Replacing Gas Struts & LIFT-O-MAT: Finding the Right Replacement by Newton Rating (N)

May 26, 2026

A gas strut is a hydropneumatic component that uses a pressurised gas mixture to enable the controlled opening, holding open, and damped closing of furniture flaps.

Replacing a defective damper on a wall unit or chest is a standard maintenance task in cabinet making. When the flap no longer stays up on its own or drops unhindered, the component has lost its internal pressure. For a professional replacement, it is essential to select the spare part strictly according to the physical specifications of the original. Visual similarity is not enough. The decisive parameters are the extension force, the working stroke, and the overall length.

This guide explains the technical function, how to correctly determine the required force, and the steps for safe installation.

Technical Fundamentals: How Does a Gas Strut Work?

A classic gas strut consists of a sealed cylinder (also known as a pressure tube) and a moving piston rod. Inside the cylinder is nitrogen gas under high pressure, as well as a small amount of oil.

The oil serves two purposes: it lubricates the seals to prevent gas leakage, and it provides end-position damping. The compressed nitrogen filling acts like an invisible cushion that softly cushions the weight of the flap when closing and provides the necessary lifting force when opening. As the piston rod retracts into the cylinder, the internal volume decreases, causing the gas pressure to rise proportionally. When opening the flap, the gas expands and pushes the piston back out.

Distinction from Other Fittings

In trade terminology, terms are often mixed up, which makes a clear technical distinction necessary. A gas strut actively generates force to lift and hold a weight. It must not be confused with pure stopper systems. Buffers & dampers (soft-close cylinders) generate no pushing force of their own. They serve exclusively to absorb the kinetic energy of a closing door or drawer and delay the impact.

Likewise, the term LIFT-O-MAT is strictly speaking a registered brand name of the manufacturer Stabilus, which has become established in furniture construction as a generic term (deonym) for gas struts. Technically, these models are standard gas struts for lifting and lowering mechanisms.

The Most Important Criterion: Determining the Newton Rating (N)

The force of a gas strut is specified in Newtons (N). This value defines the extension force of the piston rod and must be matched precisely to the weight and leverage of the respective furniture flap.

Reading the Old Value

For a direct replacement, the easiest method is to read the value from the defective component. There is usually a print on the cylinder. Look for a number ending in "N". Typical ratings in furniture construction are:

50 N
80 N
100 N
120 N
150 N
200 N
250 N
320 N
380 N

The number is often integrated into a longer serial number, for example "0824 0150N". In this case, the extension force is exactly 150 N.

Calculating the Required Force Yourself

If the print on the old cylinder is illegible or you are building a piece of furniture from scratch, the required force must be calculated. As a rough rule of thumb: 10 N corresponds to a lifting force of approximately 1 kg. However, because two struts are always installed on a flap (to prevent warping at the hinges), the required force is divided between them.

Furthermore, the lever arm plays a decisive role. A deep flap requires stronger struts than a shallow flap of the same weight. For an exact calculation, you must determine the weight of the flap.

The weight is calculated from the volume of the flap (height x width x material thickness in metres) multiplied by the specific density of the material:

Chipboard: approx. 650 kg/m³
MDF: approx. 750 kg/m³
Solid wood (e.g. oak): approx. 800 kg/m³

A calculation example for an MDF flap measuring 60 cm in width, 40 cm in height, and 19 mm in thickness: 0.6 m x 0.4 m x 0.019 m = 0.00456 m³ 0.00456 m³ x 750 kg/m³ = 3.42 kg.

The flap weighs around 3.4 kg. Add to this the weight of the handle (e.g. 0.2 kg). The total weight is therefore 3.6 kg. For this weight, a holding force of around 36 N is required. However, because the mounting point of the strut is not at the bottom edge of the flap but closer to the hinge, the law of levers applies. In practice, the flap weight is multiplied by a factor derived from the distance between the hinge and the mounting point. For standard kitchen flaps of this size, two struts of 50 N or 60 N each are typically used.

