In a variety of reciprocating piston compressors, the most typical, the most widely used is a variety of crankshaft-driven reciprocating piston compressors. Single-acting reciprocating piston air compressors without crosshead. The rotating crankshaft rotates the piston through the connecting rod to make reciprocating linear movement along the inner wall of the cylinder. When the piston moves downward, the working volume between the piston end and the cylinder is increased to form a vacuum, when the air filter is pushed through the suction valve and sucked into the cylinder. When the piston is in reverse motion, the suction valve closes, the gas enclosed in the cylinder is compressed, and the pressure increases as the volume decreases. When the pressure of the compressed gas is slightly higher than the air pressure in the exhaust pipe and the resistance of the exhaust valve spring, the gas pushes the exhaust valve into the vent pipe. Used to control the gas inhalation and exhaust cylinder parts called the valve, it in the pressure difference and spring force under the action of their own headstock, so called the automatic action valve. The most commonly used valve structure. Due to structural reasons, in the end of the exhaust gas in the cylinder there is still part of the air, the air cylinder in the space to hold the remainder of the volume. At the beginning of the piston downward movement, the volume of air in the cylinder expands, until the pressure inside the cylinder is slightly lower than the air pressure inside the suction tube, the suction valve opens, and the cylinder absorbs fresh air from the suction tube. 4 processes of suction, compression, venting and expansion in the cylinder form a cycle.
When the air is compressed in the cylinder, the temperature of air and cylinder is continuously increased. In order to keep the lubrication and friction parts of the cylinder working properly, a cooling facility (water jacket or heat sink) with water or air is arranged on the outer part of the cylinder to prevent the air from compressing at the end of the permissible value.