A worn or wrongly sized kicker is one of the most overlooked causes of slow mixing and high fuel burn. Operators spend time chasing mix uniformity problems through knife layout and load order when the real issue is a bolt-on part at the base of the auger. Get the sizing right and everything else gets easier.
What a Kicker Actually Does
The kicker sits on the outer, lower leading edge of the vertical auger. Its job is to scrape feed off the tub wall, lift it, and redirect it back toward the auger so it keeps circulating. That continuous rolling motion is what gives a vertical mixer its characteristic tumbling action. Without it, or with a kicker that is too small for the ration, material stagnates at the wall instead of cycling through the cutting zone.
That stagnation has a name: collapsed flow. Feed packs against the wall, the auger churns the same material near the center, and you end up extending mix time trying to achieve uniformity that the machine physically cannot deliver in that condition. Torque demand goes up, fuel burn follows, and the ration still comes out inconsistent.
The fix is not always a new machine. Sometimes it is a five-minute bolt swap.
Sizing Logic: Aggressiveness Should Scale With Hay Content
Kickers are not one-size-fits-all. The general rule is straightforward: the more dry roughage in the ration, the more aggressive the kicker needs to be.
High-roughage rations built around long-stem dry hay are the hardest case. Dry hay is low density. It floats, it bridges, and it resists the natural flow pattern inside the tub. A small or medium kicker simply cannot generate enough wall movement to fold that material back into the auger reliably. You need a Large kicker, or in the most demanding applications, an Extreme.
Wet rations are the opposite problem. High-silage TMR is dense and heavy. It moves readily on its own, and an oversized kicker will over-work it. That drives up torque demand without improving mix quality. A Medium or Small kicker keeps the material cycling without grinding against resistance that does not need to be there.
The practical sizing guide looks like this:
- Dry hay or straw-heavy rations: Large or Extreme
- Mixed rations with moderate roughage: Medium
- High-moisture silage with minimal dry hay: Small
The Extreme Kicker: Built for Light-Density Material
The Extreme is a Large kicker with an added lip. That lip is the difference for operations running straw or dry hay as a significant portion of the ration.
Low-density material like straw does not cooperate the way silage does. It floats toward the top of the tub, bridges across wall sections, and resists being pulled back into the high-pressure cutting zones near the base of the auger. A standard Large kicker helps, but the added lip on the Extreme creates a more aggressive sweep, effectively scooping that floating material rather than just nudging it. The result is that feed that would otherwise stagnate at the wall actually gets folded back into circulation.
If you are running whole-bale dry hay and finding that your mix times are long even with a functioning large kicker, the Extreme is worth trying before you start adjusting anything else.
It is also worth understanding how kicker design connects to the broader auger flow system. The kicker works in combination with the leading edge geometry of the auger itself. Some auger designs incorporate a V-shaped leading edge that acts like a grader blade, naturally pushing material toward center and reducing the horsepower needed to keep feed moving. When that geometry is working alongside a correctly sized kicker, processing speed improves and fuel demand drops. You can read more about how those auger flow innovations interact in practice.
Seasonal Ration Changes and the Case for a Spare Kicker on the Shelf
Many operations feed fundamentally different rations across the year. Winter feeding often leans on dry hay when pasture is gone and silage stocks are being managed carefully. Summer brings high-moisture silage, fresh-cut material, and less reliance on dry roughage.
Those rations have different kicker requirements. Feeding through a winter hay program with a Medium kicker sized for a wet summer ration means accepting degraded mix uniformity for months. Most operations do not swap kickers seasonally because nobody told them it was a five-minute bolt job. It is. The part comes off with a few bolts, the replacement goes on the same way, and the machine is back to work.
Keeping two kicker sizes on the shelf costs less than the fuel wasted running the wrong one through a season. For operations that also vary ration composition between animal groups, having the right kicker matched to each program is worth building into the feed management routine rather than treating as a one-time setup decision.
This approach to kicker swapping fits naturally into a broader philosophy around commercial TMR mixer maintenance: bolt-on wear items should be treated as adjustable parameters, not as fixed parts that only get replaced when they fail.
What Happens When You Run Without One
Some operators pull a worn kicker and keep running while they wait for a replacement. The machine still turns. Feed still moves. But the mix quality drops visibly over time, and extended mix cycles push tractor hours up without delivering a better result.
A worn kicker leaves dead spots at the tub wall. Material packs rather than circulates. Clean-out at the end of the cycle is slower and less complete, which creates carryover between batches. None of that shows up as a fault code. It just quietly costs money.
For smaller operations where total herd size makes a compact machine the right fit, the same kicker sizing principles apply. The mini mixer range runs the same bolt-on system, so operators moving between dry hay and wet ration programs can dial in aggressiveness the same way regardless of machine size.
Knife Layout Is a Separate Variable
Kicker size and knife layout both affect mix performance, but they are not interchangeable levers. Knife placement governs where cutting pressure is applied in the tub’s vertical zones. The kicker governs wall-to-auger material flow. Adjusting one when the problem belongs to the other wastes time.
A rough guide on knives: pre-chopped roughage typically benefits from a large knife in the top position, while round bales and alfalfa generally run better with a small knife on top. High-density silage rations with little roughage can often carry a large knife at top without issue. But if feed is stagnating at the wall and mix times are long, check the kicker before rearranging the knife layout. The kicker is more likely to be the constraint.
LEO Agriculture documents four bolt-on kicker sizes, Small through Extreme, across their VT and HD vertical mixer lines. The sizing logic above applies to those machines, and it applies equally to any vertical mixer from any manufacturer that uses a leading-edge kicker design. The principles do not change with the badge on the side.
