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PDT8 Earth Drill

40-150 lpm - 2 Speed

PDT8 Earth Drill

40-150 lpm - 2 Speed

It’s like owning 2 drives in 1

The PD8 Two Speed builds on the proven performance of the single-speed PD8, delivering enhanced flexibility and torque in a compact design. Engineered for machines up to 8 tonnes, it offers a significant torque increase over the PD6 Two Speed, while retaining the same hydraulic specs—handling flows up to 75 lpm and accommodating 25 kW of continuous hydraulic power. A larger gearbox reduction boosts output torque, with only a minor increase in physical size.

With two-speed functionality, it’s like having two drives in one: use high-speed mode for fast spoil removal and efficient bore cleaning, then switch to high-torque mode to power through harder ground or drive larger-diameter augers.

This versatility allows operators to run a high-torque drive on a smaller host machine—without compromising speed when clearing holes or flicking spoil. Built for both light and heavy-duty tasks, the PD8 Two Speed is ideal for operators demanding performance, efficiency, and reliability from a compact drive. Whether it’s fencing, tree planting, or foundation work, the PD8 two speed is designed to help you get more done with your mini excavator or skid steer.

Speeds

2 Speed

Halo Alignment System

Optional / Retrofit Available

Machine Suitability

Skid Steers, Excavators

Ideal Application

Foundation Drilling, Piling & Drilling Contractor, Commercial & Residential Construction, Infrastructure & Civil Works, Renewable Energy, Utilities, Mining

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FAQs

Features

Two-Speed Drive. Get the performance of two drives in one. Use high-speed mode for fast spoil removal and efficient bore cleaning, then switch to high-torque mode to drill through tough ground or run larger-diameter augers. This flexibility lets you run a high-torque drive on a smaller machine—without sacrificing speed.

Wider Range of Applications
Handle both small and large piling jobs with one drive unit—use high speed for quick drilling of smaller diameters and switch to high torque for larger diameters and tougher tasks, all without changing drives. This dual-speed flexibility maximizes efficiency and versatility on site.

Lifetime Shaft Pull-out Warranty. Equipped with in-house designed, & manufactured shaft locking nut, this system is guaranteed to prevent shaft pull-out.

Built Tough. Digga gearboxes are built for long-lasting, dependable performance, backed by over forty years of trusted use. Precision-machined gears ensure outstanding reliability and a strong return on investment.

Halo: The perfect drilling partner

Halo is the ultimate solution for efficient and precise drilling; designed to save time, reduce costs, and ensure unmatched accuracy. By eliminating the need for a spotter, Halo allows you to reallocate onsite labour to other tasks, or operate autonomously with ease.

Its intuitive operation ensures impressive results, delivering more accurate boreholes and minimising costly hole oversizing. With Halo, you can achieve exceptional returns on your investment and maximise project efficiency. Halo is an indispensable tool for modern drilling operations.

Digga HALO auger drive hero graphic.

Specifications

Designed for machines up to 8 tonnes, the PD8 Two Speed delivers higher torque than the PD6 with the same hydraulic specs—handling up to 75 lpm and 25 kW combined Hydraulic power. A larger gearbox reduction boosts torque output with only a slight size increase. Two-speed operation lets you switch between high-speed for spoil clearance and high-torque for drilling, making it ideal for larger augers and tougher ground—without compromising performance on smaller machines.

Specifications
Machine Size SuitabilityUp to 8 tonnes
Recommended Flow20-75 lpm
Maximum Torque5,918 Nm
Pressure ValveOptional
Recommended Auger6 Series
Maximum Auger Diameter (Earth)1000 mm
Maximum Auger Diameter (Clay / Shale)900 mm
Maximum Auger Diameter (Fracturable Rock)900 mm
Build Information
Overall Length922 mm
Diameter290 mm
Weight (Without Frame / Hitch)130 kg
Standard Output Shaft75 mm Square
Energy Control ValveNot Applicable
Case Drain RecommendedYes
Maximum Pressure205 bar
Maximum Flow75 lpm
Maximum Power (Combined Flow at Pressure) 25 kW (34 hp)
Swing ControlOptional
DiggalignOptional
Halo AvailableOptional
auger drives specs PDT8 line drawing

Torque / Speed Charts

Torque chart (Nm)

Pressure (bar)Low (Nm)High (Nm)
902,5461,247
1002,8281,385
1103,1111,524
1203,3941,662
1303,6771,801
1403,9601,939
1504,2432,078
1604,5252,217
1704,8082,355
1805,0912,494
1905,3742,632
2005,6572,771

Speed chart (RPM)

Speed (lpm)Low (RPM)High (RPM)
20 1118
251423
301728
352032
402336
452541
502945
553150
603454
653759
703963
754269

Output speed and torque specifications are theoretical. Speed and torque outputs are dependent on overall system efficiencies associated with the prime mover's hydraulic system. This information should be used for comparative purposes only. When determining criteria, application-specific information is required. please contact DIGGA.

