中华人民共和国海船船员适任考试·同步辅导教材
轮机英语自学题库
efficient work stroke per revolution? A.1/2. B.1. C.2. D.3.
注 根据二冲程柴油机原理，每转一转有效冲程的数目是什么？B
237.The cylinder covers are secured by eight elastic holding-down ____ arranged in four pairs.
A.nuts B.screws C.studs D. Flanges 注 缸盖由8个4对弹性垂直往下的双头螺栓紧固。
238.There is a support ring between the cylinder block and the collar of the cylinder liner, thus carrying both the liner and the cylinder cover. It also passes ____ to the cooling bores and to the cover.
A.cooling water B.cooling oil C. refrigerant D.lubricate oil 注 在缸体和缸套凸缘之间有一连接缸套和缸盖的支撑环，它还把冷却水通向冷却孔和缸盖。A
239.The oil sump, a light welded design, is mounted on the engine block from below and sealed by ____.
A. O-ring B.gasket C washer D.packing
注 轻型焊缝结构的油底壳从下面安到机体上，并用垫片密封。B
240.The purpose of the skirt or trunk in four-stroke cycle engines is to act in a similar manner to a ____.
A.crosshead B.crown C.piston rod D.connecting rod
注 四冲程发动机活塞裙部和筒状作用与十字头相似。A 241.The four-stroke cycle engine begins with the piston ________.
A.coming up from the BDC B.coming up from the TDC C.coming down from the BDC D.coming down from the TDC 注 四冲程柴油机开始活塞从上止点下行。D
242.The sealing function of the piston ring is brought about by the gas pressure above and behind the piston ring, which forces it ____ against the bottom of the ring groove, and ____ against the cylinder wall.
A.upwards; inwards B.upwards; outwards C.downwards; inwards D.downwards; outwards 注 活塞环的密封作用是依靠活塞环的上面和内侧的气体压力造成的，该压力迫使活塞环对环槽底部向下压紧并保持对气缸壁向外压紧。D
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English of marine engineering (Operational Level)
243In a diesel engine ,_______offers the heat energy directly ;_______works as working medium and changes the heat energy to mechanical energy. A.the burning of the fuel/medium shaft B.fuel spray/fresh air C.fuel/fuel spray
D.the burning of the fuel /the burned gas mixture
注 在柴油机中，燃油燃烧提供热能；燃气作为媒介并且将热能转化为机械能。D
244.In a diesel engine ,_______works as working medium and changes the heat energy to mechanical energy；_______changes the reciprocating movement to rotary movement.
A.fuel spray/the burning of the fuel
B.the burned gas mixture /connecting rod C.medium shaft/crankshaft
D.the burned gas mixture /piston rod
注 在柴油机中，燃气作为媒介并且（活塞）将热能转化为机械能。连杆将往复运动转化为回转运动。B
245.One of the differences between a two-stroke engine and a four-stroke engine is,____.
A.a two-stroke engine works without exhaust operation B.a two-stroke engine works without compression stroke C.a two-stroke engine works without expansion stroke D a two-stroke engine works without suction operation
注 二冲程机和四冲程机的一个区别是二冲程机工作没有吸气冲程。D
246.One of the differences between a two-stroke engine and a four-stroke engine is,____.
A.a two-stroke engine can't work without cylinders B.a two-stroke engine can't work without pistons C.a two-stroke engine can't work without crankshafts D.a two-stroke engine can't work without a blower
注 二冲程机和四冲程机的一个区别是二冲程机没有辅助鼓风机不能工作。D 247. In a diesel engine, when the fuel is injected into the cylinder,____. A.the piston is just coming upward from the bottom dead center B.the piston has moved about one-fifth of the way up
C.the piston has moved most of the way up and almost reached the TDC D.the piston has just past the TDC
注 柴油机中，当燃油喷入气缸时，活塞已经移动过了大部分行程，几乎要到达
业轮机工程专
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中华人民共和国海船船员适任考试·同步辅导教材
轮机英语自学题库
上止点。C
248.In a two-stroke engine, there are always a series of openings known as ____, and in some circumstances, there are also openings known as ____,in the part of the cylinder liner inside the scavenging air box.
