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101 Cards in this Set
- Front
- Back
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Hydrualic Motors convert...
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Hydraulic pressure into rotary mechanical motion.
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To reverse the motion of a Hydraulic motor...
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Reverse the direction of fluid flow through the motor.
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To change the speed of a Hydraulic motor...
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Change the flow of fluid through the motor.
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In a hydrualic motor, any leakage past the pistons...
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must flow through the case drain port to return.
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What does an accumulator do?
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Store a volume of fluid under pressure, provide space for thermal expansion, and act as a cushion against pressure surges.
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How are accumulators rated?
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By capacity in cubic inches and by system operating pressure in pounds per square inch.
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A piston accumulator
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uses dry air or nitrogen to act like a spring.
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A self-displacing accumulator is
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a piston accumulator with four seperate chambers for air, pressure, storage, and venting.
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The self-displacing accumulator acts as a...
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conventional accumulator to store a volume of fluid under pressure.
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Under normal conditions, the self-displacing accumulator acts as a
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system resevoir.
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As a pump rotates,
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it produces fluid flow.
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A fliter assembly provides
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an adequate control of the contamination problems encountered during normal system operation.
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A typical hydrualic filter assembly consists of three basic parts:
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The head, the element, and the bowl.
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The filter head
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is normally mounted to the aircraft structure by mount bolts.
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The bypass relief valve
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routes fluid from the inlet port to the out let port if the filter element is clogged. (Allows fluid to flow to a system despite a clogged filter.)
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Differential Pressure Indicator (DPI) indicates...
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when a filter element is creating a difference between the fluid entering the element and the pressure leaving it. (The filter is clogged. The inlet pressure will cause the DPI to pop out.)
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Shutoff diaphragm
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is used to prevent entry of air into the system and loss of fluid during maintenance (Such as replacing the filter element) (is located in the filter head)
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The filter elements are rated...
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according to the amount of dirt or contaminates that they can filter.
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A filter element can be either ________ or _______ .
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Absolute or nominal.
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The filter bowl is
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a bowl that fits over the element and screws into the head.
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Any contamination that enters with the fluid through the inlet port of a filter
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will be held or trapped on the outside of the filter element.
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Bypass fluid-flow is when...
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fluid pressure builds up enough to off-seat the bypass valve. (Allows contaminated fluid to enter the system. Causes the DPI to pop)
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Fluid coolers
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are used in hydaulic systems to lower the temperature of the fluid within the system.
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Fluid coolers are normally located...
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in the return lines to cool the fluid as it flows back to the resevoir.
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A fluid cooler bypass valve is installed to..
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bypass the fuel cooler when the temperature of the air in the air cooler is low.
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What do manifolds do?
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Manifolds provide a location where common fluid lines can come together.
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Mainfolds help conserve...
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space in the aircraft and permit ease of unit removal and replacement.
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Manifolds are designed so that any...
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valve, filter, or quick disconnect can be removed without disturbing any other part of the assembly.
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What components are used to regulate the flow of hydrualic fluid?
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Check valves, shutoff valves, and relief valves.
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Check valves allow...
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flow in one direction and no flow in the other.
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What are the two types of check valves?
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Automatic and manual
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Automatic check valves contain
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a seat onto which a poppet (Ball, cone or flapper) will be forced by spring tension.
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Manually-operated check valves (MOC valves) can be...
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unseated mqanually to permit free-flow of fluid in both directions.
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With the handle of a MOC valve in the closed position,
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the MOC valve acts as an automatic check valve.
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If pressure rises too high, the relief valve will...
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send fluid back to the return.
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Shutoff valves are used to
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contorl the flow of fluid.
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If a shutoff valves is open or closed,
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they will allow fluid flow or shutoff fluid flow, respectively.
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A manually-operated shutoff valve is used to...
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vary the amount of fluid-flow by partially closing or opening the valve.
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The three types of shutoff vlaves are:
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manually-operated, motor-operated, and solenoid-operated.
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The manually-operated shutoff valve is an...
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adjustable flow-control valve.
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When power is applied to a solenoid-operated shutoff valve,
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the solenoid creates a magnetic field that pulls a poppet off a body seat, thus allowing fluid-flow from the inlet port to the outlet port.
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The motor-operated shutoff valve can be used to...
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shut off the flow of fluid to the engine in case of an engine fire.
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Relief valves are
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pressure-limiting devices.
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Main-system relief valves limit...
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maximum pressure reached by dumping the excess pressure into the return line.
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The main-system relief valve must be large enough to...
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pass the pump's full output back to return. (If it weren't large enough for this, pressure would continue to build up and eventually rupture the line.)
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Return line pressure is caused by...
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resistance in the return line.
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Thermal Relief valves are designed to...
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relieve only small quantities of fluid due to thermal expansion. (One ore two drops)
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Balanced outlet relief valves are constructed so that...
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back pressure cannot affect the operation of the valve. (eliminates the effective area that back pressure can act on)
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The most common problem associated with relief valves is..
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internal leakage.
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Why do nonpressurized resevoirs have space above the fluid?
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To assist the fluid in purging air bubbles from the system
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What prevents foregn material from entering the resevoir during servicing?
