Newton (N) in Gas Struts — Lifting Force Definition (Replacement for LIFT-O-MAT)
The unit Newton (N) specifies the lifting force of a gas strut, which pushes a furniture front upwards and holds it open. The required force depends precisely on the weight and height of the flap. A correct Newton rating prevents the door from sagging or slamming open too forcefully.
What exactly is the lifting force in Newtons (N)?
In furniture construction, flap stays are used to open overhead cabinet fronts upwards. The core element of these systems is often a cylinder filled with nitrogen. The compressed gas filling creates constant pressure on the piston rod. The magnitude of this pressure is referred to as the lifting force and is measured in Newtons.
Technically speaking, the system functions like a precisely adjusted counterweight in a lift shaft: the force of the gas struts must exactly counterbalance the dead weight of the furniture front. If the N rating is too low, the flap falls shut again. If it is too high, the cabinet can only be closed with great effort, placing excessive strain on the hinges. Important: a gas strut is designed to open and hold, and must not be confused with a basic furniture damper used for a soft-close mechanism.
Replacement for LIFT-O-MAT: What to look out for during replacement
Defective dampers frequently need replacing after years of use. A well-known market standard is the LIFT-O-MAT series. When these lose pressure, the flap sags.
For a like-for-like replacement, two technical parameters are crucial:
- The lifting force (N): This value is usually printed directly onto the cylinder (for example "380 N" or "0380N"). The new strut must have the exact same rating.
- The dimensions: Crucial factors are the total length when extended (measured from hole centre to hole centre of the mountings) as well as the stroke (the pure travel distance of the piston rod in mm).
Typical ratings and standards for furniture fronts
Choosing the correct lifting force scales with the dimensions and material (e.g. MDF, solid wood, or chipboard) of the front. The following guide values are standard in practice:
- 50 N - 120 N: For very light, small flaps (e.g. narrow wall units above an extractor hood).
- 150 N - 250 N: For standard kitchen wall units of medium height.
- 300 N - 450 N: As gas struts for heavy flaps made from solid wood or featuring large glass fronts.
In addition to pure force, the components also vary visually to harmonise with the cabinet interior. Typical variants are gas struts black for dark decors or gas struts silver for classic white or grey carcases.
Calculating and selecting the correct gas strut
When designing a new cabinet, the required force must be calculated. The formula takes into account the weight of the flap (including the handle) and the height of the front.
A common rule of thumb for standard hinges is: weight of the flap in kg × 10 = required force in N. Example: A flap weighs 3.5 kg. 3.5 × 10 = 35 N. Because the centre of gravity of the flap lies further out, leverage comes into play, which is why in practice the calculated value is often multiplied by a factor (depending on the flap height).
In principle, it is advisable to always fit two flap stays per front (left and right). This prevents warping of the front panel and protects the concealed hinges through symmetrical load distribution. The calculated total force is then split between both struts (e.g. 2 × 250 N for a required total force of 500 N).
Related terms in furniture construction
- Stroke: The distance in mm that the piston rod can extend from the cylinder.
- Concealed hinge: Concealed cup hinge that attaches the flap to the carcase. The gas strut merely assists the opening movement.
- Mounting bracket: The metal fittings screwed to the carcase and front that carry the ball head to retain the strut.