Chapter 10 Flashcards

(52 cards)

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?

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
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.
Temperature
26
29. An integral ______ valve is often used with needle valves to allow unrestricted reverse flow around the metering orifice.
Check
27
A(n) ______ flow divider valve allows pump output to be divided between system subsystems using a preselected ratio.
Proportional
28
Control valves allow a hydraulic system to produce the type of _______ and level of ______ needed for machine operation.
Motion Force
29
What is the primary purpose of pressure control valves in a hydraulic circuit?
Protect the system from excessive pressure
30
The _______ serves as the holder of all the working elements of the valve.
Valve body
31
Define fixed orifice
Small holes machined into the valve body
32
What are two sources of internal force typically used to position control valve elements
Springs Pilot pressure
33
Why is it important to remove fluid that leaks into internal clearances and control chambers
Can cause valve to malfunction
34
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 _______.
Shut down
35
Four basic tasks that fluid pressure perform in the operation and control of a hydraulic system.
Open and close control valve Remote operation
36
Define pressure override
Difference between cracking and full flow pressure
37
What are two basic internal modes of operation for pressure control valves.
Direct operation Balancing piston
38
Name the two types of pressure control valves that are used to prevent damage to hydraulic systems in cases where the relief valve fails
Safety valve Fuses
39
Safety valves are typically set at a pressure _______ above the setting of the primary system relief valve
25 percent
40
Multiple operating steps actuated in a preselected order can be obtained in a hydraulic circuit by the use of ______ valves.
Sequence
41
Describe what is needed to lower a load that is held in position by a counterbalance valve
Use the weight of the load
42
Unloading pressure control valves are commonly found in hydraulic circuits that use accumulators or _______.
Dual pumps
43
A pressure reducing valve is normally open and must be _______ drained.
Externally
44
A ________ valve is used primarily to block fluid flow through a hydraulic system line.
Shut off
45
A three way directional control valve has four ports. Describe what each port is connected to.
Pump discharge Motor inlet Motor outlet Reservoir inlet
46
The _______ method of directional control activation uses system pressure, which may be remotely sensed, to shift the valve.
Piloting
47
Which type of three position, four way directional control valve has a middle position with the pump, reservoir, and actuator ports connected?
Floating center
48
In some directional control valves, the spool is held in position by a locking device called _______.
Detent
49
What are the two general operating designs of flow control valves?
Restrictor Bypass
50
The simplest of the adjustable, no compensating flow control valves is a ________.
Needle
51
Two ways to accomplish temperature compensation in a flow control valve.
Sharp edged orifice Heat sensitive metal rod
52
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.
Bypass