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LOW K Factor

These gas springs are most useful where a straignt lift is required (i.e.: TV monitors). The difference between the force when the gas spring is fully compressed and the force when it is fully extended will be very small, thus ensuring a near-constant hand force to be applied along its movement.

On a cabinet where the 50kg lid will have to be opened by hand over 130 degrees, we will try to use a low "K factor" gas spring in order to limit the maximum hand force to an acceptable level.
In this example, with a gas spring with K factor of 1.4, the hand force would reach 226 Newtons (22 kg) at 56 degrees opening, which in some cases would be unacceptable.
Using a combination gas spring which has a K factor of 1.1 the maximum hand force would be reduced down to 156 Newtons (15kg).

The horizontal scale represents the opening angle in degrees. 0 degrees is the closed position
The vertical scale represents the hand force in newtons

HIGH K Factor

In some cases it is in the interest of the user to have as much force as possible when the gas spring is compressed and a force as small as possible when the gas spring is extended.

A roof hatch is taken as an example here. There is almost no space available underneath the hatch to fit the gas spring, so the moment of the gas spring is small when the lid is closed. In order to help the user at the beginning of the lift this particular application requires a very strong gas spring.
On the other hand when the lid is fully open (at the point where the lid doesn't weigh anything) we want to limit the gas spring force so it is not too hard to close.
Using our standard size 10mm gas spring with 200mm stroke and a P1 force of 750 Newtons (K=1.3) we obtain the following curve.
On the same application, we are using a gas spring with 750 Newtons, therefore the hand force when the lid is open remains the same (71N). This time, because we have increased the K factor, the force of the gas spring is higher when compressed and the force required to lift the lid is therefore decreased (from 98N to 66N).

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