Every scrubber dryer is available with one of two deck types, and the choice matters more than the brand. Getting it wrong means either poor cleaning or unnecessary work before every pass.
Disc decks
A disc deck runs one or more flat brushes or pads horizontally against the floor. All of the machine’s down pressure is concentrated on a small contact area, which is what makes a disc deck good at removing bonded soil: rubber marks, grease films, ground-in dirt on sealed concrete.
Discs also accept pads as well as brushes, so the same deck strips, scrubs and polishes depending on which pad is fitted. On smooth hard floors with light debris, a disc deck is usually the right answer.
The weakness is loose debris. A disc brush pushes anything larger than grit ahead of it into a windrow, and then the operator has a line of debris to deal with at the end of the run.
Cylindrical decks
A cylindrical deck runs counter-rotating rollers, like a sweeper. Debris is thrown up into a hopper on the deck instead of being pushed along the floor, so the machine sweeps and scrubs in one pass. On a floor with screws, packaging, food waste or leaf litter from a doorway, that removes a whole sweeping operation from the schedule.
Cylindrical decks also handle textured and profiled surfaces better, because the roller reaches into a grout line or a safety-profile tread in a way a flat disc cannot.
The trade-off is pressure. The same machine weight spread across a much larger contact area means less pressure per square centimetre, so a cylindrical deck is weaker on bonded soil.
Choosing
Bonded soil on a smooth floor, little loose debris: disc. Loose debris, grout lines, profiled or non-slip surfaces: cylindrical. Both problems together on a large floor: sweep first with a mechanical sweeper, then scrub with a disc deck. That is more machines, but on a floor with both problems it is usually faster than trying to make one deck do everything.
Before you decide
Walk the floor at the end of a normal shift, not first thing in the morning. What is on it then is what the deck has to deal with, and it is often not what the specification meeting assumed.
Then check what the deck costs to run. Disc brushes and pads are cheap and quick to change, and pads are consumed steadily. Cylindrical rollers last longer but cost more per set, and the debris hopper has to be emptied and rinsed at the end of every use or the deck starts to smell within a week. Neither is expensive, but only one of them is a daily task, and that belongs in the cleaning schedule before the machine arrives rather than after.
