6．关联题
Passage 1
Valve drive mechanism
The valve drive mechanism commands the inlet and exhaust valves at the required timing.
第3题The valve drive mechanism consists of an inlet and exhaust cam follower凸轮随动件 (8) each suspended in 悬浮在…中a plunger of the tappet asmbly挺杆组件 (7), two tubular push rods空心的推杆 (4) with ball joints, two nodular cast iron 球墨铸铁rocker arms摇臂 (2) suspended in a rocker arm bearing bracket, two yokes吊梁(5) and a yoke guide pins导销. See Fig. 4-1.
The tappet rollers 推杆滚柱follow the cam profiles and transfer the movements through push rods to the rocker arms. 第4题The rocker arms operate the inlet and exhaust valves through yokes (5).
Lubrication for the rocker arms comes from the engine's condary oil supply manifold through
drillings in the cylinder head and rocker arm bracket.
第2题The tappet asmbly receives lubricating oil via channels in the engine block from the main supply manifold. For the roller and shaft, the oil is supplied through the guiding plunger.
第4题To compensate for heat expansion a clearance must exist between the rocker arm and yoke.第1题All adjustments have to be done on a cold engine only.
1. According to the Passage, the best time to adjust the valve clearance is _____.
A. before the engine is started B. when the engine is running
C. after the engine has just been stopped D. when something has gone wrong with the engine
注：根据文章来看，调节阀间隙的最好时间是在发动机启动之前。
2. The roller and the tappet asmbly are lubricated by means of_____.
A. the main lube system B. the condary oil system
C. the special pumping system D. the turbine oil system
注：滚轮和挺杆组件借助于主润滑系统润滑。
3. According to the Passage, the valve drive mechanism does not include_____.
A. tappet rollers B. push rods C. nodular cast iron D. yokes and guide pins
注：根据文章来看，阀驱动机构不包括球墨铸铁。（包括杆滚轮、顶杆、吊梁和导销）
4. To clo valves tightly, which clearance should be inspected according to the maintenance schedule?
A. The one between the cam and the tappet roller.
B. The one between the push rods and the ban joints.
C. The one between the rocker arms and the yoke
D. The one between two tubular push rods.
注：依据保养清单，要紧密的关闭阀件，应检查摇臂和吊梁之间的间隙。
AACC
Passage 2
Charge air cooler
The engine is equipped with a charge air cooler. The inrt type charge air cooler is mounted in a welded casing (air trunk). The trunk is bolted to the engine block.
第1题Standard is a two-stage cooler mounted. The first stage, through which the charge air flows, is cooled with water from the HT cooling system and cooks the charge air till approx. 90 ~ 100oC. The cond stage is supplied with water coming from the LT water system and cooks the charge air further till the required temperature of approx. 50oC. 第2题(B)By controlling the water flow through the LT cooler the charge air temperature can be kept constant at the required temperature.
The circulating coolant water should always be under positive pressure and should be as clean as possible. The operating air temperature should be maintained by controlling the coolant inlet temperature.
Whilst the engine is running the air and coolant temperatures and pressures at inlet and outlet should be checked and logged periodically. 第3题 Variations from normal indic
ate faults developing such as fouling of the film plates or obstruction of the water tubes.
第4题Check daily, during operation of the engine, the working of the telltale hole at the free end of the charge air receiver. The function of this hole is to inform the operator the prence of water in the charge air receiver. Under normal condition only compresd air should escape from this hole.
1. According to the Passage, the expression "HT" probably means_____.
A. HIGH TANK B. HIGH TEMPERATURE C. HEAT TRANSMISSION D. HEAT TRANSFER
注：根据文章来看, "HT"的意思是：high temperature，高温。
2. In order to maintain the change air temperature we should control_____.
A. the coolant inlet temperature coming from the first stage cooler
B. the coolant flow coming from the cond stage cooler
C. the coolant outlet temperature coming from the cond stage cooler
D. the coolant flow coming from the flint stage cooler
注：为维持增压空气的温度，我们应控制来自第二级冷却器的冷却剂流量。
3. The charge air temperature departing from normal may indicate that_____.
A. condensate can be formed
B. only compresd air should escape from the telltale
C. the film plates are becoming dirty or the water tubes are blocked by scale
D. cooling water may have been carried into the cylinders
注：增压空气温度偏离正常表明镀膜变脏或水管被水垢堵塞。
4. The function of the telltale hole is to_____.