For solid wood flaps or very large fronts above the fridge, standard values are not sufficient. Special gas struts for heavy flaps are used here, reaching values from 320 N to over 400 N.

What Happens with an Incorrect Newton Rating?

Choosing the correct value allows for no major tolerances.

Rating too low: The flap does not open fully or drops shut immediately. The struts cannot support the weight.
Rating too high: The flap can only be closed with great effort. Worse still: the permanent excess pressure in the closed state strains the concealed hinges. In the long term, this causes the screws to tear out of the chipboard or bends the hinges.

Taking Measurements: Overall Length and Stroke

In addition to force, the physical dimensions of the replacement part must be compatible with the existing cabinet carcass and mounting points. There are two critical length dimensions:

Overall length (extended): This dimension is measured in the fully opened state. Important: measurement is not taken from edge to edge, but from the centre of the ball socket (the mounting hole) to the centre of the opposite ball socket. Common lengths in furniture construction range between 245 mm and 270 mm. A deviation of 2 mm to 3 mm is usually unproblematic, as the mounting plates on the carcass often feature slotted holes.
Stroke: The stroke refers to the distance the piston rod can retract into the cylinder (the difference between extended and retracted length). A typical stroke for furniture flaps is 90 mm. If the stroke is too short, the flap cannot open fully to 90° or 110°.

Aesthetics and Integration into the Carcass

In modern furniture, the interior view of the carcass is an important design element. The fittings should blend harmoniously into the decor. The cylinders are therefore available in various surface finishes.

For white or light interiors (e.g. Sonoma Oak decor), silver gas struts are frequently used. They have a technical and discreet appearance. For dark carcass colours, industrial designs, or anthracite kitchen cabinets, black gas struts are ideal. Technically, there are no differences between the colours; stroke, force, and mounting points are standardised.

Typical Applications for Gas Struts

The areas of application for these components go far beyond the classic wall unit. Sizing and mounting positions vary depending on the type of furniture.

Kitchen wall units: The classic application. The struts keep the flap open while the user removes crockery. Especially in cabinets integrating a dish rack for wall units, a reliable holding function under damp conditions and daily use is essential.
Chests and storage benches: Here, the struts are mounted vertically. They prevent the heavy wooden lid from slamming uncontrolled onto the carcass when closing, which represents a significant risk of finger injury.
Wardrobes: In tall wardrobe systems, special lever mechanisms are used. A wardrobe lift uses integrated gas struts to swing a fully loaded clothes rail down from the upper wardrobe area in a controlled manner and support swinging it back up.
Office furniture and cable management: On solid desks, flaps that provide access to cabling are often fitted with small gas struts (e.g. 50 N) to ensure smooth opening.
Microwave and oven housings: Flaps above built-in appliances require heat-resistant fittings that deliver consistent pressure despite temperature fluctuations in the kitchen.

For all these applications, struts form the core of flap fittings. They always work in conjunction with the actual hinges (usually concealed cup hinges), which guide the door.

Installation Guide: Replacing Gas Struts Professionally

Replacing a gas strut is a straightforward task that can be carried out by a DIYer in a few minutes. Removing the entire flap is not necessary.

Required Tools

Small flat-blade screwdriver
Cross-head screwdriver (PZ or PH drive) to check the mounting plates
If necessary, an assistant to hold the flap

Step 1: Secure the Flap

Open the furniture flap fully. Because you will remove one of the struts in the next step, the flap will no longer be able to support its own weight. Have a second person support the flap or insert a temporary prop (e.g. a wooden lath).

Step 2: Release the Retaining Spring

Most gas struts are equipped with ball sockets at the ends that clip onto a ball stud on the mounting plate. To prevent them from popping off, a small metal retaining spring (a U-shaped metal clip) sits on the ball socket. Carefully slide the flat-blade screwdriver under this clip and lever it slightly upwards. Raising the clip by 2 mm to 3 mm is usually sufficient. It does not need to be removed completely.

Step 3: Pull Off the Old Strut

Once the clip is released, you can pull the ball socket sideways off the ball stud with light pressure. Repeat this process at the other end of the strut.