Compatible Augers

A6 Auger

Bladed Teeth
Auger specs A6 line drawing.

RC6 Auger

Tapered Teeth
Auger specs RC6 line drawing.

DR6 Auger

Rotating Rock Picks
Auger specs DR6 line drawing.

Extensions

XT75 (Inner) & XO75 (Outer) Auger extensions

Digga’s versatile drilling extension range is the ultimate in quality and cost effectiveness. Our extensions are manufactured in-house by Digga using only the highest-grade materials and strictest quality control. The XT/XO range of extensions is suited for machines up to 6 tonnes and is available in a variety of lengths – In inner and outer configurations. By pairing an inner and outer extension, you can double (or more) your drilling depth ability. For custom solutions, feel free to consult one of our sales specialists.

An added bonus of using inner and outer Digga extensions is that you can conveniently store the inner extension inside the outer extension, to save valuable space on your truck or trailer.

Extension Specifications

Maximum Torque7,200 Nm
Standard Hub75 mm Square
Body (Outer)Heavy Duty Tube - Fixed Length
Body (Std Inner) 75 mm Square RHS - Variable Length
Body (HD Inner) Solid Bar - Variable Length
Lengths1000 mm / 1500 mm / 2000 mm / 2500 mm

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LEARN MORE ABOUT EARTH DRILLS

From understanding the different types of earth drills available, to learning about components and maintenance, we hope you find this information helpful.

FREQUENTLY ASKED QUESTIONS

What earth drill best suits my machine?

General rule of thumb would be that your machine weight matches the model code of the earth drill.

i.e. 2 Tonne Machine – PDX2, 3 Tonne – PD3, 5 Tonne – PD5, etc., etc...

Your application and expectation would be the next governing factor.

i.e. For a 5 Tonne machine

The standard model reference of PD5 would best suit augering in general conditions of soil, clay, shale up to approx. 900mm.

Should your main drilling requirement only be for softer ground conditions with smaller diameter augers, e.g. sand and soil with augers up to 600mm dia., then you may consider stepping down a model size to a PD4-5, (-5 denotes 75mm Square Output Shaft to match the recommended Type 6 Auger Bits). This step down in model will give you more auger speed while still maintaining enough power to cope with the down-pressure of the 5 Tonne machine.

Likewise, if your application requires larger dia. holes or harder condition, i.e. rock, then stepping up a model or two, PD6 or PD7 may best suit these applications.

What is the biggest earth drill I can put on my machine?

There is a several factors that are at play when suiting up “The Biggest earth drill” consideration needs to be given to:

  • Lift capacity of the host machine: should the weight of the drill exceed the SWL (safe Working Load) of the host machine then the drive should not be fitted.
  • Ground clearance: Careful consideration needs to be given to insure there is ample ground clearance under the pickup of the host machine when both the drive and drilling tool or Screw Pile are fitted.
  • Application Overview: When selecting the largest drive, it's essential to consider both the desired outcome and the specific job requirements. These factors will significantly influence the choice of the appropriate drill.
What is kW and why does it Matter?

Every hydraulic motor fixed to a planetary gearbox has a listed maximum power (kW) rating. Exceeding this rating will cause motor damage and failure.

Power is created by combining pressure and flow. You may increase pressure while reducing flow, or increase flow while reducing pressure – maximise both simultaneously may exceed the motor's safe operating limits. The kW Power can be calculated with the following formula (kW) = Flow (litres/minute) × Pressure (bar) ÷ 600

Operating outside the rated kW will cause:

  • Excessive heat buildup, degrading hydraulic fluid
  • Internal seal and shaft damage
  • Motor seizure and failure
  • Costly downtime and replacement
What happens if put the wrong drive on my machine?

If you install the wrong planetary earth drill on your machine, several issues could arise, potentially affecting performance, safety, and the longevity of both the drive and the machine:

  1. Incorrect Torque and Speed: The earth drill may not be suited to the hydraulic flow and pressure of your machine. This can result in too much or too little torque, either leading to inefficient digging or overstressing the drive components leading to frailer.
  2. Reduced Efficiency: The wrong drill might not be optimized for your specific drilling conditions, causing slower digging and increased wear on the auger teeth and pilot, leading to more frequent maintenance.
  3. Hydraulic System Strain: Using an incompatible drive could place excessive strain on your machine's hydraulic system, potentially causing overheating or damage to pumps, hoses, and other components.
  4. Poor Performance: If theearth drill is mismatched, it may not provide the required torque or rotational speed for your ground conditions, leading to subpar hole performance, especially in difficult ground.
  5. Increased Wear and Tear: An incorrect drive can accelerate wear on both the drill and the auger, leading to more frequent breakdowns or even failure, which can be costly and time-consuming to repair.
  6. Safety Hazards: A mismatched drive may cause unexpected behaviour, such as uncontrolled movements or failure under load, which could create a safety risk to operators, bystanders and equipment.

