Most operators spec a mixer on capacity, auger count, and gearbox rating. Tub geometry rarely makes the shortlist. That is a mistake, because the shape of the floor determines whether feed circulates or just spins, and that difference compounds into mix time, ration uniformity, and fuel burn across every batch you run.
What Happens Inside a Round Tub
A circular sidewall gives feed nowhere to go except around. The auger creates rotation, the wall maintains it, and the material keeps circling the same path. There is no lateral interruption to fold feed back into the cutting zone. Heavy ingredients, wet silage, the dense core of a round bale — all of them will happily orbit the auger without really engaging it. You can run the mix longer to compensate, but you are mostly extending spin time, not improving cut.
Dead spots form at the base of a round wall where the floor curve meets the sidewall. Dense or wet material packs into those zones and sits there. The auger does not reach it. The kicker barely touches it. By the time you open the discharge gate, that pocket of unpulled feed either stays behind or drops into the ration as an unprocessed lump.
How the Decagonal Tub TMR Design Breaks That Pattern
Ten flat sides, each set at a calculated angle to the next, change the physics of what happens at the wall. Feed traveling outward from the auger hits a flat panel rather than a continuous curve, and the angle of that panel redirects material back toward the center. Every pass produces a lateral deflection. Multiply that across ten sides and you get constant inward pressure rather than free rotation.
The practical result is that feed does not accumulate at the wall. It gets pushed back into the auger’s path on each revolution, which is where the cutting and folding action actually happens. Mix time drops because the auger is working on a full, moving charge rather than a core of circulating material surrounded by a stationary outer ring.
The geometry also addresses the dead-spot problem at the wall base. Because the flat panels interrupt outward flow rather than sustaining it, there is no stable orbit for dense material to settle into. What would pack against a round wall instead gets redirected. LEO Agriculture’s documented rationale for the design is that the ten-sided floor creates a near-perfect radius, capturing the flow benefits of a round tub while adding the redirecting action that flat panels provide. Nothing cosmetic about it.
If you want to understand how that geometry interacts with auger design at the cutting level, the square cutting principle behind the diamond auger is worth reading alongside this.
Kicker Sizing on a Decagonal Floor
Tub geometry and kicker sizing are not independent decisions. Get one wrong and the other underperforms.
The kicker sits at the outer lower leading edge of the auger. Its job is to scrape material off the floor, lift it, and pull it back into the auger. On a decagonal floor that is already redirecting feed inward, a correctly matched kicker produces what is called a rolling-boil condition: material cascades up the auger, falls outward, hits the wall panels, deflects inward, gets picked up by the kicker, and cycles again. That continuous turnover is what uniform TMR actually looks like from the inside.
Collapsed flow is the failure mode. It happens when the kicker is worn, undersized, or absent entirely. Feed packs near the floor and stagnates. The auger churns the upper portion of the charge while the bottom sits still. Torque demand rises because the auger is fighting compacted material rather than working a fluid, circulating mass. Fuel consumption follows torque up. Mix uniformity drops.
Kicker sizing should reflect ration type. High-hay rations and whole-bale programs put more long-stem material into the tub, which is bulkier and harder to pull back. A larger, more aggressive kicker is the right call there. Wetter rations with a lot of silage need less bite — an oversized kicker in a wet mix just slings material without improving flow. The bolt-on design matters here because ration composition changes seasonally, and what worked in summer on green chop may not be right in winter on dry hay and straw.
Running without a functioning kicker degrades mix quality and raises costs. That is not a qualifier — it is just what happens.
Whole-Bale Processing and the Geometry Payoff
Whole-bale programs are where tub shape makes the biggest measurable difference. A round bale dropped into a circular tub will spin against the wall almost indefinitely if the auger geometry is not aggressive enough to grab it. The wall offers no resistance, so the bale just orbits. Processing time stretches out, and the outer layers peel off without the core getting worked.
On a decagonal floor, the flat panels create contact pressure rather than a free-spinning surface. The bale cannot maintain a clean orbit. It gets interrupted, repositioned, and pulled back into the auger’s reach. Paired with angled ripping blades designed for bale teardown, the processing time drops significantly. Auger flow innovations built around bale processing are only fully effective when the tub shape is cooperating with them.
What to Check Before You Buy
Tub geometry is not something you can evaluate from a brochure photo. Ask the manufacturer for the design rationale behind their sidewall shape. Circular, octagonal, and decagonal floors all behave differently, and the claimed capacity of a machine tells you nothing about which shape it uses or why.
Check kicker options early. A machine that only offers one kicker size gives you no ability to tune for ration changes. Bolt-on kicker systems in multiple sizes are a practical feature, not a luxury.
Pay attention to floor wear patterns on used machines or demo units. Uneven wear concentrated near the wall base is a sign of poor wall geometry or a failed kicker. Even wear across the floor means the material was circulating properly.
For operators working through mixer selection for the first time, tub shape deserves at least as much attention as auger count. The auger works the feed. The tub shape determines how much of that feed gets delivered to the auger in the first place.
