Hydraulics Final Exam

List the three factors control valves regulate to produce a desired performance in a pneumatic circuit.

1. air pressure 2. direction of airflow 3. the rate of air flow

What are three internal components that contribute to containment in the hydraulic fluid as they wear?

1. bearings 2. seals 3. packing

Name five places where liquid water may form in the pneumatic system.

1. distribution lines 2. intercooler 3. moisture separator 4. receiver 5. aftercooler

Name three factors that hydraulic safety circuits ensure.

1. equipment can be operated without injury 2. equipment cannot unexpectedly operate 3. costly equipment is protected against excessive pressure and operating rates.

List three performance factors that make piston air motors desirable in many pneumatic system applications.

1. high power output 2. high starting torque 3. accurate speed control.

what are the three pressures used to establish the usable volume of an accumulator?

1. maximum operating pressure 2. minimum operating pressure 3. pre-charge pressure

List four basic tasks that fluid pressure performs in the operation and control of a hydraulic system.

1. opening a control valve to limit the maximum pressure in a system 2. closing a control valve to provide a reduced pressure in a small part of a system 3. remotely operating a control valve to promote effective operation to increase operator safety 4. operating a compensating device to provide a source of uniform fluid flow

List the three designs of gas-charged accumulators used in hydraulic systems

1. piston 2. bladder 3. diaphragm types

List the three general locations for a filter in a hydraulic system.

1. pump inlet line 2. system working lines 3. return lines

list three results that may occur if pressure and flow variations are great enough in a system under varying load conditions.

1. reduce the efficiency of the system 2. cause damage to system components 3. can harm the machine or workers.

Name three techniques used to assure a positive seal between the tips of the vanes and the walls of the internal chamber of a vane air motor.

1. springs 2. air pressure 3. centrifugal force.

Name two things that occur when warm, humid, high-pressure air cools in the distribution lines of a pneumatic system.

1. the pressure of the compressed air drops 2. if the temperature reduces to dew point liquid water can form in the distribution lines.

identify the two factors that are critical to selecting the actual sizes of the lines used in a air distribution system.

1. the total air consumption of all actuators 2. pressure drop caused by the lines and fittings.

standard atmospheric pressure is _____________ pounds per square inch at sea level

14.7

An air motor should be sized to operate on what fraction of the workstation pressure to allow for the extra power needed for starting loads and unexpected overloads?

2/3

____________ percent or more of the prime mover horsepower is converted into heat that raises the fluid temperature in a hydraulic system.

20

Accumulators are available with rated fluid capacity ranges from under 1 pint to over ________ gallons, although some specialized accumulators may have much greater capacities.

200

For all hydraulic systems, the minimum filtration level recomended by the national fluid power Association is _________ microns.

25

safety valves are typically set at a pressure ___________ % above the setting of the primary system relief valve.

25

The atmosphere blankets the Earth with a layer of gasses approximately __________ miles deep

360

In the _____________ flow control circuit, the flow control valve is placed between the outlet port of the actuator and the directional control valve.

Meter out

Control valves allow a hydraulic system to produce the type of ________ and level of ___________ needed for machine operation

Motion, force

___________ pneumatic cylinders can be operated using compressed air thar does not contain oil.

Piston

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

To protect the overall system from damage from excessive pressure build up by limiting maximum operating pressure.

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

Valve body

____________-loaded accumulators use the force of gravity to allow the storage of energy in a hydraulic system.

Weight

A(n) ___________ process is one that is completed without heat gained from or lost to surrounding materials.

adiabatic

The process that assumes all heat is retained in the air during compression is known as ______________ compression.

adiabatic

In addition to air storage, the reciever dampens air ___________ caused by compressor operation.

air pulsation

In the high-low pump design, when is the high volume pump discharge routed to the reservoir?

at the beginning

______________ valves may be adjusted from the fully open position to the fully closed position by turning the control handle only 90° (1/4 turn).

ball

Which flow control circuit is considered the most energy efficient?

bleed off

When a filter becomes clogged with contaminants the __________ valve opens to allow system fluid to flow past the filter.

bypass

The _____________ compressed-air-distribution system distributes air from a single location to all workstations in a facility.

centralized grid

A maximum pressure lower than the relief valve setting may be obtained by using a(n) ____________ valve in a circuit.

compound relief valve

what is the most common method used to control the maximum operating pressure in the distribution line of a pneumatic system?

compressor-capacity control

In a gas-charged accumulator, the volume of the isolated gas chamber ___________ as the volume of the system-port chamber increases.

decreases

to trap contaminants, _________-type filters use a mass of porous material that provides many different flow routes.

depth

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

dual pumps

sequence valves must be ___________ drained. explain why.

externally, to allow drainage of fluid even when working lines in either side are pressurized.

