1. piston stop point and stroke: a) Baotou North Mercedes Benz parts piston in the cylinder for reciprocating movement of two extreme positions called the "stop point". The most distant position of the piston from the center of the crankshaft is the top dead center. The location of the center from the crankshaft is called the bottom dead center. B) The distance between the top and bottom stops is called the piston stroke. The crankshaft turns half circle, which means that the piston moves one stroke. 2. displacement a) Baotou North Benz parts piston reciprocating motion in the cylinder, the volume of the cylinder is constantly changing. When the piston is located at the top stop point, the space formed between the top of the piston and the inner surface of the cylinder cover of the northern Mercedes Benz parts of Baotou is called the combustion chamber. The volume of this space is called the volume of the combustor. B) the space volume that the piston moves from the stop point to the lower stop point is called the cylinder displacement. If the engine has several cylinders, the sum of all the working volumes of the cylinder is called the engine displacement. C) when the piston is located at the bottom dead center, the volume of all cylinders on the top of the piston is called the total volume of the cylinder. 3. compression ratio a) the ratio of the total volume of the cylinder to the volume of the combustion chamber is called the compression ratio. The compression ratio indicates the degree of compression of the gas in the cylinder when the piston moves from the bottom dead center to the TDC. B) the greater the compression ratio, the greater the compression of gas in the cylinder, the higher the pressure and temperature of the gas at the end of the compression end, the greater the power, but the higher the compression ratio, the detonation is easy to occur. C) Compression ratio is an important structural parameter of the engine. Due to the different fuel properties, different types of engines have different requirements for compression ratio. The larger compression ratio of diesel engines is usually between 12-29, while the compression of gasoline engines is relatively small, which is between 6-11. High compression gasoline can be used to increase compression ratio partially.