It is called a liquid stroke at the free inlet of the liquid in the compressor cylinder.
When this happens, the mass of the refrigerant and the oil inside the cylinder are much larger than that allowed for the flow in the orifices of the discharge valves, causing some of the internal components of the compressor (connecting rod, piston, valves, etc.) .
To reduce the effects of this situation, it is used to secure the discharge valve assembly by a spring that compresses from a force, thereby allowing the refrigerant and oil to pass freely.
