ignition may be delayed because the ______.
A. cylinder compression pressure may not be high enough B. cylinder compression temperature may be too high C. fuel oil injection pressure may not be high enough D. scavenge and purge process is incomplete
25. The intake valves in a diesel engine are reseated by ______.
A. cam followers B. push rods C. combustion gases D. valve springs
26. An over-speed safety device is usually fitted to a generator engine for______ in the event of over-speed.
A. cutting power off the engine B. increasing the fuel pump setting C. braking the crankshaft D. stabilizing the ship speed
二、关联题（每组关联题题干下有4个小题，每小题4个选项）
Each of the engine cylinders is provided with a Bosch, type PF, fuel pump. The fuel pump is a single-acting plunger pump with non-adjustable stroke. The plunger is so accurately ground and lapped that its clearance inside the barrel is only 0.002-0.003 mm. This provides sufficient tightness between plunger and barrel, even at pressures as high as 200-400 bar, without the need for sealing materials. Neither the plunger nor the barrel can therefore be renewed individually. The plunger pressure stroke is produced by a cam on the engine camshaft, whereas the return stroke, the suction stroke is effected by means of a strong coil spring. The top of the pump barrel is closed by a spring-loaded pressure valve, to which the fuel oil pipe for the respective fuel valve on the relevant engine cylinder is connected.
Regulation of the amount of fuel delivered by the fuel pump is achieved by turning the pump plunger, the cylindrical surface of which has a milled recess. The bottom of this recess ends with an edge, which is at right angles to the cylinder generating lines, whereas the top of the recess is limited by a helix. This produces an inclined control edge on the plunger, which also has a narrow longitudinal groove. In the pump barrel are drilled two diametrical holes through which the fuel oil can flow into the fuel pump barrel. The pump barrel is surrounded by a regulating sleeve, the upper end of which is shaped as a toothed rim. The lower end has two lengthwise slots in which projecting lugs on the lower end of the plunger can slide up and down. The end of the regulating rod from the engine governor is designed as a toothed rack that engages with the toothed rim on the end of the regulating sleeve. This makes it possible to turn the pump plunger during engine operation. 1. The fuel pump ______.
A. is of PF type B. is of reciprocating type
C. has an inlet valve and an outlet valve D. A and B are true. 2. The plunger ______.
A. is accurately ground and lapped outside the barrel. B. has a tiny clearance inside the barrel
C. can be renewed individually when worn out D. All of the above are true. 3. Which of the following is true?
A. The stroke of the plunger can be adjusted B. The outlet valve is spring loaded C. The plunger down stroke is accomplished by the spring D. B and C are true. 4. It can be inferred that when moving the rack ______.
A. the sleeve moves up and down B. the plunger moves up and down
C. the effective stroke of the pump will be changed D. All of the above are true.
Lesson 14
Marine Medium Speed Diesel Engine III
单项选择题：
1. Any increase in the exhaust back pressure of a four-stroke/cycle diesel engine will ______.
A. reduce engine horsepower output B. aid in silencing the exhaust noise
C. increase the mean effective pressure D. contribute to effective cylinder scavenging
2. Which of the following can be obtained by means of an indicator card? A. the peak pressure in a cylinder. B. the temperature of the cooling water. C. the fuel consumption. D. none of the above. 3. An automated diesel engine should normally shut down due to______. A. low lube oil temperature B. high ambient air temperature
C. low lube oil pressure D. high exhaust system back pressure 4. A reduction in load on a diesel engine results in ______of speed of the crankshaft. A. a reduction B. an increase C. an outing D. a downwards
5. If the action of the engine indicates that some of the cylinders are not firing, the ones affected may be determined by watching ______.
A. the bad smoke B. the smoky exhaust C. the exhaust temperature D. the peak pressure
6. If ______are taken at regular intervals, any unequal distribution of load will be easily found out.
A. indicator diagrams B. nomo-gram C. temperature readings D. pressure readings
Lesson 15 Marine Pumps
单项选择题：
1. In general, ________ is suitable for delivering small quantities at high pressure. A. reciprocating pump B. gear pump C. centrifugal pump D. vane pump
2. The pumps employed on board ship can be divided into two main categories, i.e. _______ pumps and centrifugal pumps.
A. gear B. non-positive displacement C. positive displacement D. rotary
3. Gear pumps are of positive displacement type pumps because they discharge a near constant amount of liquid ________ pressure. A. depending on B. in relative to C. regardless of D. because of
4. The emergency bilge suction or bilge injection valve is used to prevent _______ of the ship. A. proceeding B. overloading C. collision D. flooding
5. All bilge suctions must be filled with suitable ________, which in the machinery space would be mud boxes positioned at floor plate level for easy access. A. strangers B. relief valves C. emergency valves D. strainers
6. ________ system is arranged to ensure that water can be drawn from any tank or the sea and discharged to any other tank or the sea as required to trim the vessel. A. The domestic water B. Bilge water C. Oil transfer D. The ballast
7. When the water produced from most evaporator is supplied for drinking purpose, it must be treated to ensure it is biologically pure and _______. A. slightly acidic B. slightly alkaline C. no salty D. slightly bitter 8. _______ provides the head or pressure to supply the domestic water where required.