In air-cooled, reciprocating compressors, the cooling air is often circulated by a fan that is an integral part of the compressor ____________.

flywheel

The air-consumtion rate of a pneumatic cylinder during operation is expressed in cubic feet of ____________ per minute.

free atmospheric air

The _____________ filtration routing method requires the use of a filter bypass valve to prevent the development of excessive pressure drop across a clogged filter.

full-flow filtration

robots often make use of a pneumatic ______________ to pick up and place materials.

gripper

In a meter-out flow control circuit controlling the extension of a single-acting cylinder the pressure in the rod end chamber of the cylinder may be _____________ than the maximum pressure setting of the relief valve.

higher

The volume of fluid available from an accumulator is greatest if the unit is charged and discharged as a(n) _________ process.

isothermal

What is the most common application of a check valve in a hydraulic system?

Allowing free flow of fluid through a line in one direction, while preventing reverse flow in that line.

Which design of air distribution system is generally considered to provide maximum airflow with a minimum of flow resistance?

loop system

The only shut-off valve that is recomended for metering airflow in a pneumatic system is the ___________ valve.

needle valve

The two most common basic flow control devices used in pneumatic system are fixed sized orifices and ____________ valves.

needle valves

The first factor contributing to the quality of compressed air that can be produced is the condition of the ___________ at the system air intake

Atmospheric air

The air we breath and use as the source of air for pneumatic systems contains several gasses name the gasses and the percentage at which they exist in the atmosphere.

nitrogen 79%, oxygen 20%, and others 1%

Dynamic compressors can also be classified as ____________-displacement compressors

non-positive

Compressed-air units may be classified as a(n) ___________ or _____________

portable air unit, central air supply

Internal geometry and system ___________ determine the force output of a hydraulic cylinder or motor.

pressure

Air or _______ should never be used in gas charged accumulators.

pure oxygen

A(n) _______________ valve increases the rate at which air is exhausted from a cylinder.

quick-exhaust valve.

The simplest compressor ik both design and operating theory is the single-acting, _______________ compressor.

reciprocating compressor

______________ refers to the amount of water vapor actually carried by a volume of air compared to the maximum amount it can carry at the specified temperature.

relative humidity

The continuous rotating motion of the compression elements identifies a(n) _____________ compressor design.

rotary

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

safety valve

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

shut down

A(n) __________ valve is used primarily to block fluid flow through a hydraulic system line.

shut-off

The pressure setting of regulators using a flexible diaphram is set by controlling the _________ applied to the diaphragm

spring or screw

A(n) ____________ is often considered a course filter that removes only the largest of the contaminants that have entered the hydraulic fluid.

strainer

If a system component requires a higher level of filtration than the system in general, where would an additional filter be placed?

system working lines

The fluid conditioning system of hydraulic powered equipment provides fluid that is clean and maintained at an acceptable operating ____________.

temperature

what happens to the compressed air used to operate an actuator after it is returned to the directional control valce.

the air can directly pass to the atmosphere

what determines the speed of an air motor?

varying speed air pressure and air flow rates changes the output speed and torque of the motor.

Remote control of pilot-operated relief valves can be easily achieved by using the ______________ feature of the valve.

vent

How is rapid cylinder advance created in a regenerative-cylinder-advance circuit?

when the fluid in the rod end of the cylinder is directed to the blind end to increase the amount of flow extending the cylinder.

An accumulator permits __________ to be absorbed and stored in a hydraulic system.

Energy

what determines the force produced by a pneumatic cylinder?

The area of a cylinder piston or diaphragm and the air pressure in the system.