How gas springs work ?

A gas spring is basically a system consisting of a pressure tube, rod and piston. The energy for the spring is provided by gas at high pressure and the whole system is self contained and sealed against loss.

The force F exerted by the spring arises as a result of the out of balance forces acting on the piston which can be calculated as follow:

The sum of all forces equal zero: F + [P * (A - a)] - P * A = 0

which can be reduced to: F = P * a


F = Expressed in Newtons (N)

P = Gas pressure in Pascals (Pa) (Newtons per square metre)

a = Rod cross section in square metres (m^2)

A = Piston cross section in square metres (m^2)

Compression ratio - "K Factor"

Because the gas spring is a closed system, as the rod is pushed into its body, the gas has nowhere to go and therefore the gas in the spring compresses and its pressure increases. If P1 is the force of a fully extended gas spring and P2 the force of the same spring when compressed then:

K = P2 / P1


P1 = The static force of a fully extended gas spring

P2 = The static force of the same gas spring when fully compressed