Fluid Powers Final

Both hydraulic and pneumatic systems provide an easy means of multiplying and controlling _______________    and ______________________________.

torque, force

Clean operation with minimum fire hazards are characteristics of which fluid power system(s)?

pneumatic

The ___________________ fluid power system can usually provide the best solution where lightweight and easily handled tools are a requirement.

pneumatic

A ___________ cylinder can exert force during both the extension and retraction strokes.

double acting

A ____________________ valve found in some power units is set at a pressure slightly higher than the normal system operating pressure for protection if the relief valve fails.

safety

A ____________________    valve is used in the design of fluid power system filters to route fluid around

the filter element if it becomes clogged during system operation.

bypass

A consideration when selecting pneumatic tools is the safety factor involved in the storage and movement of

       the  ____________________

pressurized air

A cylinder that has externally mounted metal rods holding the ends on the barrel is called a(n) ____________________cylinder.

tie-rod

A force of 50 pounds applied over a distance of 20 feet in 2 minutes produces ____________________ foot- pounds per minute of power.

500

A lever in which the fulcrum is located between the effort and load arms is called a(n)

first-class lever

A major advantage of using a pressure-compensated pump in a hydraulic system is reduced  ____________________ consumption.

energy

A major difference between hydraulic and pneumatic systems, which is important to safety, is the            characteristic of gases.

compressibility

A motor in which the output shaft bearings are side loaded is classified as a(n)_____________ design.

unbalanced

A primary disadvantage of petroleum-based hydraulic fluids is low resistance to __________________ , which makes them unsuitable in many applications.

fire

A(n) ____________________ is used on reservoirs to allow the tank to take in or release air as the fluid level changes during system operation.

vent

A(n) ____________________ standard pipe thread should be used when assembling pipe to prevent leakage when the joint is placed under high system pressure.

Dryseal

A(n) ____________________ is used to connect the cylinder barrel and the power output shaft of a bent- axis hydraulic motor.

universal joint

A(n) ____________________ is an actuator that converts energy stored in the system fluid into linear motion.

cylinder

According to Bernoulli’s theorem, each time the diameter of a line in a fl uid power system

decreases, the velocity of the fl uid in the line ______ and the pressure ______.

increases, decreases

All fluid power systems should always be treated as if they are ___________________ and ready to function.

pressurized

An example of torque is the ___________________ applied to the shaft of a machine by a prime mover.

force

As the displacement is reduced in a variable-displacement vane motor, the speed of the motor increases, while the potential ____________________ output decreases.

torque

Define standard.

The preselected factors used as the basis for comparing items or procedures.

During the ______ phase of basic pump operation, the pressure in the pumping chamber

is below atmospheric pressure.

intake

Energy that is lost because of high flow resistance produces ____________________, which can cause system operating problems.

heat

Excessive fluid velocity in a working line may produce ___________________ flow, which can result in reduced system efficiency.

turbulent

Flexible hydraulic hose is desirable in systems involving movable machine members or where

       severe  ____________________ is a problem.

vibration

Fluid power system filters may be located in one or more of three typical locations. List these three locations.

working lines, Intake lines, return lines

Fluid power systems are made up of ____________________  containing parts designed to perform specific tasks.

component groups

Fluid power systems use_____________fluids to transmit power.

pressurized

Improving surface tension characteristics increases the rate at which water separates from hydraulic oils and collects in the ____________.

reservoir

In a basic hydraulic system, actuator extension speed is controlled by placing a__________ in the line between the directional control valve and the actuator.

flow control valve

In a hydraulic system drawing, multiple ____________________ symbols are used to terminate fluid return lines to reduce the number of lines returning to the main reservoir.

reservoir

In general, the reservoir for a stationary industrial system should have a storage capacity ____________________times the flow rate of the pump.

3

In the inline piston motor, a(n) ____________________ is used to change the linear movement of the pistons to rotary motion of the power output shaft.

swash plate

In the inline piston motor design, the centerline of the pistons and cylinders is inline with the

centerline of the __________________.

shaft

It is considered good practice to install  ____________________ devices on pressure and flow control valves to prevent operators from resetting the system to unsafe pressure and flow levels.

tamper-resistant

It is the responsibility of the ____________________ to learn and follow the safety procedures needed to perform a job safely.

employee

It is typically recommended that the average fluid velocity in a hydraulic system working line should not exceed            feet per second.

20

List the three basic configurations used to mount cylinders to equipment.

fixed centerline, fixed non centerline, pivoting centerline

List three safety related rules concerning the location of machine controls on equipment involving fluid power components.

controls should be located away from all moving machine components, controls should not interfere with the operator’s normal work space or work surface , easy access for maintenance should be part of the control design.

Name the four categories of data typically found in information sheets provided by pump manufacturers.

General specifications, application information, performance data , installation drawings,

Name the three basic components that make up a hydraulic cylinder.

piston, rod, barrel

Name the three most common, basic designs of hydraulic motors.

gear, vane, and piston

Name the two pivoting-centerline cylinder-mounting methods that allow the cylinder to follow the arc made by a pivoting machine member.

Clevis mount, trunnion mount.

Name three common ways that water can enter a fluid power system and contaminate the system fluid.

Condensation in the reservoir, exposure to weather in exterior installations, water sprayed on the equipment for cleaning purposes

Overall efficiency and volumetric efficiency are typically found in the ____________ section of

      pump information sheets.

performance data

Piston pumps can function in systems requiring operating pressures as high as  ____________________         psi or higher in some cases.

