Hermetic reciprocating compressors welded, the engine (reciprocating type compressor) placed in a sealed body is in a structure where service services such as maintenance and repair cannot be provided. The mechanical system in this body, a piston that makes a linear reciprocating motion in the cylinder, is shown in Picture 2.2. In obtaining this linear motion, a crank and connecting rod that converts circular motion to linear motion are used (see Picture 2.3).
The application conditions of reciprocating compressors are suitable for refrigerants with a low cylinder volume requirement corresponding to the unit refrigerant cooling capacity, but with a large suction/discharge pressure difference.

With the linear movement of the piston in the cylinder, there are valves that are activated during suction and discharge. These valves are called suction valve and discharge valve, taking the same name due to the location they work in. In Figure 2.4 and Figure 2.5, the discharge and suction valves are shown on the valve plate. The reciprocating compressors we mentioned have more mechanically working parts, which also increases the probability of failure.
In fully closed hermetic type reciprocating compressors, vertical axis crankshaft and engine and horizontal axis cylinder arrangement are very often applied. Due to the nature of fully hermetic reciprocating compressors, the suction steam passes through the motor windings before being taken into the cylinder or cylinders. This helps both to remove some of the heat from the motor windings and to evaporate any liquid refrigerant that may have entered the compressor.