Pneumatic hydraulic retractable device

A pneumatic hydraulic retractable device comprising:

• a fluid pressure cylinder having a cylinder body and a plug seat disposed in the cylinder body and located at one end of the cylinder body;
• a piston rod movably disposed in the fluid pressure cylinder;
• a control valve set including a valve seat disposed at one end of the piston rod and forming an upper fluid chamber and a lower fluid chamber with the cylinder body therebetween, and a valve rod disposed in the valve seat and moved between a close position where the upper and lower fluid chambers do not communicate with each other and an open position where the upper and lower fluid chambers communicate with each other;
• and
• a pressure relief element disposed between the valve seat and the plug seat and penetrated by the piston rod and having a communication portion, one end of the pressure relief element and the piston rod forming a pressure relief gap therebetween communicating with the lower fluid chamber through the communication portion.