in removing and installing O-ring and backup rings?

Back 53

steel

Front 54

Why are O-rings sometimes rolled on a cone or dowel?

Back 54

to expose and stretch the inner diameter surface for inspection

Front 55

What is the first step in replacing an O-ring in a disassembled fluid power system component?

Back 55

identify the ring's size and material

Front 56

What is used when the O-ring installation requires spanning or inserting through sharp threaded areas, ridges, slots, and edges?

Back 56

O-ring entering sleeves

Front 57

What device is used to prevent O-ring seal extrusion under pressure?

Back 57

backup ring

Front 58

Backup rings made from what materials are the most widely used?

Back 58

tetrafluorethylene (TFL)

Front 59

What is the age of deterioration of TFE backup rings?

Back 59

TFE does not deteriorate

Front 60

When the packing in a fluid power system component is being replaced, the backup washers should be inspected for what conditions?

Back 60

fray, cuts, and evidence of compression damage

Front 61

True or False. A quad ring can be used at extremely high pressures.

Back 61

True

Front 62

True or False. A quad-ring provides a seal in only one direction.

Back 62

False

Front 63

True or False. A quad-ring eliminates the spiral twist sometime encountered with O-rings.

Back 63

True

Front 64

True or False. A quad-ring can be used as a static seal as well as a packing for reciprocationg or rotary motion.

Back 64

True

Front 65

True or False U-cups and U-packings are usually made of different materials and they both seal on the OD and the ID.

Back 65

True

Front 66

True or False. U-rings and u-packings are interchangeable.

Back 66

False

Front 67

What type of seal is least desirable and is used ony where there is not sufficient space for a U-ring packing or a V-ring packing?

Back 67

flange

Front 68

How are O-rings stored?

Back 68

they are kept in their original envelope

Front 69

A torn O-ring package is properly secured with what materials?

Back 69

pressure-sensitive, moitureproof tape.