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The following paper presents load analysis of propulsion engine during ship's speed acceleration. This process is carried out after manoeuvring in order to receive, as fast as possible, exploitation speeds of the ship, achieved during the voyage. The analysis concerns direct propulsion power system of low-speed engine of constant pitch propeller. Wrong steering process of engine load changes in temporary states, can cause engine overloading, as the result of its operation on the external limiting characteristic and can end up in engine seizure. Control of engine operation is carried on through selecting of adequate setting of rotational speed governor, which for specified external conditions can result in adequate position of fuel link and the choice of adequate fuel index arm dose. Equalization of the power delivered by the engine in given conditions of work with power required by the ship's propeller cooperating with the hull, will establish adequate rotational speed of the engine and finally the speed of the vessel. In order to speed up the sip's motion, there must occur an overflow of propeller thrust over the required thrust (resistance) and this, in turn, is connected with the necessity to ensure the engine power surplus over the power required for a given range of operation or in other words sailing speed. This article presents the working model of ship propelling system during speed acceleration and concerns mainly nonoverload running of the engine. The model described above has been verified during tests in real conditions at sea.

In engine, piston is an important element which is considered as the main working part. So it is important to be technical in selecting materials which are used to manufacture a piston. As it the main working part in the engine, automatically it will be subjected to more damage which depends upon the usage of the engine. Commonly the pistons are made up of aluminium alloys, because of its enormous strength and for other mechanical properties. In this project aluminium alloy is replaced with the composite of Aluminium (Lm25), Boron carbide (b4C) and Graphite (G). These hybrid composites are formed using stir casting method in three different ratios. All the three specimens with different ratios are subjected to tensile, hardness and wear tests. The observed values are tabulated and represented graphically. Those values are analysed and determined that the formed hybrid composite material is suitable for the manufacturing of piston rod.

The following article introduces determination method of displacement compressors basing on its work parameters, by means of dimensional analysis. Operation of displacement compressors as volumetric compressing devices, according to J. Girtler, has been treated as a new physical quantity of [J·s] dimension.Such operation can be interpreted as mechanical energy transfer, through working organ, to gas factor volume in working space of the compressor in a definite time.Operation of volumetric compressor in which energy transfer, takes place, can be an information carrier of its technical condition.It expresses transformation of energy delivered to the gas, being forced through, by the compressor. This quantity can be determined, on the basis of, algebraic diagram of dimensional analysis, constructed by S. Drobot.The above diagram allowed us to control correctness of inference rules, in relation to mathematics, used in numerical functions of volumetric compressors operation, fitted in installations.Constructional solutions of compressors depend on the kind of compressed factor, the way of cooling, size of compressor and on the kind of propulsion and destination of compressor.

The following article describes energetic states symptoms, included in correct and incorrect performance of crankpiston combustion engines systems. Special attention has been paid to accompanying processes of such performance, with regard to, heat generation effect in combustion chamber and friction in joined frictional movements. Combustion chamber is a moving space formed by connection of the piston through piston rings with the cylinder liner and the engine head. Heat generation process takes place above the piston, generated by burning of fuel. It causes an increase of gas pressure in the combustion space, which results in the movement of the piston tightened by the rings, followed by an increase of the space volume. In this way energy is emitted from fuel burning, influencing the elements of piston-conrod system in the form of heat and work. The ability of such thermodynamical system to convert energy into an effective one is limited. Internal energy of exhaust gases can be divided into the part which cannot be converted into work. The process of heat generation in engine cylinder is of irreversible character which results in the loss of energy. In piston combustion engines, work is performed by heat generated in cylinders. Energetic performance in piston-crank system results from internal exchange of exhaust gases in combustion chamber with the engine surroundings. Analysis of such energetic performances allows us to isolate symptoms of correct operation of piston con-rod combustion engine systems. Such symptoms include: exhaust gases temperature, temperature of piston surface, momentary values of torque and the speed of pressure increase during combustion. Piston-con-rod system is a component part of the engine. Evaluation of its performance allows to identify the present technical condition of the engine. Diagnostic advantages of some, above mentioned symptoms of piston-con-rod combustion engine operation, have been verified by means of adequate laboratory testing and during engine operation on the ship.