Balancing services › Combines & Harvesters
Combine Harvester Rotor Balancing — In-Situ, at Operating Speed
Threshing drums, straw choppers, rotary separators and cleaning fans lose balance as blades wear, blades are replaced or crop residue accumulates asymmetrically. We balance these rotors on the machine, in the field, at working RPM — no dismantling, no transport to a workshop — so your combine is harvest-ready before the season and stays that way.
In short: Combine harvester rotor balancing is performed in-situ, at normal threshing or chopping speed, using the influence-coefficient method. A vibration accelerometer on the bearing housing and a laser tachometer on the shaft measure the unbalance state; the Balanset-1A calculates the exact correction mass and angular position — in one or two planes as required. No rotor removal, no workshop visit — a typical job is complete in under one hour, reducing vibration by 70 % or more and multiplying bearing and belt life accordingly.
Signs a combine rotor is out of balance
Threshing drums and straw choppers take severe mechanical stress every season — the symptoms of rotor unbalance are hard to miss from the cab or workshop:
Why combine rotors lose balance — and what it costs
A threshing drum or straw chopper leaves the factory balanced, but every season of field work gradually shifts that balance. Worn or replaced blades and hammer flails change the mass distribution; bent beaters alter the geometry; uneven crop and mud build-up adds non-uniform mass; abrasive erosion removes material faster on exposed faces; and weld repairs inevitably place more metal on one side than the other. Because centrifugal force grows with the square of rotational speed, a 50 g offset at 800 rpm — typical threshing-drum speed — generates a shaking force of around 300 N. At 1,200 rpm (straw-chopper speed), the same offset exceeds 700 N.
Left uncorrected, that cyclic force destroys bearings and belts, cracks the drum body and the frame around it, degrades grain-separation quality (separation losses rise as the drum vibrates), and forces an unplanned stop mid-harvest. A single field-balancing session — typically under one hour, on the machine — removes the root cause instead of repeatedly replacing the components it destroys.
Why halving vibration multiplies bearing life
How we balance a combine rotor — step by step
Field balancing with the Balanset-1A follows the influence-coefficient method — the same systematic procedure you can carry out yourself, on the machine, in the field:
- Mount the sensors. A vibration accelerometer is fixed to the drum or chopper bearing housing and a laser tachometer is aimed at a reflective strip on the shaft. No disassembly is required — the rotor runs at normal operating speed throughout.
- Measure the baseline. One run at full working speed records vibration amplitude and phase angle, establishing the current unbalance state in magnitude and direction.
- Add a trial weight. A known test mass is clamped or temporarily bolted to the drum end-plate, chopper flange or rotor disc. A second run shows how the rotor responds to that mass at a known angular position — the influence coefficient.
- Let the device calculate. The Balanset-1A applies the influence-coefficient algorithm to compute the exact correction mass and angular placement — one plane for short cleaning fans and feeder rotors, two planes for long threshing drums and straw choppers.
- Fit the correction weight. Weld, bolt or clamp the calculated mass at the indicated angular position on the drum end-disc, blade carrier or chopper flange. Remove the trial weight unless it forms part of the solution.
- Verify and document. A final measurement run confirms residual unbalance is within the ISO tolerance band for the rotor’s balance grade. The Balanset-1A saves a balancing report for your maintenance records.
What we balance on combines & harvesters
- Threshing drums & beaters
- Straw choppers & spreaders
- Rotary separators & straw walkers
- Cleaning & cooling fans
- Feeder-house rotors
- Mulcher & flail rotors
- Augers & conveyor screws
- Drive shafts & belt pulleys
- Forage-harvester cutter drums
- Corn-header gathering chains & snapping rolls
Tolerances & standards
ISO 21940-11 (formerly ISO 1940-1) defines rigid-rotor balance quality grades from G0.4 to G4000. Agricultural rotor types and their recommended grades:
| Rotor type | Recommended grade | Permissible residual unbalance (example: 80 kg rotor at 800 rpm) |
|---|---|---|
| Threshing drum (field crop) | G6.3 | 750 g·mm total |
| Straw chopper / flail rotor | G6.3 | 750 g·mm total |
| Cleaning fan & cooling fan | G2.5 | 300 g·mm total |
| Feeder-house / rotary separator | G6.3 – G16 | Application-dependent |
We balance to the grade your application demands and document the achieved residual unbalance in a report so you have a verifiable record. Use our residual-unbalance calculator to find your permissible tolerance before starting.
