For a Cantilever Slide Gate, what is the typical back frame length relative to the opening?

• A. Half the length of the opening
• B. The full length of the opening
• C. A quarter of the opening length
• D. Equal to the roadway width

Answer: (A)

In a cantilever slide gate, the back frame serves as the stabilizing anchor behind the opening, carrying the load and keeping the gate aligned as it slides along the track. The typical approach is to make the back frame about half the length of the opening. This length provides enough mounting surface and stiffness to resist the bending and movement of the gate without adding unnecessary weight or cost.

If the back frame were as long as the opening, you’d be overbuilding and complicating installation without added benefit. If it were only a quarter of the opening, the anchorage and support might be insufficient, risking sag or misalignment. The back frame length being tied to the opening length (and not to the roadway width) ensures the frame supports the gate where it matters for proper operation.