3–42.What is the principle function ofthe globe valve?1.To protect the cylinder fromexcessive pressure2.To prevent the liquid in thereservoir from flooding thesmall cylinder3.To make possible several shortstrokes instead of one longstroke with the piston4.To allow the fluid in the largecylinder to flow back into thereservoir3–43.A main ballast tank on a submarineis1.2.3.4.filled with sea water byallowing air to escape from thevents at the top of the tankand allowing water to enterthrough flood ports at thebottom of the tankpumping air from the tank andpumping water into the tankthrough the vents at the toppumping it in through the ventsat the top of the tankpumping it in through the portsat the bottom of the tank3-44.How is the water removed from themain ballast tanks when a submergedsubmarine is surfacing?1.Motor–driven pumps syphon offthe water2.The water is forced out withhigh–pressure air3.The water flows out throughports under the pull of gravity4.Hydraulic pumps syphon off thewater3–45.The variable ballast tanks on asubmarine are filled with sea waterby1.2.3.4.allowing air to escape from thetanks and water to enterthrough flood ports at thebottom of the tankspumping air from the tanks andallowing the water to enterthrough vents at the top of thetankseither of the above methodspumping it in3–46.Hydraulic machines are used aboardsubmarines for1.opening and closing the ventvalves of the main ballasttanks2.raising and lowering theperiscope3.opening and closing the ventvalves of the safety tanks4.all of the above purposesWhen answering items 3–47 and 3-48,*refer to figure 10–14 of yourtextbook.3–47.Thethe1.2.3.4.purpose of an accumulator inhydraulic system is toaccumulate oil as it isreleased from the reservoirkeep the air in the system at aconstant pressureaccumulate excess oil whichflows past check valves in thesystemkeep the oil in the systemunder pressure3–48.To what part, if any, is the pistonin the accumulator fastened?1.A rod which is operated by acrankshaft2.A rod which is activated bypressurized oil in thereservoir3.A main flood valve4.None3-49.Why is it easier to push a 50–poundbarrel up a gangplank than to pusha 50 pound box?1.Rolling friction is less than asliding friction2.The shape of a barrel defiesgravity better than the shapeof a box3.The barrel has a greatersurface to come in contact withthe gangplank4.All of the above reasons28
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