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The fixed support of the receiver of double spring plate type is( ) ① modified from that of the receiver of single spring plate type; ② to reduce the local deformation of the receiver; ③ to produce less natural frequency of the support

After ensuring that the "nip" is correct the bearing clearance should be checked. The bearing cup and its associated half shells are removed leaving the other half in position. Two pieces of pure lead wire are placed across the journal at positions one-third and two-thirds along its length. The cap and shell are replaced and tightened up until the "nip" is zero. The cap and shell are then removed and the thickness of the lead wire measured by a micrometer. It is important to use only pure lead, which is very soft, and to choose a thickness of wire, which is greater than the normal allowable clearances but not greater than twice this amount. The clearance should be within the manufacture's limits. As a guide these will be approximately 0.1 to 0.2 mm for white metal bearings and approximately 0.25 to 0.4 mm for copper-lead or tin-aluminum bearings with crankshaft journal diameters in the range from about 200 to 400 mm.【缺少答案，请补充】

The lead wire should be put on the upper surface of the journal( )

Which of the following statements is TRUE?

According to the passage, the thickness of the lead wire should be measured

According to the passage, the clearance for white metal bearing should be( )

The Wartsila 50DF applies the sophisticated dual-fuel technology incorporated in the reliable and well tried Wartsila 46 HFO engine. The Wartsila 50DF is designed to provide high output with fuel flexibility, low emission rates, high efficiency and high reliability. The engine functions are controlled by an advanced automation system that allows optimum running conditions to be set independent of the ambient conditions or fuel. Both the gas admission and pilot fuel injection are electronically controlled. This ensures that the correct air-fuel ratio can be set for each cylinder individually and that the minimum amount of pilot fuel can be injected while ensuring safe and stable combustion. All parameters are controlled automatically during operation. The Wartsila 50DF is designed to meet customer demands for a safe and fuel-flexible engine, running both on gas and on liquid fuel. The 50DF, like all Wartsila engines, has a simple and straightforward design. Its piping and external connections have been minimized, the safety margins are ample, maintenance is easy and rapid, and the electronic safety protection system is a built-in feature. The individually and electronically controlled valves ensure that all cylinders say within the operating window, avoiding knocking and misfiring. This eliminates unnecessary load reductions and shutdowns. The Wartsila 50DF is designed to give the same output whether it is running on natural gas or on LFO/HFO. For the Wartsila 50DF operating on gas, NOx and CO2 emissions are substantially lower than for an HFO engine. The engine is optimized for NOx emissions of 500 mg/Nm3 at5% O2, dry and fulfils the German TA-luft standard for operation on natural gas. This corresponds to 2 g/kWh of NOx. Back-up fuel: 970 ppm vol at 15% O2, dry, for World Bank NOx or below 12.91 g/kWh following the marine requirements.【缺少答案，请补充】

Which of the following can NOT be used on the Wartsila 50DF?

Which of the following is NOT the main function of an advanced automation system for the Wartsila 50DF?

For the Wartsila 46, what is the content of NOx emissions at 5% O2?

The gas admission and pilot fuel injection of the Wartsila 50DF are controlled by( )

The bedplate, which in most cases is of the welded design, is bolted to the seating which forms a part of the double bottom of the ship. It is secured in the transverse direction by means of bolts known as side -chock bolts and in longitudinal direction by means of end-chock bolts. The crankshaft rests in bearings built into cross girders of the bedplate. These bearings, known as main bearings, each consists of two shells which are supported in housings machined in the bedplate and secured by means of studs and bearing caps. The thrust block or thrust bearing, located at the aft end of the engine, may be integral with, or separate from the bedplate. On the flat upper surface of the bedplate are arranged a number of A-shaped frames or entablatures which may be manufactured of cast iron or fabricated steel. The frames are mounted on and bolted to the bedplate cross girders. At the top of the A-frames there is a strong cast iron frame called the scavenging air box, which is built of a number of sections provided with vertical flanges enabling them to be bolted together to form a block for 1-3 cylinders in front of the chain transmission, and a block with 4-6 cylinders aft of the chain transmission. The chain transmission, forming the connection between the crankshaft and the camshaft, is enclosed in a cast iron casing known as the chain drive casing.【缺少答案，请补充】

The main bearings are ( )

The entablatures are( )

The scavenging air box is( )

The chain transmission is( )

Lubricating oil from the compressor will pass along the air lines and deposit on them. In the event of a cylinder air starting valve leaking, hot gases would pass into the air pipes and ignite the lubricating oil. If starting air is supplied to the engine this would further feed the fire and could lead to an explosion in the pipe lines. In order to prevent such an occurrence, cylinder starting valves should be properly maintained and the pipelines regularly drained. Also oil discharged from compressors should be kept to a minimum, by careful maintenance. In an attempt to reduce the effects of an explosion, flame traps , relief valves and bursting caps or discs are fitted in the pipelines. In addition an isolating non-return valve ( the automatic valve) is fitted to the system, which prevents further compressed air by the engine into the system. The loss of cooling water from an air compressor could lead to an overheated air discharge and possibly an explosion in the pipe lines leading to the air reservoir. A high temperature alarm or a fusible plug which will melt is used to guard against this possibility.【缺少答案，请补充】

In which combination of the following situations could an explosion occur in the air pipelines? ①Lubricating oil deposits on the air lines; ②Hot gases ignite the lubricating oil; ③Starting air is supplied to the engine.

An isolating non-return valve is a non-return valve which( )

The purpose of the non-return valve fitted to the air system is( )