Bareco Post Hole Digger Gearboxes and Augers: Choosing the Right Setup for Your Tractor

Last updated June 2026

A tractor-mounted post hole digger is one of the most practical implements on an Australian farm. Whether you are running new fencing, planting trees, concreting gate posts or installing vineyard infrastructure, a PTO-driven auger makes short work of what would otherwise be a full day of manual labour. Bareco supplies both the gearboxes that drive post hole diggers and the augers that do the digging — a complete solution from one Australian supplier, with freight paid to any destination in Australia.

This guide covers the Bareco Q6 and Q7 post hole digger gearboxes, all nine auger sizes from 100mm to 610mm, how to match the right gearbox to your tractor, and how to choose the right auger for the job.

Browse the Bareco post hole digger range →

How a Post Hole Digger Gearbox Works

A post hole digger gearbox does the opposite of a slasher gearbox. Where a slasher gearbox increases output speed, a post hole digger gearbox reduces it — converting the 540 RPM of a standard PTO into a slower, higher-torque output that can drive an auger through clay, compacted ground and rocky soils without stalling.

This speed reduction is the critical spec. A higher reduction ratio means more torque at the auger head, which matters on difficult ground. The Q6 has a 3.18:1 ratio and the Q7 has a 4:1 ratio — the Q7 produces more torque, suited to larger tractors tackling heavier conditions.

Both gearboxes use a standard 1-3/8" 6-spline input shaft — the universal PTO connection on most Australian tractors — and a 2" round cross-drilled output shaft that connects to standard post hole digger augers including the Bareco 9980 Series range.

Bareco Post Hole Digger Gearboxes

Q6 B4666 — 50HP Gearbox

The Q6 is the standard post hole digger gearbox for tractors in the 35HP to 50HP range — the most common tractor size on Australian farms and rural properties. The 3.18:1 reduction ratio delivers sufficient torque for most fencing and general farm post hole applications through typical Australian soils.

Specifications:

• Part number: B4666
• Power rating: 50HP
• Gear ratio: 3.18:1 reduction
• Input shaft: 1-3/8" 6-spline (standard 540 RPM PTO)
• Output shaft: 2" OD round, 1/2" cross-drilled
• Spare parts available: bearings, seals, gears
• Freight paid to any destination in Australia

Fill with EP140 gear oil before first use. Spare parts including oil seals, bearings and gears are available on request.

View the Q6 50HP Post Hole Digger Gearbox →

Q7 B5666 — 75HP Gearbox

The Q7 is built for larger tractors in the 60HP to 75HP range and for operators working in heavier conditions — dense clay, rocky soils, or large-diameter holes where the Q6 would be working at its limit. The 4:1 reduction ratio produces more torque at the auger head than the Q6, which means cleaner, faster hole cutting in difficult ground and less risk of stalling on large-diameter augers.

The Q7 is also the right choice for commercial fencing contractors, vineyard and orchard installers, and anyone running high-volume post hole work where the gearbox needs to handle sustained load across a full working day.

Specifications:

• Part number: B5666
• Power rating: 75HP
• Gear ratio: 4:1 reduction
• Input shaft: 1-3/8" 6-spline (standard 540 RPM PTO)
• Output shaft: 2" diameter round, 1/2" cross-drilled
• Spare parts available: oil seals, bearings, gears
• Freight paid to any destination in Australia

View the Q7 75HP Post Hole Digger Gearbox →

Which Gearbox Do You Need?

If your tractor sits between these ratings, lean toward the Q7 — the additional torque from the 4:1 ratio gives more headroom on difficult ground and protects the gearbox under sustained load.

Bareco Post Hole Digger Augers

Bareco 9980 Series augers are available in nine diameters from 100mm to 610mm. All augers feature a 50mm internal diameter drive tube for connection to the Q6 or Q7 gearbox output shaft, clockwise rotation, and replaceable cutting teeth included. Replacement cutters and screws are available separately for ongoing maintenance.

The augers are compatible with the Bareco Q6 gearbox and most other standard post hole digger units with a 2" round output shaft — making them a practical replacement or additional diameter for existing post hole digger setups.

Auger Size Guide

As a general rule: match the auger diameter to the post you are installing. For a round timber post, the hole should be 50–75mm larger than the post diameter to allow for backfill compaction. For concrete footings, size the hole to the footing specification.

Safety Shield

The AS8209 auger safety shield is available to suit the 228mm and 300mm augers. The shield covers the area where the auger meets the gearbox output shaft — a pinch point during operation. The B4665 bolt and nut kit is required to fit the shield. For commercial operators and anyone working under WHS obligations, a safety shield on an exposed rotating auger connection is standard practice.

What You Need for a Complete Setup

A tractor-mounted post hole digger requires four components. Bareco supplies all of them:

1. Post hole digger gearbox — Q6 (50HP) or Q7 (75HP)
2. PTO drive shaft — to connect the tractor PTO to the gearbox input. See the Bareco PTO shafts range for sizing.
3. Auger — in the diameter suited to your post or footing size
4. Safety shield — AS8209, suits 228mm and 300mm augers

If you already have a post hole digger gearbox from another supplier, the Bareco augers will connect to any unit with a standard 2" round cross-drilled output shaft.

Maintenance

Both gearboxes require EP140 gear oil before first use. Check the oil level at the start of each season and inspect the input and output shaft seals for leaks. Replacement seals, bearings and gear sets are available on request. Replace cutting teeth when wear causes the auger to labour or produce unclean holes — replacement cutters and screws are available separately for all nine auger sizes.

Browse the Bareco post hole digger range →  |  Full Bareco parts range →

Frequently Asked Questions

What is the difference between the Q6 and Q7 post hole digger gearbox?

The Q6 (B4666) is rated to 50HP with a 3.18:1 gear reduction. The Q7 (B5666) is rated to 75HP with a 4:1 reduction. The Q7 produces more torque at the auger head, making it the better choice for larger tractors, heavier soils, large-diameter augers, or commercial-volume post hole work. If your tractor is between 50HP and 75HP, the Q7 is the safer choice.

Will Bareco augers fit my existing post hole digger?

Bareco 9980 Series augers have a 50mm internal drive tube and suit the Q6 gearbox output shaft and most other standard post hole digger units with a 2" round cross-drilled output. Check your existing gearbox output shaft diameter and connection type before ordering. Call 1300 027 886 if you are unsure.

What auger size do I need for standard rural fencing posts?

For most rural fencing applications using round timber posts in the 100–150mm diameter range, the B8007 (203mm) or B8009 (228mm) auger is the right size — large enough to allow backfill compaction around the post without being unnecessarily wide. For strainer posts and gate posts, move up to the B8012 (300mm) or B8015 (380mm).

Do the gearboxes include freight?

Yes. Both the Q6 and Q7 post hole digger gearboxes include freight paid to any destination in Australia. Augers ship at standard freight rates.

What gear oil do the Bareco post hole digger gearboxes use?

Both the Q6 and Q7 require EP140 gear oil. Fill before first use and check the level at the start of each season. Spare parts including oil seals, bearings and gears are available on request through Uniclamp.