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Hydraulics > Chapter 10 > Flashcards

Chapter 10 Flashcards

1
Q

Name the three control factors produced by the various types of valves in a hydraulic circuit.

A

System pressure

Directing flow

Flow rate

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2
Q

Controlling the flow rate of fluid entering an actuator controls the _______ of that actuator.

A

Speed

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3
Q

In hydraulic components, a spool or piston often operates in a precision machined _______ without using seals to prevent leakage between the parts.

A

Bore

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4
Q

List the three sources of external force that can be used to position control valve elements.

A

Manual force

Pilot force

Electromagnetic force

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5
Q

If the outlet line of a control valve is subjected to system operating pressure, it must use a(n) ______ drain.

A

External

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6
Q

Name the three basic uses of springs in the operation of hydraulic control valves.

A
  • Positioning a spool or piston
  • establishing maximum pressure in a valve,
  • serving as a biasing device in pressure or flow control valves.
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7
Q

The pressure at which a pressure control valve just opens is called the ______ pressure of the valve.

A

Cracking

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8
Q

Heavy internal springs are used to establish the operating pressure of the ______ -operated type of pressure control valve.

A

Direct

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9
Q

A compound relief valve commonly makes use of a(n) ______ and a(n) ______ in its operation.

A

Pilot stage

Balancing piston

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10
Q

A(n) ______ drain must be used with sequence valves since both the initial and secondary sides of the valve are subjected to system pressure at the same time during system operation.

A

External

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11
Q

Counterbalance and brake valves provide ______ control in hydraulic systems.

A

Restrained movement

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12
Q

Brake valves are used in some hydraulic motor circuits to prevent ______ loads from turning the motor at a higher-than-desired speed.

A

Overrunning

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13
Q

An unloading relief valve uses a(n) ______ mechanism to assist in the operation of the balancing piston in the pilot section of the valve.

A

Plunger

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14
Q

A(n) ______ valve restricts a portion of a hydraulic circuit to a maximum operating pressure that is below the setting of the system relief valve.

A

Pressure reducing

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15
Q

What are the four general classifications of directional control valves used in a hydraulic system?

A
  • Shut-off valves
  • check valves
  • three-way valves
  • four-way valves.
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16
Q

List the five common types of shut-off valves used in a hydraulic system.

A
  • Globe
  • gate
  • ball
  • spool
  • needle
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17
Q

______ valves are used in hydraulic systems as both shut-off and metering devices.

A

Needle

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18
Q

______ directional control valves are designed for the actuation of rams and single-acting cylinders.

A

Three way

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19
Q

The ______ directional control valve is generally used in systems with double-acting cylinders or hydraulic motors.

A

Four way

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20
Q

Which type of the valve named in question 21 allows cylinder extension in one position and cylinder retraction in the second position?

A

Two position

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21
Q

There are five commonly available center positions for a three-position, four-way directional control valve. List these.

A

Closed

open

tandem

floating

regenerative.

22
Q

What are the five general categories of actuation methods used to shift directional control valves?

A

Self actuation

manual operation

mechanical operation

pilot

23
Q

What is often used on the ends of the spool in directional control valves to automatically return the valve to the normal or restart position whenever the activation force is removed?

A

Springs

24
Q

List the three factors that control the rate of fluid flow through an orifice.

A

Area of the orifice opening

pressure difference between the inlet and outlet sides of the opening

viscosity of the fluid.

25
Q

Restrictor-type, noncompensated flow control valves provide a consistent flow rate as long as the load on the system is constant and the ______ of the fluid does not change.

A

Temperature

26
Q
  1. An integral ______ valve is often used with needle valves to allow unrestricted reverse flow around the metering orifice.
A

Check

27
Q

A(n) ______ flow divider valve allows pump output to be divided between system subsystems using a preselected ratio.

A

Proportional

28
Q

Control valves allow a hydraulic system to produce the type of _______ and level of ______ needed for machine operation.

A

Motion

Force

29
Q

What is the primary purpose of pressure control valves in a hydraulic circuit?

A

Protect the system from excessive pressure

30
Q

The _______ serves as the holder of all the working elements of the valve.

A

Valve body

31
Q

Define fixed orifice

A

Small holes machined into the valve body

32
Q

What are two sources of internal force typically used to position control valve elements

A

Springs

Pilot pressure

33
Q

Why is it important to remove fluid that leaks into internal clearances and control chambers

A

Can cause valve to malfunction

34
Q

When a valve is classified as normally open or closed, it is only in relation to the position of the internal elements when the system is _______.

A

Shut down

35
Q

Four basic tasks that fluid pressure perform in the operation and control of a hydraulic system.

A

Open and close control valve

Remote operation

36
Q

Define pressure override

A

Difference between cracking and full flow pressure

37
Q

What are two basic internal modes of operation for pressure control valves.

A

Direct operation

Balancing piston

38
Q

Name the two types of pressure control valves that are used to prevent damage to hydraulic systems in cases where the relief valve fails

A

Safety valve

Fuses

39
Q

Safety valves are typically set at a pressure _______ above the setting of the primary system relief valve

A

25 percent

40
Q

Multiple operating steps actuated in a preselected order can be obtained in a hydraulic circuit by the use of ______ valves.

A

Sequence

41
Q

Describe what is needed to lower a load that is held in position by a counterbalance valve

A

Use the weight of the load

42
Q

Unloading pressure control valves are commonly found in hydraulic circuits that use accumulators or _______.

A

Dual pumps

43
Q

A pressure reducing valve is normally open and must be _______ drained.

A

Externally

44
Q

A ________ valve is used primarily to block fluid flow through a hydraulic system line.

A

Shut off

45
Q

A three way directional control valve has four ports. Describe what each port is connected to.

A

Pump discharge

Motor inlet

Motor outlet

Reservoir inlet

46
Q

The _______ method of directional control activation uses system pressure, which may be remotely sensed, to shift the valve.

A

Piloting

47
Q

Which type of three position, four way directional control valve has a middle position with the pump, reservoir, and actuator ports connected?

A

Floating center

48
Q

In some directional control valves, the spool is held in position by a locking device called _______.

A

Detent

49
Q

What are the two general operating designs of flow control valves?

A

Restrictor

Bypass

50
Q

The simplest of the adjustable, no compensating flow control valves is a ________.

A

Needle

51
Q

Two ways to accomplish temperature compensation in a flow control valve.

A

Sharp edged orifice

Heat sensitive metal rod

52
Q

During system operation, when actuator pressure requirements are below the cracking pressure of the relief valve, a _______ type flow control valve directs any excess pump output flow directly to the reservoir via a port on the valve.

A

Bypass

Hydraulics (1 decks)

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