Step 4: Check Mounting Plates

Before fitting the new replacement part, inspect the round mounting plates screwed onto the wood. Check whether the wood screws are still tight in the material. If a screw has worked loose, tighten it with the appropriate cross-head screwdriver. If the drill hole in the chipboard is already stripped, fill it with some wood glue and a matchstick before driving the screw back in to create fresh grip.

Step 5: Clip On the New Strut

Fitting the new strut requires no tools. Simply push the ball sockets of the new component firmly onto the ball studs of the mounting plates with your thumb until they audibly click into place. The retaining spring does not need to be lifted beforehand; it spreads automatically when pressed on and encloses the ball stud.

Important Technical Note on Orientation

Pay strict attention to the installation orientation. When the flap is closed, a gas strut must be positioned so that the thin piston rod points downwards and the thick cylinder points upwards. Why is this important? Gravity causes the aforementioned oil inside the cylinder to collect at the lowest point. If the piston rod points downwards, the seal remains permanently immersed in the oil bath. This keeps the seal supple and prevents the highly pressurised nitrogen gas from escaping. If the strut is mounted upside down, the seal dries out and the component loses its function within a few months.

FAQ – Frequently Asked Questions About Gas Struts

Can a defective gas strut be repaired or refilled? No. Gas struts for furniture construction are sealed, maintenance-free systems. The nitrogen is under high pressure (often over 100 bar). Once the gas has escaped due to seal wear, the entire component must be replaced. Refilling is neither technically feasible nor safe at these dimensions.

Do both struts on a flap always need to be replaced at the same time? Yes, this is strongly recommended. Even if only one strut seems defective, the second strut has typically reached a similar lifespan and has already lost force. Replacing only one side results in asymmetric force. The new, strong strut pushes unevenly against the flap, leading to distortion of the front and extreme wear on the hinges on the opposite side.

Why does the gas strut squeak or creak when opening? Noise usually occurs when internal lubrication diminishes or the ball studs run dry. A drop of silicone spray on the outer ball stud can help. Important: never spray oil, grease, or WD-40 onto the shiny piston rod! Dirt particles would adhere to the oil and destroy the delicate seal inside the cylinder upon retraction.

How do I clean the piston rod properly? The piston rod should only be wiped with a dry, lint-free cloth. Chemical cleaners or abrasive sponges damage the micro-fine surface coating, which inevitably leads to gas loss.

Can I replace a 150 N strut with a 200 N strut to make the flap open faster? That is a common installation mistake. The force must match the flap weight precisely. A strut that is too strong (e.g. 200 N instead of 150 N) pulls the flap upwards aggressively when opening, which can rip the fixing screws out of the carcass. Furthermore, closing the flap becomes very strenuous. Always stick to the Newton rating originally calculated by the furniture manufacturer.

Is there a difference between gas struts for wooden fronts and those for aluminium frames? The cylinder and mechanism are identical. The difference lies exclusively in the supplied mounting plates. Aluminium frame profiles are very narrow (usually 20 mm). Special, narrow mounting plates secured with machine screws in the metal profile are required for them, whereas wider plates with standard chipboard screws are used for wooden fronts.

How long does a gas strut last in furniture construction? Lifespan depends on frequency of use. High-quality struts are designed for around 40,000 to 50,000 movement cycles (opening and closing). In an average kitchen, this corresponds to smooth operation for about 5 to 10 years. Severe temperature fluctuations (e.g. directly above an oven) can shorten the lifespan of the seals.

Related Categories and Guides

If you are comprehensively repairing or building your furniture, you will find matching components and complementary systems in the following categories:

Gas Struts – Overview of all standard forces and lengths.
LIFT-O-MAT – Specific replacement parts and compatible cylinders.
Flap Fittings – Complete mechanisms for bi-fold and lift-up flaps.
Gas Struts for Heavy Flaps – For solid fronts and high weights.
Concealed Hinges / Cabinet Hinges with Soft Close – Matching hinges to guide the flap.
Buffers & Dampers – For silent closing of standard hinged doors.