10,000

Shifting a(n) ____________________ control valve creates a new fluid flow path in the system, which

controls actuator movement.

directional

Standard atmospheric pressure is equivalent to a column of mercury  ____________________ inches tall.

29.92

Symbols are shown in the  ____________________ position, unless they are part of a circuit diagram showing a sequence of operation.

at-rest or neutral

The _____________________ fluid power system is usually selected when an application requires a high operating pressure.

hydraulic

The amount that the viscosity of a hydraulic fluid will change as the temperature of the

fluid changes is indicated by a _______________ number.

viscosity index

The balanced-vane motor configuration places a balanced load on the ___________________ of the motor.

bearings (or shaft bearings)

The basic actuators used in fluid power systems are ______ and ______.

cylinders, motors

The basic pressure control device that sets maximum workstation operating pressure in a pneumatic system is called a(n) ______________.

pressure regulator

The friction between two surfaces can easily be reduced by placing a layer of liquid, called a(n) _________, between them.

film

The inlet line of a hydraulic pump should be sized to eliminate high fluid velocities and pressure drops. What is the minimum size for the inlet line?

It should be no smaller in diameter than the diameter of the pump inlet.

The junction of lines is indicated by a(n) ____________________ placed at the point where the lines meet.

dot

The key technical elements of a standard are found in the ________________________ section of the document.

general rules

The kinematic viscosity variation of a fluid between 40° and 100° Celsius is indicated by the __________.

viscosity index number

The modes of operation of multiple-position ______ are shown by using a box for each of

the operating positions.

control valve

The most popular hearing-protection devices are ____________________ , which are both inexpensive and inconspicuous to wear.

earplugs

The most popular hydraulic pump uses ____________________ gears as the primary elements of the pumping mechanism.

external

The physical movement of a gas or liquid is involved in the  ___________________ mode of heat transfer.

convection

The pistons of the inline axial-piston pump are powered by an angular device called a(n) _______________plate.

swash plate

The primary function of the liquid in a hydraulic system is to:

Transmit energy to do the work the system is designed to complete.

The simplifi ed symbol for a flow control valve indicates that the valve is ______ if an

arrow at a 45° angle appears across the restrictive orifi ce of the valve.

adjustable

The size of hydraulic system tubing is indicated by the actual  ____________________ of the tube.

outside diameter

The symbols for the devices used to operate directional control valves are drawn on the end of the basic valve symbol.

These devices are referred to as _________________________________.

control mechanisms

The temperature of the fluid in the reservoir of an operating fluid power system is ideally between

       ____________________ and  ____________________ degrees Fahrenheit.

100:140

The tendency of a body to remain in motion once it has achieved operating speed is known as ______________.

inertia

The tendency of a body to remain in motion once it has achieved operating speed is

known as ______.

inertia.

The two most common prime movers used in a hydraulic system are a(n) ____________________ and a(n)  ____________________         .

electric motor and internal combustion engine

The type of axial-piston pump that is considered more rugged in performance is the design

bent-axis

Three items essential to human existence and comfort that have been closely related throughout history to the development of fluid power are:

Transportation, movement of water and power generation and transmission.

Tube fittings are attached to system components by either tapered pipe threads or straight threads sealed by a flat compression washer or a(n) ________________________ .

O-ring

What are the symbols called that are really miniature section drawings of component parts?

cutaway symbols

What are the two reservoir configurations that are suitable for use with a pump that requires a positive pressure on the inlet line?

L-shaped and overhead

What determines the output flow rate of a hydraulic pump?

The size of the pumping chamber and the speed of the prime mover.

What determines the pressure against which the pump in a hydraulic system must operate?

The resistance to fluid flow in the system and the force that can be applied to the piston.

When maintenance staff is working on equipment, ____________________ devices are commonly used so

 the machine cannot be accidentally turned on.

lockout

Which fire-resistant fluid is similar to automotive antifreeze?

polyglycol

Which hydrostatic transmission type typically combines the pump, motor, fluid lines, valving, and accessories into a single housing?

integral construction

Who is credited with the invention of the cup seal, which led to the

development of the first functional hydraulics press.

Joseph Bramah; Henry Maudslay

____________________ circuits are used in closed-loop hydraulic systems to make up fluid lost from leakage during system operation.

replenishment

A 3/2 Directional Control Valve has __________.

3 ports and 2 positions

A _____________ accumulators use the force of gravity to allow the storage of energy in a hydraulic system.

weight-loaded

A blocked drain on a sequence valve will cause

the valve to stay closed

A check valve is sometimes used with a sequence valve to

allow reverse flow

A common cylinder feature option to prevent end cap damage and failure is?

cylinder cushions

A directional valve is used to

Change the direction of the fluid

A double acting cylinder will extend when oil flows into

the cap end

A flow control valve is a combination of.

needle valve and check valve,

A meter-in flow control valve controls the speed of an actuator by applying back  pressure to the actuator by

restricting flow to the actuator.

A pump produces

flow

A reverse flow check may be needed with a PRV because

A pressure spike could close the PRV

A(n) ______ valve is a direct-operated valve that fully opens as soon as the maximum allowable system operating pressure is reached.

safety

Air pressure at Sea Level =

14.7 pounds per square inch)

Another name for a cylinder would be

an actuator