The Balanset-1A — your complete field-balancing kit
Everything on this page is done with one portable instrument: the Balanset-1A. It is a two-channel dynamic balancer and vibration analyzer that balances combine-harvester rotors — threshing drums, straw choppers, rotary separators — in their own bearings, at operating speed, using the 3-run influence-coefficient method — the software calculates the exact correction mass and angle and saves a report.
What’s in the Full Kit
€1,975 · Full Kit, in stock, VAT invoice
- Interface measurement unit (USB, 2 channels)
- Two vibration accelerometers (4 m cable, 10 m optional)
- Laser tachometer / optical phase sensor (50–500 mm)
- Magnetic stand for the sensor
- Digital scale for trial & correction weights
- Windows balancing & analysis software
- Plastic transport case
Full Kit
Unit · 2 sensors · laser tachometer · magnetic stand · digital scale · software · transport case. Everything needed to start balancing out of the box.
OEM set
Unit · 2 sensors · laser tachometer · software. For integrators who already have a stand, scale and case, or who embed the unit into a balancing machine.
| Parameter | Value |
|---|---|
| Measurement channels | 2 (single- & two-plane balancing) |
| Vibration velocity range | 0.05–100 mm/s |
| Frequency range | 5–300 Hz |
| Measurement accuracy | ±5% of full scale |
| Method | 3-run influence-coefficient (1 or 2 planes) |
| Analysis | Amplitude & phase at 1×, FFT spectrum & waveform, saved reports |
| Laptop | Not included (Windows PC, available on request) |
Field balancing vs balancing machine — which is right for your combine?
| Factor | Field balancing (Balanset-1A) | Balancing machine (workshop) |
|---|---|---|
| Rotor removed from combine? | No — runs in place | Yes — full disassembly required |
| Transport to workshop? | No | Yes — drum or chopper must be extracted |
| Machine downtime | Sensor fitting only (<15 min) | Hours to days (pull, transport, balance, reinstall) |
| Balancing speed | Actual operating speed & crop load | Separate low-speed spindle, no crop load |
| Accounts for shaft flex & mounting | Yes — full assembly balanced | Drum body only, mounting not accounted for |
| Standards met | ISO 21940-11, G-grade documented | ISO 21940-11 |
| Equipment cost | €1,975 (Full Kit) | €10,000 – €50,000+ |
| Typical job time | <1 hour on site | 1–3 days total |
Field balancing is the preferred choice whenever the combine rotor can be run and the rigidity criterion is satisfied. A workshop machine remains appropriate for new-build drums before initial assembly, or when the rotor must be removed for other repair work anyway.
Real combine-balancing cases
Combine harvester with Balanset-1A
Step-by-step field balancing of a threshing drum on a working combine, with documented before/after results.
Savings on repairs & maintenance
Troubleshooting the combine balancing process — real-world reduction in bearing and belt replacement costs.
Mulchers & rotating elements
Balancing the diverse rotors found in modern combines — mulchers, choppers and feeder-house assemblies.
Free calculators
Combine balancing FAQ
Do you have to remove the drum or chopper to balance it?
One plane or two planes — which does a threshing drum need?
How long does a typical combine balancing job take?
When should I balance — before or during harvest?
Can our maintenance team do it themselves?
What balance grade does a threshing drum need to meet?
Learn the theory
Balance your combine rotors in the field — before harvest
The Balanset-1A guides you through single- and two-plane balancing of threshing drums, straw choppers and rotary separators at actual working speed, calculates the exact correction weight and angle, and documents the result to ISO 21940-11. No dismounting, no lost harvest days — just smoother, longer-lasting rotors.
