Example Data Table
| Use Case |
Mass kg |
CG mm |
Lid Bracket mm |
Fixed X mm |
Fixed Drop mm |
Open Angle |
Springs |
| Small cabinet lid |
8 |
220 |
170 |
60 |
90 |
75 |
1 |
| Machine guard |
18 |
320 |
240 |
80 |
120 |
70 |
2 |
| Heavy access hatch |
35 |
450 |
340 |
110 |
170 |
65 |
2 |
Formula Used
The calculator treats the lid as a rotating beam about the hinge. Weight force is calculated as mass multiplied by gravity.
Weight force: W = m × 9.80665
Lid torque: T = W × CG × cos θ
Spring length: L = √((x₂ - x₁)² + (y₂ - y₁)²)
Moment arm: d = |P × spring line| ÷ L
Required force per spring: F = design torque ÷ (spring count × open moment arm)
Design torque includes assist percentage, friction allowance, safety factor, temperature allowance, and target handle effort.
How to Use This Calculator
Enter the lid mass, center of gravity distance, and hinge geometry. Add the moving bracket distance on the lid. Then enter the fixed bracket offset and drop from the hinge.
Use zero degrees for a horizontal closed lid. Enter the planned open angle. Set the number of springs, assist level, and safety factor. Leave selected force at zero when you want the tool to estimate the required spring force.
After calculation, review the stroke, compressed length, extended length, force, support share, and design note. Export the result when you need a design record.
Gas Spring Mounting Position Guide
A gas spring does not only need the right force. It also needs the right brackets. A small change in bracket position can change the lift moment, stroke, and closing feel. This calculator models the lid as a rotating beam around one hinge. It then compares the lid torque with the torque supplied by each gas spring.
Why Mounting Geometry Matters
The moving bracket radius controls leverage. A larger radius usually gives the spring more moment arm, but it also increases required body length. The fixed bracket controls the spring angle. A poor angle can create high force with weak lifting torque. Good geometry keeps the spring within stroke, avoids over extension, and gives smoother support near the open position.
How Results Should Be Used
Use the required force as a design estimate. Choose the nearest standard gas spring rating after checking manufacturer limits. Always confirm closed length, extended length, end fittings, ball stud clearances, and stop positions. Real lids may include seals, friction hinges, wind, vibration, or uneven weight distribution. These effects justify a safety factor, but excessive safety can make the lid hard to close.
Design Checks
The calculator shows open length, closed length, usable stroke, moment arm, and support share. If the support share is low, move the lid bracket farther from the hinge or adjust the fixed bracket drop. If the stroke is too long, reduce bracket spacing or select a longer spring. If the closing effort is high, lower the selected force or reduce the assist percentage.
Practical Mounting Notes
Mount gas springs rod down where possible. This helps lubrication and seal life. Keep brackets aligned so side load is low. Use two springs for wide panels when twisting is possible. Test the assembly slowly before final drilling. Mark the open and closed positions. Check that the spring never becomes the hard stop unless the product is designed for that duty. A separate mechanical stop is safer for many covers.
This tool is useful for cabinets, machine guards, hatches, storage lids, and access panels. It gives a structured starting point before prototype testing and supplier review.
Document every chosen dimension, because repeatable notes reduce mistakes during fabrication and maintenance reviews.
FAQs
1. What is a gas spring mounting position?
It is the selected location of the fixed bracket and moving lid bracket. These points control spring length, stroke, angle, leverage, and support torque.
2. Why does bracket distance change the required force?
Force works through a moment arm. A better angle or longer bracket radius can create more torque from the same spring force.
3. Can this calculator choose the final gas spring?
It gives an engineering estimate. Final selection should confirm supplier limits, end fittings, stroke margin, pressure rating, and physical clearance.
4. Should I use one or two gas springs?
Use two springs for wide, heavy, or flexible panels. Two springs reduce twisting and divide force between both sides.
5. What does selected gas spring force mean?
It is an optional known spring rating. Enter it to check support share and estimated handle effort against your planned geometry.
6. Why is a safety factor included?
A safety factor allows for friction, wear, seals, uncertain weight, mounting tolerance, and small calculation errors. Avoid making it excessive.
7. What happens if the moment arm is low?
The spring has poor leverage. The required force rises, and the lid may feel weak or uneven near the open position.
8. Should the spring be the opening stop?
Usually no. A mechanical stop is safer because it protects the spring, brackets, and hinge from repeated impact loads.