PGA Series Auger Drive Planetary Gearbox for Feed Mixer

PGA Series Auger Drive Planetary Gearbox for Feed Mixers and TMR Wagons

The PGA series is the auger drive unit that sits between the tractor PTO and the mixing screw of a feed mixer. A 540 rpm input from the tractor is reduced through a planetary stage to the low, high-torque rotation the auger needs to lift and fold silage, hay and concentrate without stalling. Because the load path is shared across several planet gears, the drive stays compact enough to bolt onto the mixer's front or side plate while still producing continuous torque from 3,810 N·m on the smallest model to 42,000 N·m on the largest.

Raydafon builds the PGA series in its own workshop in Ningbo, China, under an ISO 9001 quality system, and supplies it to feed mixer and diet feeder manufacturers as an OEM unit as well as to dealers as a replacement gearbox. If your machine is PTO driven, pair it with a PTO shaft for feed mixers; if your mixer uses a bevel stage instead of a planetary one, compare the feed mixer gearbox range on the same site.

What Is an Auger Drive Planetary Gearbox and How Does It Work?

An auger drive planetary gearbox is a coaxial reducer in which a sun gear drives several planet gears that rotate inside a ring gear while carried by a planet carrier. Torque is therefore transmitted through multiple tooth contacts at once instead of a single pair, which is why a planetary unit can carry a heavy mixer load in a short, round housing and why it resists the shock that occurs when a full auger starts up in frozen or compacted feed.

In a feed mixer the sequence is straightforward: tractor PTO at 540 rpm, planetary reduction to roughly 5–50 rpm at the auger shaft, and a torque multiplication that lets a comparatively small tractor turn a large mixing screw. That is also why the PGA series is chosen by farms running small tractors — the gearbox, not the tractor, supplies the extra turning force. The same principle applies to silage and biogas plant feeders, where continuous low-speed rotation matters more than peak speed.

Technical Specifications and Model Range

• Max torque is the intermittent peak the gearbox accepts during start-up of a loaded auger; continuous torque is the value for uninterrupted mixing duty.
• Input shaft options shown are the standard 1"3/8 Z6 and 1"3/4 Z20 PTO profiles. Other splines, bore sizes and output flange dimensions can be machined to your drawing.
• Ratios outside the range listed for a given frame can sometimes be reached by combining stages — send the required output speed and we will confirm.

How to Choose the Right PGA Model for Your Mixer

1. Match frame to tractor power and auger size. Small 40–80 hp mixers usually run PGA-502 or PGA-1002/3; mid-range 80–150 hp TMR wagons typically use PGA-1602/3 to PGA-2502; large vertical mixers and biogas feeders move up to PGA-3004 or PGA-4204.
2. Check continuous torque against your duty. Compare the mixer's required auger torque with the continuous figure in the table, not the peak figure. The peak value is headroom for start-up, not a working rating.
3. Confirm the input shaft. Most tractors in Europe and North America use 1"3/8 Z6 at 540 rpm, while larger machines use 1"3/4 Z20. The wrong spline is the most common ordering error we see.
4. Check mounting and oil level. Confirm the bolt pattern, output flange and oil filler position against the mixer frame so the unit sits at the angle specified in the manual.
5. Plan the maintenance interval. Use the oil grade and change interval in the manual; we can supply a written maintenance schedule with the shipment if your service team needs one for warranty records.

Not sure which frame fits? Send the mixer brand, auger diameter, tractor horsepower and required auger speed — our engineers will confirm the model and ratio before you order.

Product Detail

Both photographs below are the PGA series unit we produce: the assembled gearbox with its cast housing and PTO input, and the dimension drawing used for mounting checks.

Materials, Sealing and Build Quality

Gears and heat treatment

Gears and shafts are machined from high-strength alloy steel and gas carburized, then quenched to a tooth-surface hardness of about HRC58 while the core stays tough enough to absorb shock. That combination is what gives the PGA series its wear resistance on abrasive silage and its tolerance of repeated loaded starts, and it is the reason the same frame can be offered across a wide ratio range without changing the external envelope.

Housing and sealing

The housing is a one-piece cast-iron body, which keeps the bearing bores concentric and damps the vibration that a fabricated housing would transmit. Dual sealing on the input and output ends holds the lubricant in and keeps dust, slurry and wash-down water out, giving the unit an IP65 protection level. Grease nipples and the oil fill point are positioned so routine servicing can be done with the mixer in its working position.

Testing before dispatch

Every gearbox is run and checked before packing: no-load running to confirm smooth rotation and oil sealing, backlash and contact-pattern verification on the gear set, and a final inspection of the input spline and output flange. Test records can be attached to the shipping documents when your project requires documented evidence.

