Working principle of the gas spring 

Gas springs create weight balance and thus counteract the weight of a lid. When opening a flap, the manual force is supported by the gas spring. The gas spring is a self-contained and maintenance-free element. It consists of a pressure pipe and a piston rod with piston. 
There is also a seal on the guide of the piston rod to prevent possible gas loss. The gas spring is filled with compressed gas - nitrogen - which is used to provide the spring force. It also contains a small amount of hydraulic oil for end position damping and lubrication of the gas springs. The amount of oil influences the internal pressure of the gas spring. The more oil, the less room for nitrogen. This pressure acts on the cross-sectional area of the piston rod, which results in the extension force of the gas pressure springs. When unloaded, the piston rod is always extended. 
By pushing in the piston rod, the volume in the cylinder decreases and the gas is compressed. This results in an increase in force (progression) of the gas spring. This depends on the diameter of the piston rod and the volume of the cylinder. Gas springs serve as a lifting or tension element to support movements. Our standard series is characterized by very good performance data, a long service life and optimized corrosion protection.