4 stroke

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Measure Indicated Power in Diesel Engine with Indicator Diagram

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The burning of fuel in an engine cylinder (2 stroke or 4 stroke diesel engine) will result in the production of power at an output shaft, some of the power produced in the cylinder will be used to drive the rotating masses of the engine. Typical indicator diagram for a 2 stroke engine is shown in figure below. The area within the diagram represents the work done within the cylinder in one cycle. The area can be measured by an instrument known as 'Planimeter' or by the use of the mid ordinates rule. [On modern engines this diagram can be continuously taken by employing two transducers, one pressure transducer in the combustion space and other transducer on the shaft. Through the computer we can thus get on line indicated diagram and power of all cylinders.] The area is then divided by the length of the diagram in order to obtain mean height. This mean height, when multiplied by the spring scale of the indicator mechanism, gives the indicated mean effective pressures for the cyli...
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Crankcase relief valve testing

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FLAME ARRESTORS AND SHIELDING The intention of the requirement to shield the valve discharge was to reduce the possible danger to personnel from flame emission. However explosion testing has shown that whilst a flame arrestor will work satisfactorily when shielding is not fitted, when shielding is fitted, the energy from the discharge is focussed in one direction, and there will be an emission of flames during an explosion. The fitting of shielding also reduces the effective outflow area of a valve. Since July 2002 it has been a Lloyds Register rule requirement to fit flame arrestors and to test the relief valve with any proposed shielding to be fitted to the valve when installed on the engine. A test procedure for new crankcase relief valves has been developed over the past four years by MAN B&W, The Physical Test Institute in the Czech Republic , Hoerbiger, and various classification socie...
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Crosshead

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The Crosshead The crosshead pin connects the piston rod to the connecting rod. On either side of the crosshead pin are mounted the crosshead slippers. The slippers run up and down in the crosshead guides as the piston and rod are reciprocating and prevent the top of the connecting rod from moving sideways. The crosshead pin sits in the crosshead bearing which is either a forked type (shown left), where the bearing housings are mounted on the top of the connecting rod either side of the piston rod, or of the continuous type (shown above and below), where the bearing housing is formed by the top of the connecting rod. On the forked type, the piston rod passes through a hole in the crosshead pin and is secured by a nut. On the continuous type, the piston rod has a foot which is bolted onto the top of the crosshead pin. Modern engines are fitted with the continuous type of bearing. The crosshead bearing is difficult to lubricate effectively. Because the top of the connecting rod s...
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