Changzhou Colewell Machinery Co., Ltd.

As the piston rod is introduced into the cylinder (compression stroke), the internal gas volume decreases resulting in a proportional increase in pressure (Boyle’s Law). Consequently, the force of a gas spring is higher when the rod is compressed (see Figure 1).

The difference between the forces seen at the two extreme rod positions- named P1-force and P2-force respectively- is an important gas spring characteristic and called K-factor (IGS) or gas spring progression. When compared to mechanical springs, gas springs can achieve very low K-Factors, typically ranging from 1.05 to 1.8 (or %-80% progression). Unlike coil springs, gas springs are pre-loaded (pressurized) at the required P1-force which is available immediately.

For this reason, P1 force must be taken in account when calculating the force of a gas spring at a given position:

Where F is the force of a gas spring, k is the spring constant expressed in N/mm (force change per unit of compression) and X is the deflection distance in mm.