水压力（hydraulic pressure）

After installing a new hydraulic pump in a system, what special attention should be given to the hydraulic system?

A.The relief valves in the system should be readjusted

B.The filters and strainers should be checked frequently

C.All system pressure should be readjusted

D.The system should be drained and renewed with a fluid of different operating characteristics

The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by_______.

A.large conical springs

B.compressed air pressure

C.hydraulic pressure

D.exhaust gas pressure

Which of the listed pressure control valves would be used to establish the maximum operating pressure of a hydraulic system?

A.Pressure-reducing valve

B.Unloading valve

C.Counterbalance valve

D.Pressure-relief valve

A certificated lifeboatman assigned to command the lifeboat must ______.

A.be the first individual to board the craft

B.drain the hydraulic pressure before lowering the craft

C.have a list of the persons assigned to the liftboat

D.all of the above

Hydraulic machinery failures are commonly caused by contamination of the hydraulic fluid and ______.

A.fluid friction

B.fluid turbulence

C.component misalignment

D.pressure surges

Before performing any maintenance on a hydraulic system storing energy in an accumulator, you should

A.pressurize the system to test for leaks

B.bleed off all pressure within the system

C.operate the machine until it reaches normal temperature

D.disconnect the pump pressure control switch

What type of valve is used to direct the flow of hydraulic fluid?

A.relief valve

B.direction control valve

C.stop valve

D.pressure control valve

Air trapped in the hydraulic fluid of a steering system may be indicated by

A.the steering pumps overspeeding

B.a jammed open relief valve

C.a constantly occurring improper rudder response

D.excessive ram pressure

Pressure drop in an operating hydraulic system is developed ______.

A.only by the pump as its primary function

B.by resistance to the fluid flow through the system

C.by the thermal input to the system's fluid

D.solely(单独地) by the charge applied by the accumulators