A. The compressed air B. The compressing air C. The transfer pump D. The head tank
9. Under centrifugal pumps are the volute, diffuser, mixed-flow, axial flow and _______ or generative types. A. reciprocating B. hydraulic C. turbine D. vane
10. Where tanks are arranged for either oil or ballast ________ must be fitted in the pipeline.
A. a change-over chest B. a head tank C. an emergency bilge pump D. an air cooler
11. The various pumps and lines are _______ to some extent so that each pump can act as an alternative for another. A. interlocked B. interconnected C. interfered D. interacted
12. ________ are more suitable for large quantities at low pressure. A. Reciprocating pumps B. Rotary pumps C. Centrifugal pumps D. Gear pumps
13. The emergency bilge suction or bilge _______ is used to prevent flooding of the ship.
A. injection valve B. relief valve C. discharge valve D. inlet filter
14. Centrifugal pumps are popular because they are very simple in construction, and produce smooth, constant, ________ discharge. A. non-pulsating B. pulsating C. positive D. non-positive 15. _______ is used for washing and drinking.
A. The ballast system B. The salt water system C. The bilge system D. The domestic system 16. The emergency bilge suction valve is typically used _______. A. to inject cleaning additives when the bilges are extremely dirty
B. when the main condenser becomes fouled, in order to provide additional cooling water circulation
C. to connect the rose box to the independent bilge suction
D. if the bilges become flooded and they can not be emptied by any other means. 17. Which of the following statements represents the advantage of rotary pumps as compared to reciprocating pumps?
A. The high discharge pressure of the rotary pumps permits a larger volume of fluid per unit
time than the reciprocating pumps
B. Rotary pumps are capable of pumping more fluid than reciprocating pumps of the same weight.
C. Rotary pumps occupy only one-half the space of reciprocating pumps
D. Rotary pumps eliminate discharge slippage of the pumped liquid, while this does not hold
true for a reciprocating pump
18. If the discharge valve is closed before the drive motor is stopped, which of the following types of pumps will most likely be damaged? A. Centrifugal B. Gear C. Propeller D. Turbine
19. When operating with a negative suction head, which of the following types of pumps will require priming? A. Reciprocating B. Centrifugal C. Rotary D. Gear
20. An emergency bilge pumping system is provided and should be _______ of the main bilge pumping system, according to the SOLAS 74 Convention. A. dependent B. independent C. in series D. in parallel
21. The pump has a constant stroke and the amount of fuel delivered is regulated by rotating ______ which has a specially arranged helical groove cut into it.
A. the pump cylinder B. the pump cam C. the pump plunger D. the pump roller
22. A vane pump belongs to ______according to its working principle. A. reciprocating pump B. positive displacement pump C. centrifugal pump D. centripetal pump 23. The ______pump is usually used as the lubricating oil pump.
A. turbine B. screw C. vane ejector D. centrifugal
24. If you were operating a centrifugal water service pump with worn wearing rings, the ______.
A. pump would be very noisy B. pump would vibrate excessively C. pump would develop insufficient flow D. stuffing box would leak
excessively
25. A centrifugal pump can?t supply water after starting. You should check the ______. A. discharge valve B. power supply C. packing gland D. bearing lubrication
26. The gear and screw pumps are classified as ______.
A. variable stroke pumps B. multistage pumps C. positive displacement pumps D. triple-ported pumps
27. Centrifugal pumps, however, can be designed with a number of impellers______ to attain a large amount of liquid.
A. in series B. in parallel C. assembled D. together 28. The basic function of the centrifugal pump impeller is to ______. A. directly increase the pressure of the liquid being pumped B. directly increase the velocity of the liquid being pumped C. convert the potential energy of the liquid to kinetic energy D. separate air from the liquid being pumped
29. The pressure head of a water pump is given in the unit of ______.
A. kg B. MPa C. mH 2 O D. none of the above
30. The pump discharge pressure will be considerably higher than the pressure at the ______.
A. pump entry branch B. outlet pipe C. impeller D. None of the above is true.
31. A feed pump for an auxiliary boiler might lose suction if the ______. A. boiler water level is low B. feedwater is too hot C. boiler steam demand is low D. feedwater is too cold
32. To operate a centrifugal fire pump at reduced capacity, you should ______. A. readjust the relief valve B. throttle the suction line C. throttle the discharge valve D. open the priming line
33. Domestic water pump is started automatically by ______which operates as the water level falls to a predetermined level.
A. a level controller B. a temperature switch C. a floating ball D. a pressure switch
34. Lower suction pressure of a pump may be caused by ______.
A. too much air in the pipe line B. closed inlet valve C. empty tank D. leaky pipe
35. Machinery driving fuel oil transfer and fuel oil service pumps must be fitted with a remote means of stopping the machinery from ______. A. within the space concerned B. outside the space concerned C. the throttle station D. within the fire room 36. In a ______the center screw is driven and the outer screws idle. A. single screw pump B. double-screw pump C. triple screw pump D. centripetal pump 37. Which of the following pumps belongs to centrifugal pump?
A. reciprocating pump B. screw pump C. diffuser pump D.