Key Advantages for Feed Mixer Operators

1. Lower fuel cost. High transmission efficiency means less power is lost between PTO and auger, cutting fuel use by roughly 30% on comparable mixing work.
2. Faster start, no preheating. The gear set reaches working state quickly, so early-morning batches and top-up mixes do not need a long warm-up.
3. Stable high-speed mixing. The precision gear set keeps auger speed steady through hay, silage and concentrate, so the ration mixes evenly instead of stratifying.
4. Smoother, longer-lasting drive. A symmetrical planetary layout balances the transmission force, reducing jamming loads and mechanical wear on the whole driveline.
5. Automatic ratio shifting under load. The unit starts in a high-torque mode that breaks up compacted or frozen feed, then shifts to a faster mode for the rest of the batch.
6. Works with small tractors. Torque amplification lets a smaller, cheaper tractor drive the same auger, freeing larger machines for other field work.
7. Longer PTO driveline life. Low starting torque reduces shock on the tractor PTO and the shaft coupling, extending coupling replacement intervals by 2–3 times.
8. Quieter, more stable operation. Multi-tooth meshing absorbs transmission vibration, lowering noise and the risk of fasteners working loose.
9. Easier operation. Automatic shifting reduces manual intervention, so the operator watches the ration and the machine rather than the gearbox.
10. Documented quality. ISO 9001 production, machined and assembled in our own factory, with spare parts and technical support after delivery.

Fuel-savings and service-interval figures above are based on our gearbox design and typical feed mixer duty; actual results depend on tractor, ration and operating conditions.

Available Configurations and Mounting

The PGA series is supplied as a solid, compact planetary transmission that bolts into three common mixer layouts. Tell us which one you build or run, and the output flange, mounting face and oil fill position are set accordingly.

Applications

The PGA series drives the rotation of feed mixers and biogas plant feeding systems. Typical installations include:

• Vertical and horizontal TMR feed mixers and diet feeders
• Auger and screw conveyors in feed centres and on-farm feed kitchens
• Silage and straw mixing lines where compacted material must be broken up
• Biogas plant feedstock mixers and dosing screws running continuous duty
• Bedding and litter spreaders using the same auger drive principle
• Retrofit replacement of worn gearboxes on existing mixers of other brands

If your machine is not on this list, describe the application and duty cycle. A gearbox that suits a stationary biogas feeder may need a different oil specification or mounting angle for a truck-mounted TMR wagon.

Customer Reviews

Buyer FAQ

• Which PGA model fits my feed mixer?Match tractor horsepower, auger diameter and required auger speed to the continuous torque column: 40–80 hp mixers usually take PGA-502 or PGA-1002/3, 80–150 hp TMR wagons take PGA-1602/3 to PGA-2502, and large vertical mixers or biogas feeders take PGA-3004 or PGA-4204. Send us your mixer details and we will confirm the model and ratio.
• What is the difference between continuous torque and max torque?Continuous torque is the rating for uninterrupted mixing; max torque is the intermittent peak the unit accepts when a loaded auger starts. Size the gearbox on the continuous figure and treat the peak as start-up headroom.
• Which PTO input shaft do I need?The standard options are 1"3/8 Z6 for most 540 rpm tractors and 1"3/4 Z20 for larger machines. If your PTO is a different spline, bore or size, send the drawing and we will machine the input to match.
• Is the gearbox protected against dust and water?Yes. The cast-iron housing uses dual sealing on the input and output ends to an IP65 protection level, which covers the dust, slurry and wash-down conditions of daily farm use.
• Can I order a custom ratio, flange or housing finish?Yes. Raydafon machines the gears and assembles the units in its own factory, so custom ratios, output flanges, mounting faces, oil fill positions and paint finishes are produced to drawing for OEM programs.
• What about lead time, spare parts and warranty?Standard frames ship on a short schedule and custom units follow the confirmed drawing. Spare gear sets, seals and bearings are available separately, and warranty terms are stated on the quotation. Send your quantity and delivery port for a firm price within 24 hours.

Related Products and Further Reading

Raydafon supplies the whole drive train around a feed mixer, so you can order the gearbox, the shaft and the couplings from one factory and one inspection standard:

• PG series feed mixer planetary gearbox — alternative frame for mixers already using the PG mounting pattern.
• Feed mixer planetary gearbox — the full category, including sizes above and below the PGA range.
• PTO shaft for feed mixers — matched driveline with the correct spline, guard and length for your tractor.
• Feed mixer gearbox — bevel and helical options when a planetary unit is not the right fit.