The oil in a cargo winch gear box should be sampled periodically(周期性地) to ______.

试卷相关题目

• 1Positive displacement, helical gear(斜齿轮) pumps are well suited for pumping oil because ______.

  A.stuffing boxes eliminate the leakage problems usually associated with other gear pumps

  B.it is not necessary to closely maintain design clearances with this pump

  C.they are essentially self-priming and produce a high suction lift

  D.these pumps are designed with extreme tooth angles

  开始考试点击查看答案
• 2Among the basic categories of equipment, which of the following are used to allow the hydraulic energy to be controlled、

  A.hydraulic pumps

  B.valves

  C.hydraulic cylinders

  D.hydraulic motors

  开始考试点击查看答案
• 3When securing a flash-type evaporator for an extended period of time, you should ______.

  A.fill the unit with saltwater

  B.fill the unit with descaling compound

  C.completely drain the unit

  D.tightly seal the unit to exclude air

  开始考试点击查看答案
• 4When a vacuum boiling evaporator works, the hot jacket water will pass over the tube stack and ___ the sea water passing through the tubes.

  A.dispose

  B.dissolve

  C.heat

  D.dissipates

  开始考试点击查看答案
• 5Dirty oil must be _____ before being used again.

  A.mixed with clean oil

  B.purified

  C.heated

  D.strained

  开始考试点击查看答案
• 6If an anchor windlass has been idle for some time, you should ______.

  A.repack all valve stems

  B.lubricate it prior to use

  C.replace the foundation bolts

  D.balance the warping heads

  开始考试点击查看答案
• 7A mooring winch should be equipped with mechanical brakes capable of holding ______.

  A.half the breaking strength of the mooring line

  B.the full breaking strength of the mooring line

  C.the maximum expected tension(张力) of the mooring line

  D.50% over the working tension of the mooring line

  开始考试点击查看答案
• 8Hydraulic cranes must be properly warmed-up before being operated because ______.

  A.warm-up allows the hydraulic system to become charged with oil

  B.warm-up allows the relief valves to be properly tested

  C.hydraulic strainers operate only during the warm-up period

  D.hydraulic fluid must be at the proper viscosity

  开始考试点击查看答案
• 9The current flowing first in one direction and then in another is called ____ current.

  A.a rush

  B.an alternating

  C.a direct

  D.an exciting

  开始考试点击查看答案
• 10The frequency of an alternator at a given RPM is determined by the ______.

  A.number of turns of wire in the armature coil

  B.number of magnetic poles

  C.strength of the magnets used

  D.output voltage

  开始考试点击查看答案