Sliding Door Mechanisms Explained: Top Hung, Bottom Rolling, Synchro & Soft Close

Every sliding door is really three parts working together: a track, the gear that carries the door, and guides that keep everything in line. Get the mechanism right and the door glides for decades; get it wrong and you live with grinding, derailing and slamming. This guide walks through each mechanism type — top hung, bottom rolling, synchro and soft close — so you can match the engineering to your opening before you spend a penny.

If you want to jump straight to systems, our complete sliding door kit range lists track lengths and weight ratings on every product page.

Top Hung Mechanisms

The door hangs from rollers running inside an overhead track, with a small floor guide keeping it vertical. Because the weight hangs from above, the action is smooth and quiet, and there is no floor track to collect grit or trip over — the threshold stays completely clear.

The catch: the header above your opening must carry the full weight of the door. In stud walls that usually means adding a timber or steel header. Our top hung sliding door kits carry up to 120kg per door, which covers almost any domestic door including heavy hardwood.

Bottom Rolling Mechanisms

Here the rollers sit under the door, running on a floor track, with a top guide for stability. The floor carries the weight, so there is no structural requirement above the opening — which is why most fitted-wardrobe systems, like our wardrobe sliding door kits, are bottom rolling. The trade-off is a visible floor track that needs an occasional vacuum to keep the running smooth.

Synchro Mechanisms

A synchro system links two doors with a cable or belt so that moving one moves the other in the opposite direction — push one door and the pair opens symmetrically from the middle. It is the premium action for wide cabinet doors and room dividers, and it halves the effort of opening a big run. See it in action across our synchro sliding door kits.

Soft Close: Worth It?

A soft close damper catches the door near the end of its travel and settles it shut — no slam, no rebound gap, less impact wear on the gear. On bedroom wardrobes it is genuinely worth the extra cost; our PS-Slide systems include it both ways as standard, and retrofit soft close mechanisms can be added to E-Slide systems one door at a time.

Folding and Telescopic Variations

Two specialist mechanisms solve specific problems. Bifold gear hinges doors in pairs and folds them back, opening nearly the whole aperture — the answer when a slider's permanent overlap is too costly (see bifold door kits). Telescopic gear stacks two or three doors to one side at different speeds, giving the widest clear opening a slider can achieve.

Choosing in Practice

Three measurements decide it: opening width (sets track length — kits run 1200mm to 3000mm and trim to size), door count (keep each door under roughly a metre wide), and door weight (check the per-door rating; mirror and glass weigh far more than MDF).