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Finger screens
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What are the two main reasons for pressurizing a resevoir?
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esuring positive fluid flow, and preventing foaming at high altitudes.
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How is a hydraulic pressurized resevoir serviced with fluid?
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Through a self-sealing filler valve.
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What is used to prevent damage to a hydraulic pressurized resevoir during servicing?
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A relief valve.
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What is the first thing you must do in order to service or perform maintenance on an air-pressurized resevoir?
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Depressurize the system
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What component in a pressurized hydraulic resevoir system controls the air pressure within safe limits?
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Air pressure regulator
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In an air-pressurized resevoir, where is the air for resevoir pressurization usually taken from?
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Engine bleed air
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If either check valve inside the hand pump malfuntions, what would be the indication, if the pressure line did not have a third check valve?
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The hand pump would become inoperative.
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What is the drawback of a constant-volume pump?
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It will eventually build up enough pressure to burst lines and containers.
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What is the thinned portion on the drive shaft of a gear-type pump called?
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Shear section
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On a vane-type pumpe, what keeps the vanes against the housing wall?
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Springs
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In the constant-volume piston pump, what drives the cylinder block?
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Universal links
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Why does a constant-volume piston pump always have a constant intake and output of fluid?
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There are always pistons between the upper and lower position.
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What happens to the excess case drain pressure in a constant-volume pump?
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It is routed back to the intake side of the pump.
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Describe the suction boost pump's impeller.
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A paddle wheel that slings fluid outward from the center.
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What does the suction boost pump do for engine-driven pumps?
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Ensures an adecquate supply of fluid to the engine pump.
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What regulates pressure in a variable-volume pump?
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An integral flow-control vlave or compensator.
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What is the main difference between a Vickers stroke-reduction pump and a constant-volume pump?
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The angle between the drive shaft and cylinder block.
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When the system is at 0 PSI, the Vickers pump's cylinder block and yoke are in what position to provide full-flow?
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Extreme angle position.
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Do the pistons have a stroke when the Vickers pump reaches the ZERO FLOW point?
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Nope.
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The Kellogg pump is made up of two major component grups. What are they?
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The rotating group and the pressure-compensating group.
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What is the purpose of the creep plates in Stratopower pumps?
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Cooler operation and more even wear on the cam.
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Describe the pistons of the Stratopower pump.
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Pistons with fairly large hollow centers connected with cross-drilled holes.
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If the Stratopower pump sense a pressure increase, what component is acted on to reduce the pressure?
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Compensator piston
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On the Stratopower pump, which way would you turn the adjusting srew to increase pressure?
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Clockwise
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List the differences between a hydrualic pump and a hydraulic motor.
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Flow is directed into the motor rather than from it. The motor does not have a foot valve.
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What can be used to control the speed of a hydrualic motor?
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Flow-control valve
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Explain the principle of a jackscrew.
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The screw turning causes the nut to move back and forth.
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Which accumulator has a drilled passageway in the piston for lubrication?
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Piston
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Which accumulator has four separate chambers and two pistons connected together by a rod?
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Self-displacing
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Which chamber of the self-displacing accumulator is serviced with fluid when the supply system is serviced with the hand pump?
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Storage
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What is the purpose of a compensator in a self-displacing accumulator system?
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It spring forces the fluid from the compensator.
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In the self-displacing accumulator system, where is the relief valve located?
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Between the pressure and return line.
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What is meant by micron rating of a filter element?`
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The amount of dirt or contaminates they can filter.
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What are the two ways fluid can flow through a filter assembly?
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Normal and bypass
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What is routing the hot hydraulic fluid lines through the fuel system advantageous?
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Heated fuel will burn more efficiently.
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Why is the spring of a check valve relatively weak?
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It's only there to keep the poppet (ball, cone, or flapper) agains the spring.
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Which type of check valve has a ball follower? What is it used for?
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Automatic check valve have the ball follower and it's used to prevent the pall from cocking to one side.
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What determines the purpose of the slenoid-operated shutoff valve?
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Location in the system.
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Which type of shutoff valve has an indicator to show if it is closed or open?
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Motor.
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What causes the motor-operated shutoff valve to shut off when it reaches the fully-open or flully-closed position?
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Limit switches
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What is back pressure?
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Return line resistance
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The type of selector valve used in a system depends upon the...
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type of system, type of actuators, and teh manufacturer's requirements.
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A poppet type manual selector valve has four ports:
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One pressure, one return, and two alternating.
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The poppets are arranged so that the
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rotation of the cam will open the proper combination of poppets to direct the flow of fluid in the desired direction.
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The Manual selector poppet type valve has three positions:
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One neutral position and tow working positions.
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In the neutral position of the Manual selector poppet type valve, the lobes on the cam
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are not contacting any of the poppets.
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When all poppets are seated in the Manual selector poppet type valve,
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There is no flow of fluid through the valve.
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When the Manual selector poppet type valve is in a working position, the lobes of the cam are...
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unseated from one pressure poppet and one return poppet.
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One of the major advantages of the Manual selector slide type valve is it's
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metering ability. It does not have to be positioned all the way open.
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Another name for the Manual selector slide type valve is the
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metering valve.
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