Gas Spring - Frequently Asked Questions

How a spring works?
A gas spring consists of a piston attached to a shaft moving within a sealed cylinder charged with nitrogen. The output forces are the result of the differential between the pressure in the cylinder and the atmospheric pressure outside the cylinder acting on the cross section of the piston/shaft. As the piston/shaft is compressed into the cylinder the internal pressure increases according to the volume of gas displaced by the rod. This increase in force is called the K-Factor.
Because they operate on simple pressure differentials, gas springs will perform as well in the vacuum of space as they do on land.

Force
Gas spring force is often designated as P1 which is the force measured 1 inch from full extension. Force is a function of the charge pressure in the cylinder acting on the cross section of the rod. The smaller the diameter of the piston/rod the lower the force at the same pressure. For example, a gas spring with a 9/16 (14mm) rod charged to 1000 psi will have a P1 force of 200 pounds while a spring with a 5/16 (8mm) rod charged to the same pressure will have a P1
force of 65 pounds. Compressed force is referred to as P2. This force is measured .2” (5mm) from full compression. The P2 force will always be greater than the P1 force.

K-Factor
K-factor is the ratio of the compressed force (P2) and the extended force (P1). As governed by Boyle’s Law, P2 force is always greater than the P1 force. During compression, the volume of the piston/shaft introduced in the cylinder displaces an equal volume of gas, increasing the pressure in the cylinder which increase the force of the spring.

What is a Gas Spring?
Ameritool Gas springs are self-contained, pneumatic devices capable of producing very large forces (5-1,200 lbs.) from a compacted piece. A gas spring consists of a piston attached to a shaft moving within a sealed cylinder charged with nitrogen. The piston has an orifice which allows gas pressure to pass through and act equally on both sides. It is the pressure acting on the shaft cross-sectional area which provides the springs its force.

The output forces are the result of the differential between the pressure in the cylinder and the atmospheric pressure outside the cylinder acting on the cross section of the piston/shaft. As the piston/shaft is compressed into the cylinder the internal pressure increases according to the volume of gas displaced by the rod. This increase in force is called K-Factor.

Because they operate on simple pressure differentials, gas springs will perform as well in the vacuum of space as they do on land.

What is the preferred mounting orientation of a gas spring?
In general, gas springs should be installed with the rod facing down to ensure the seals are lubricated and to reduce the permeation of nitrogen through the seal.