Sliding door running gear

A sliding door is only as good as its running gear. The leaf weight drives every choice.

Top-hung vs bottom-rolling

• Top-hung: the leaf hangs from carriages on a head track; a bottom channel or guide only stops it swinging. Smoother, quieter, keeps the floor clear — but the head structure must carry the full weight.
• Bottom-rolling: the leaf sits on rollers in a floor track. Simpler to support, but the track collects grit and the rollers wear faster. Common on aluminium patio sliders.

Sizing the carriages

Weigh a single leaf. Divide by the number of carriages (usually two). Choose carriages rated at least 1.5× the load per carriage. Undersizing is the number one cause of dragging doors a year later. Steel or nylon-tyred sealed-bearing wheels outlast open bushes.

The track

Match the track section to the carriage and to the leaf weight — a light interior track will deflect under a heavy glazed leaf. Aluminium track for interiors; heavier extruded or steel-reinforced track for large external sliders. Fix it to solid structure at close centres.

Soft-close and end stops

A soft-close (anti-slam) damper catches the leaf in the last 60–80 mm and eases it shut. Fit one at each end for a door that closes from both directions. Add positive end stops so the leaf cannot run off the track.

Guides and seals

A bottom guide keeps the leaf plumb; a brush or fin seal on the meeting and jamb closes the gap.

Send the leaf size, weight and material, and whether it is interior or a weather-facing external door, and we will spec the track, carriages and damper.