Understanding Gas Spring Specifications: Stroke, Extended Length, and Force

Looking at a gas spring datasheet can be confusing. What do all those dimensions mean? To ensure you order the right part, you need to understand three key specs: Extended Length, Stroke, and Force.

1. Extended Length (EL)

This is the total length of the gas spring when it is fully open (uncompressed).

• How to measure: Usually measured from the center of one end fitting to the center of the other (Center-to-Center).
• Why it matters: It determines if the spring physically fits in your space when the lid is open.

2. Stroke (S)

This is the travel distance of the piston rod. It is the difference between the Extended Length and the Compressed Length.

• Formula: $Compressed Length = Extended Length - Stroke$ (roughly).
• Why it matters: Your lid needs to open a certain distance. If the stroke is too short, the lid won't open fully. If it's too long, the spring might bottom out before the lid closes.

3. Force (F1)

This is the strength of the spring, measured in Newtons (N).

• F1: The force measured just before the spring is fully extended (usually 5mm from full extension).
• Conversion: 100N ≈ 10kg (22 lbs).
• Why it matters: It lifts the weight. (See our previous post on Force Calculation).

4. Tube/Rod Diameter (e.g., 6/15, 8/18, 10/22)

Gas springs are often categorized by their series, which refers to the rod and tube diameter in millimeters.

• 6/15: 6mm rod, 15mm tube (Light duty, up to 400N).
• 8/18: 8mm rod, 18mm tube (Standard duty, up to 800N).
• 10/22: 10mm rod, 22mm tube (Heavy duty, up to 1200N).
• 14/28: 14mm rod, 28mm tube (Super heavy duty, up to 2500N).

Reading a Part Number

A typical part number might look like: G0818-500-200-400N

• G0818: Series 8/18
• 500: Extended Length (mm)
• 200: Stroke (mm)
• 400N: Force

Now you speak the language of gas springs! Check your drawings and order with confidence.