Gas spring for a drop-down flap

A drop-down flap is hinged at its bottom edge and folds down and out. Without support it falls open; pull gas springs (traction springs) inside the cabinet hold it back.

The calculator chooses the pull springs and mounting points, and shows whether the flap stays put, opens gently or falls, from closed to fully open.

Tips

Pull springs pull their ends together: they hold the flap back as it opens.
Use "Let go at …°" to check the flap does not slam open.
Add the weight of a handle or lock as extra weight at the front edge.