TL;DR
Drive overload means the mixer motor is drawing above rated current. Check fill level, ingredient bulk density, and paddle condition before increasing the motor size.
What you might see
- motor overload relay tripping
- motor current above nameplate FLA under load
- mixer slowing down under a full batch
- drive belt or coupling showing wear
Likely causes
Mixer overfilled beyond rated capacity, increasing torque demand
Ingredient bulk density higher than the design basis for this mixer model
Paddle clearance reduced by wear, increasing drag on the mixer shell
Gearbox oil degraded, increasing internal friction
Required tools
- Clamp ammeter (true-RMS)
- Feeler gauge for paddle clearance
- LOTO kit
Safety first
- Lock out the mixer before measuring paddle clearance or inspecting the gearbox. Never reach into a mixer that is not locked out.
- Energized electrical measurement requires category-rated PPE.
Procedure
- 1
Measure motor current with a clamp ammeter at the motor terminals under load. Compare to the nameplate FLA.[1]
- 2
Reduce the batch fill level by 10% and recheck motor current. If current drops below FLA, overfilling is the cause.
- 3
Check the bulk density of the current ingredient recipe. High-density ingredients (minerals, wet distillers grains) can push torque above the design limit for a given fill level.[1]
- 4
Lock out the mixer and check the paddle-to-shell clearance at multiple points. Reduced clearance from paddle wear or shell deformation increases drag.
- 5
Check the gearbox oil level and appearance. Discolored or milky oil indicates moisture ingress and requires a full oil change.
- 6
Verify that the overload relay setpoint has not been adjusted above the motor nameplate. An incorrect overload setting masks a real overload condition.
- 7
If motor current is at or above FLA at the rated fill level and normal ingredient density, the drive sizing should be reviewed before further operation.
Sources
Bühler Bühler MWBA Feed Mixer / Blender general technical documentation, Bühler
Feed mixer drive system diagnostics and motor current measurement, general feed manufacturing practice (general)
More guides for Bühler Bühler MWBA
How to fix low blend uniformity on a Buhler MWBA Feed Mixer
Low blend uniformity means ingredients are not homogenized. Check mixing time, fill level, paddle condition, and the ingredient addition sequence before increasing mixing time.
How to fix a discharge gate that will not seal on a Buhler MWBA Feed Mixer
A leaking discharge gate wastes ingredient and cross-contaminates batches. Inspect the gate seal and pneumatic actuator, and clean the gate seat before replacing the seal.
Stop fixing the same fault twice.
Dovient turns guides like this into your team's shared playbook, with AI that catches recurring issues before they break the line.