Gaslift Technical Info

The Gaslift® spring consists of a cylinder, piston and rod assembly able to extend and contract telescopically.

The cylinder is filled with nitrogen gas at a very high pressure. It is this gas pressure which creates the lifting ability of the Gaslift® and the force exerted is proportional to the gas pressure.

A measured quantity of oil inside the Gaslift® lubricates the piston assembly and provides damping at the end of the extension movement. The damping imparts a more gentle action to the object being moved. Therefore, the Gaslift® should always be mounted with the rod in a downward position, when the door is fully opened.


Calculating the force required to hold the lid in the Open position.

Refer to the diagram:

F1 – Force exerted by Gaslift® in Fully Extended Condition

U – Upper Mounting PointL – Lower Mounting Point
P – Pivot Point
CG – Centre of Gravity
A – Horizontal Distance from CG to Pivot Point P
B – Perpendicular Distance from axis U-L to Pivot Point P
W – Weight/Mass of lid

If the position of the CG of the lid is not known, then a spring balance or similar can be used to measure the force required to hold the door open.

If the force is measured at the upper mounting point U this force plus 10 – 15% safety factor is the F1 required. If the force is measured at any other point, use the perpendicular distance from the pivot point P to the attachment point of the spring balance as A and the spring balance reading as W in the formula.

By changing the Gaslift® axis U - L the lid can be made to open automatically once the catch is released, or stay closed so that no catch is required. The calculated force is only enough to balance the mass – add more to keep the flap firmly in place. Work to low side of the calculated pressure at first because additional gas can be added, but pressure cannot be reduced.