A.scavenging air ports; exhaust ports B.inlet ports; scavenging air ports C.scavenging air ports; inlet ports D.exhaust ports; inlet ports 注 在二冲程机气缸中，总有一系列的开口叫扫气日，并且在某些情况下，也有另外的开口叫排气口位于扫气箱内的气缸套上。A
249.In some type of two-stroke engines, besides some small holes for____, starting valve, safety valve, indicator cock, and so on, there is a large central opening in each cylinder cover for mounting the ____.
A.fuel valves; exhaust valve B.exhaust valves; inlet valve C.fuel valves; inlet valve D.exhaust valves; fuel valve
注 在某些二冲程柴油机中，除了有些孔安装喷油器、启动阀、安全阀和示功旋塞等外，在气缸盖中心有一个大的中心开口用于安装排气阀。A
250.In a two-stroke engine, the piston consists of a lower part, which is named as ____ and usually made of____.and a upper part, which is referred to as ____ and made of ____.
A.low-half; cast iron; top-half; heat-resistant steel B.low-half; aluminum; top-half; stainless steel
C.piston skirt; cast iron; piston crown; heat-resistant steel(耐热钢) D piston skirt; aluminum; piston crown; stainless steel（不锈钢）
注 在二冲程机中，活塞包含一个通常由铸铁制成的叫活塞裙的下部和一个由耐热钢制成的叫活塞头的上部。C
251.In order to keep the oil film on the cylinder liner during the running-in period, the piston rings are slightly rounded ____.
A.on both the external and internal top edges B.on both the external top and bottom edges C.on both the external and internal bottom edges D.on all the four edges
注 为了在气舡磨合期保证缸套上的油膜，活塞环外表面的上下边缘要轻轻打磨圆。B
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English of marine engineering (Operational Level)
252.*In order to control thermal stresses, some types of modern engines usa pistons with ____.
A. heavy wall and intensive cooling B.heavy wall and no cooling C. thin wall and no cooling D.thin wall and intensive cooling
业轮机工注 为了控制热应力，一些型号的柴油机活塞使用薄壁结构和强制冷却。D
程253.In order to improve the working conditions of the crosshead bearings, the bearing
pressure is made____and the peripheral speed is made____in later designs. 专 A.smaller; higher B.higher; smaller C.smaller; smaller D.higher; higher 注 为了改善十字头轴承的工作状况，在最近的设计中将轴承压力做得小一些，而轴承的圆周速度要做得大一些。A
254.The guide shoes are secured to the crosshead by means of ____.
A.through bolts(贯穿螺栓) B.end chock bolts C.side chock bolts D.top-bolts(六角头螺钉) 注 导致导板滑块用六角头螺钉固定到十字头上。D
255.Sealing between the crankcase and scavenging air boxes is achieved by means of ____.
A.the connecting rod stuffing boxes B.the piston rod stuffing boxes C.the sealing rings of piston D.the scraper rings of piston 注 曲轴箱和排气箱间密封是通过活塞杆填料函来获得的。B
256.*____ of different thickness are inserted between the shells to enable adjustment of the bearing clearances.
A.Screws B.Films C.Discs D. Shims(薄垫片) 注 不同厚度的调整垫片插入到轴瓦中以调整轴承间隙。D
257.Why are slow-speed diesel engines especially tall?
A.Because in this way the piston can be withdrawn downwards. B.Because the engine can occupy larger space.
C.Because the engine may have long strokes which improve engine efficiency. D.Because more maintenance is provided. 注 为什么低速柴油机特别高？因为他有长的行程提高主机效率。
258.*Large, slow-speed, two-stroke marine diesel engines offer the advantages of the following except ______.
A.burning poorer quality and cheaper B.providing large power C.being reversible
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