The Definitive Guide On How To Measure Gas Struts For Precise Replacements
Accurately measuring gas struts requires capturing the extended length from the center of one mounting point to the center of the other, alongside the stroke length and force rating in Newtons. Selecting a replacement based on these precise dimensions ensures structural compatibility and prevents mechanical failure or safety hazards during operation.
Pre-Procedure Requirements and Essential Measurement Tools
Before attempting to source a replacement gas strut, you must ensure the existing unit is fully extended and safely stabilized. Measuring a strut that is partially compressed or under load will lead to incorrect sizing and potential damage to your equipment. Gas struts are high-pressure cylinders filled with nitrogen gas; attempting to disassemble or force them open manually is dangerous.
- Essential Tools:
- Digital or analog calipers: Provide the highest degree of accuracy for measuring rod and tube diameters.
- Measuring tape or rigid ruler: Required for measuring extended center-to-center length.
- Notepad and pen: To record force (Newtons) and dimensional data immediately.
- Soft-bristle brush or microfiber cloth: To clean the strut casing to reveal stamped manufacturer specifications.
- Prerequisite Knowledge:
- Understanding of the Newton (N) unit, which defines the force the strut exerts.
- Familiarity with end-fitting types, such as ball sockets, eyelets, or clevis mounts.
- Estimated Duration: 15 to 20 minutes for a standard multi-point measurement process.
The Technical Workflow for Accurate Gas Strut Sizing
Step 1: Establish the Extended Length
The most critical dimension is the extended length, measured as the center-to-center distance between the mounting points. Place your tape measure or ruler exactly in the center of the ball stud or mounting bolt on one end and extend it to the center of the mounting point on the opposite end. Ensure the strut is at its maximum natural extension. If the strut is worn and will not stay extended, you may need a second person to hold the lid or hatch in the fully open position while you measure.
Pro-Tip: Always measure in millimeters for global standard compatibility, as most manufacturers list specifications in metric units.
Step 2: Determine the Stroke Length
The stroke is the total distance the rod travels as it moves from its fully extended position to its fully compressed position. To calculate this, measure the length of the exposed metal rod when the strut is fully extended. Subtract approximately 10 to 15 millimeters from this measurement to account for the internal stop and the rod guide depth. This total travel distance determines how far your application will open.
Step 3: Identify the Force Rating
The force rating, measured in Newtons (N) or occasionally in pounds-force (lbs), is usually printed on the side of the cylinder casing. Look for a label or laser etching that specifies the force, such as 300N or 50lbs. If the label is faded or missing, you will need to determine the weight of the hatch or lid. Weigh the lid, and divide by the number of struts used to estimate the required force per strut, factoring in the leverage ratio of your specific mounting points.
Step 4: Verify End-Fitting Compatibility
The mounting hardware dictates how the strut attaches to your application. Common fittings include 10mm ball sockets, threaded studs, or eyelets. Inspect the connection point on your frame to see if it utilizes a ball stud or a through-bolt. When ordering replacements, ensure the new strut includes the correct end-fittings, or confirm that your existing fittings can be removed and threaded onto the new unit.
Step 5: Measure the Cylinder and Rod Diameters
Measure the outer diameter of both the main body (the cylinder) and the rod (the thinner shaft). Standard industry sizes for the rod often include 6mm, 8mm, or 10mm, while the cylinder is typically 15mm, 18mm, or 22mm. Matching these dimensions is vital to ensure the new strut fits within the existing mounting clearances and provides the necessary dampening performance.
ARANA Gas Struts Instruction Manual - 23 inch 200LB
Standard Technical Parameters for Gas Strut Specifications
| Parameter | Metric / Standard Unit | Critical Function |
|---|---|---|
| Extended Length | Millimeters (mm) | Defines maximum opening arc |
| Stroke Length | Millimeters (mm) | Defines total travel distance |
| Force Rating | Newtons (N) | Manages weight load support |
| Rod Diameter | Millimeters (mm) | Dictates structural rigidity |
| Cylinder Diameter | Millimeters (mm) | Determines force capacity/size |
| End Fitting | Type (Ball/Eye/Clevis) | Defines mounting interface |
Common Failure Scenarios and Field Corrections
- Failure Scenario: Strut fails to hold the hatch open.
- Root Cause: Loss of nitrogen pressure due to seal wear.
- Actionable Fix: Replace the strut entirely; gas struts are sealed systems and cannot be recharged or repaired in the field.
- Failure Scenario: The hatch slams shut immediately.
- Root Cause: Insufficient force rating or incorrect geometry.
- Actionable Fix: Verify the force (N) matches the lid weight and ensure the mounting points provide sufficient mechanical leverage.
- Failure Scenario: The lid does not close completely.
- Root Cause: Replacement strut has a stroke length that is too long (compressed length is too large).
- Actionable Fix: Measure the compressed length of the original strut and ensure the replacement matches or is shorter than this dimension to allow for full closure.
Frequently Asked Questions
Can I use a gas strut with a higher Newton rating than the original?
Using a strut with a slightly higher force rating can help if the hatch has become heavier or if you need more assistance, but exceeding the original force significantly can put excessive stress on the mounting brackets and hinges. It is recommended to stay within 10% of the manufacturer’s original force specification unless you have modified the weight of the application.
Why is my new strut labeled with a different measurement than my old one?
Manufacturers sometimes use different nomenclature for the same physical size, or your old strut may have been a custom OEM part with non-standard dimensions. Always prioritize the center-to-center extended length and the force rating (N) over any other branding or part numbers.
Do I need to replace gas struts in pairs?
Yes, it is best practice to replace gas struts in pairs, even if only one has failed. If one strut is new and one is old, the uneven force distribution can cause the hatch to twist or bind, leading to premature failure of the new strut or damage to the mounting hardware.
How do I safely release the old gas strut?
Most struts are held in place by small metal clips on the end fittings. Use a flat-head screwdriver to gently pry the clip outward just enough to release the tension on the ball stud, then pull the strut away from the mount. Always have a second person support the weight of the lid while the struts are being detached.
Can I install gas struts upside down?
Most gas struts are designed to operate with the rod facing downward. This keeps the internal oil seal lubricated with the damping oil contained inside the cylinder. Installing them with the rod facing upward can cause the seal to dry out, leading to a loss of damping control and eventually a total loss of nitrogen pressure.
Secure your equipment reliability by sourcing high-performance gas struts that meet your exact dimensional and force requirements. Consult our technical catalog to match your measurements with our comprehensive inventory of industrial-grade replacements today.
