Posted to News on 7th Nov 2006, 00:00
New approach for tension springs
Industrial Gas Springs has launched a new range of tension springs. Fixed force units which typically have a rod and an inner and outer cylinder to achieve the desired axial force, they are not equipped with a release valve or damping. The fully pressurised cylinder design provides a tension force by means of an inner body construction which works in reverse to that of a typical compression gas spring.
The P1 force of a tension spring is measured at 5mm from its fully closed position. This is nominally the spring's normal 'at rest' condition under no load. A tension spring still has a compression ratio or K factor, this being the ratio between the P1 and P2 forces (P2/P1). The P2 force for a tension spring is defined as the force of the spring, measured 5mm from full extension.
The new range of tension springs are typically supplied with a K factor of 1.3 to 1.6 with a force range of 100-1500N, although up to 3500N variants will be available. The inner body is made from stainless steel to provide superior corrosion resistance and longer life. The range features end fittings (eye, ball joint, clevis) with common threads at both ends; ball joints are recommended to prevent side load forces being exerted on the unit during operation.
A minimum of 3mm of rod is exposed outside the tension gas spring to clearly show which the rod end is, to enable installation in 'rod down' configuration. This is necessary to keep the main seal lubricated by the oil within the spring to prevent it from drying out. The standard tension gas spring range comprises sizes 6-14 rod diameter and force range of 100-3500N. The 'pulling' action of the tension springs, as opposed to 'pushing' with a compression spring, makes them suitable for lid-type applications where access is restricted such as vehicle ramps and food processing equipment.
