Vertical Feed Mixer Planetary Gearbox

Vertical feed mixer gearbox series — widely used on Italian and South American mixer brands. Confirmed OEM dimensional cross-reference available.

301R / 303R / 306R right-angle configurations used on self-propelled and electric-drive vertical mixers. Full Bonfiglioli 300R dimensional verification.

Cattlelac · Monomixer · Turbo Max · Schwartz · Val Metal · Gehl · Oswalt · Schuler · Lucknow · Keenan · Teagle · Buschhoff · and more — confirm by nameplate data.

The right-angle bevel input stage is the most mechanically demanding component in a vertical feed mixer gearbox — it must redirect the full PTO input torque by 90° while absorbing the shock loads of auger blockage events at up to 540 RPM input speed. Our bevel gear pair is Gleason spiral-cut and profile-ground for smooth, quiet, high-torque operation matching the Comer PGA1602 bevel geometry exactly.

One or two planetary stages after the bevel gear reduce speed from ~100–150 RPM (post-bevel) to the target output of 20–25 RPM, multiplying torque at each stage. Multiple planet gears share load simultaneously — this is why a planetary reduction in this torque class is far more compact than an equivalent worm or spur gear reduction — the torque density advantage is critical in the confined space of a vertical mixer bottom chamber.

All oil supply and return passages are machined directly into the ductile iron housing — eliminating the external hoses, fittings, and banjo bolts that are the primary oil-loss failure point on adapted industrial gearboxes used in feed mixing service. This matches the design philosophy of Auburn Gear VM Series, which defines the industry standard for integral oil passage construction.

The vertical auger output shaft must simultaneously carry auger weight (radial load), mixing torque (torsional load), and off-axis bale-processing forces (bending moment) — daily, for the life of the mixer. A one-piece forged 42CrMo alloy steel shaft eliminates all fretting corrosion and fatigue initiation points that develop at the fabricated joint interfaces of multi-piece shaft assemblies under these combined loads.

GGG-50 ductile iron housing provides the notch toughness and impact resistance needed for the mixer operating environment — where direct material impact from silage bales, stones in silage, and auger-ejected material is routine. Grey cast iron, commonly used in budget agricultural gearboxes, fractures under these impact conditions.

All planetary and bevel gears are manufactured from 20CrMnTi alloy steel, carburised, and hardened to 58–62 HRC with a case depth greater than standard industrial gearbox specification — to absorb the 3–5× rated torque spikes generated by bale processing and auger blockage events without tooth fracture. This is the most critical metallurgical specification difference between a purpose-built feed mixer gearbox and a general-purpose gearbox adapted to this application.

PTO Input — 540 RPM

The tractor PTO shaft — 6-spline at 540 RPM — drives the bevel pinion input shaft on the side of the gearbox housing. A shear bolt on the input shaft provides overload protection rated to protect the gearbox planetary gear set from damage if the auger stalls on a blockage. Input speed must not exceed 540 RPM.

Spiral Bevel Stage — 90° Turn

The bevel pinion meshes with the bevel ring gear mounted on the vertical centreline — redirecting power by 90° from horizontal PTO axis to vertical output axis. This is the most heavily loaded single gear mesh in the gearbox. The Gleason spiral bevel form provides smooth load transfer and higher tooth contact ratio than straight bevel alternatives.

First Planetary Stage

The bevel ring gear carrier drives the first-stage sun gear. Three or more planet gears share load across multiple contact points, multiplying torque while reducing speed. Power now flows vertically, coaxial with the auger output shaft, providing the first stage of the high torque multiplication needed for heavy TMR mixing.

Second Planetary Stage

A second planetary stage provides the final torque multiplication and speed reduction — bringing the output down to 20–25 RPM, the optimal auger speed for uniform TMR mixing of silage, dry forage, grains, and mineral supplements. Total ratio from PTO input to auger output is typically in the range of 20:1 to 27:1.

Vertical Auger Output — 20–25 RPM

The final stage carrier drives the one-piece forged alloy steel output shaft at 20–25 RPM. The output shaft connects directly to the auger coupling of the original mixer machine — splined or keyed shaft, matching the Comer PGA1602 or Auburn Gear VM output shaft interface exactly — so no modification to the mixer frame or auger coupling is required.

Dairy Farm TMR Mixing — 50 to 500+ Cows

The core application — daily total mixed ration preparation for milking cows. A vertical single-auger mixer handles 50–300 cow operations; twin-auger models handle 300–500+ head. The gearbox runs typically 1–4 hours daily, 365 days per year, under heavy silage, hay, and grain loads. This is the highest-duty-cycle application for any farm gearbox.

Beef Feedlot TMR Mixing

Large beef feedlot operations with 200–2000+ cattle typically use large-capacity vertical mixers (16–30 m³) driven by high-power tractors (200+ HP). These applications demand the heavy-duty VM30 or PGA2002 equivalent gearbox specification — our largest Feed Mixer Series sizes — with maximum torque output and shock load resistance for bale processing under high-power drive conditions.

Sheep & Goat Ration Preparation

Smaller vertical mixers (4–8 m³) in intensive sheep and goat operations require compact, lighter-duty gearboxes — typically the PGA1602 equivalent or VM10 size — run from smaller 60–100 HP tractors. The Feed Mixer Series' 20+ size range covers the smallest single-auger machines through to the largest commercial TMR systems from a single product family.

Stationary Electric-Drive TMR Systems

Large-scale commercial dairy and feedlot operations increasingly use stationary electric-drive TMR mixing systems — fixed mixers driven by electric motors and frequency inverters rather than tractor PTO. Our vertical feed mixer gearbox with IEC B5 electric motor input flange replaces the original PTO-drive gearbox in these fixed installations with the same output shaft interface and torque rating.

Self-Propelled Mixer Wagons

Self-propelled TMR mixers (Siloking, Faresin, Sgariboldi, and others) use hydraulic motor-driven vertical mixer gearboxes — the vehicle engine powers a hydraulic pump which drives the mixer auger through a hydraulic orbit motor on the gearbox. Our Feed Mixer Series with SAE A/B/C hydraulic motor flange replaces the original drive on self-propelled machines.

Truck-Mounted & Loader TMR Systems

Truck-mounted TMR mixer bodies and loader-lifted mixer buckets used in large commercial operations require vertical mixer gearboxes with hydraulic motor input — driven from the truck's hydraulic system or a tractor-mounted front loader hydraulic circuit. The Feed Mixer Series with hydraulic orbit motor input covers these configurations with the correct SAE flange and output shaft specification.

Read the Nameplate

Record gearbox brand (Comer, Auburn Gear, etc.) and full part/model number from the nameplate. Also note mixer machine brand and model if the nameplate is damaged.

Submit Cross-Reference

Send nameplate data to our team. We confirm the correct replacement model, dimensional match, and available stock within 48 hours — often same-day for Comer PGA1602 equivalent.

Confirm Options

Confirm PTO input speed (540 or 1000 RPM), output rotation direction (standard or reverse for twin-auger), and whether complete gearbox or planetary sub-assembly kit is required.

Receive Quotation

Price, lead time, installation drawing, and CE documentation reference supplied. For stocked models, same-day invoice and despatch notification typically available.

Tested & Shipped

FAT-tested at rated load, bevel contact pattern checked, packaged for agricultural supply chain handling. Test report, material certificates, and CE Declaration included.