For optimal performance and safety, it's crucial to match the earth drill to your machine's specifications and the ground conditions you are working in.

What are the advantages of a 2-speed earth drill?

A 2-speed drill offers enhanced versatility and efficiency for drilling applications by providing two selectable speed ranges:

  1. High Torque (Low Speed): This setting is ideal for drilling through hard, compacted ground, clay, or rock. It delivers maximum torque, allowing the auger to cut through tougher materials with greater force, though at a slower speed.
  2. High Speed (Low Torque): This setting is suited for softer soils, such as sand or loam, where high torque isn't necessary. It allows for faster drilling, increasing productivity by completing holes more quickly in easier ground conditions.

Benefits of a 2-Speed Drive:

  • Versatility: Allows you to switch between speed and torque depending on the ground conditions, making it suitable for a wide variety of drilling environments.
  • Efficiency: Saves time and wear on equipment by using the appropriate speed and torque for each specific task.
  • Enhanced Versatility and Performance: Engineered to handle both hard and soft soils, this design allows for the integration of a larger reduction gearbox, delivering increased torque without compromising speed. Enjoy the performance benefits of two earth drills in one, eliminating the need for equipment changes and significantly boosting overall job efficiency.

In short, a 2-speed drill offers greater diversity, control, and adaptability, ensuring optimal performance and productivity across different drilling conditions.

Can one earth drill fit both my machines?

It is possible to get an earth drill that can be used with two different size machines, but it will depend on the specific earth drill and the machines you have. If your two machines are close in size, for example a 5t and 10t or 15t and 20t but the drill must be suited to the larger machine, it is not feasible should you have a 3t and 20t machine as the physical size of the drive for the 20t machine is far too large for the 3t machine and the performance output would be inadequate to perform normal drilling.

Some earth drills are designed to be used with a range of different machines and may come with adaptors or other attachments that allow them to be used with different sizes of equipment. However, it's important to check the specifications of the earth drill and the machines you must ensure that they are compatible.

Additionally, it's important to consider the power and torque of the machines, and the size and weight of the earth drill. A larger or heavier earth drill may require a more powerful machine to operate, and a smaller machine may not be able to handle the weight and torque of the earth drill.

It's important to consult with the manufacturer or a professional before deciding, and to check the compatibility and capacity of your machines with the earth drill you want to use.

The other option that is idea for this scenario of running one drive two machines is a two-speed drive (see 2- Speed high flow & 2-Speed STD flow).

Will my 1.0Tonne machine dill a 600mm Dia. hole in solid rock?

In general, we would have to say NO - For the following reasons:

  1. Without knowing the grade of rock, e.g. for sandstone there are 5 grades, 1 – being soft and weathered, classed as drillable, and 5 – being extremely hard and classed as un-drillable.
  2. The physical downforce of your machine will not carry enough weight to functionally drill this diametre. hole in rock.
What is the difference between a PD5, PD6 & PD7?

There are several differences between a PD5 & PD6, PD7

The main is the amount of torque outputted by each individual unit PD5 Max. Nominal Torque @ 240bar Pressure is 5000 Nm., PD6 – 5,500 Nm & PD7 – 6,000 nm.

With each increment in increase of torque you have an equal decrease in output shaft speed when inputting the same amount of flow (Lpm or Gpm).

Additional differences between the PD5 and the PD6 & PD7 is the gearset of a PD5 has a Series 2 Gearset where the PD6 & PD7 have a series 4. This difference is in the thickness of the gearsets in each. These differences are there to cope with the increasing weight of the parent machine and for the increase in torque capabilities.

Also, there is a marked difference in the bearings size of the PD6 & 7 over the PD5. The increase in size of the bearings in the PD6 & 7 is to cope with the increase in weight from the parent/host machine.

What is better, Round, Square or Hex Shaft?

Depending on the torque output of the drive unit we would recommend a square or hexagonal shaft for all drives over 4,500 Nm. For drives under this torque rating a 65mm Rnd as standard relies on the auger pin to bare the rotational load of the drive unit. This pin is rated to 10Knm but with our safety factor we like to step up to Sq or hex for torques higher. By using sq. or hex we are supporting the rotational load of the drive on the four side of the square or the 6 sides of the hex.

Why does my earth drill need servicing?

The gearbox of earth drills sit in their own bath of oil. The gearbox is not lubricated by the machines hydraulic oil, as a result the oil needs regular changes similar to your car.

Service intervals are outlined in the operator’s manual provided with all Digga attachments. The recommended intervals depend on the intensity of use, ranging from occasional to extreme. For best practices, consult the manual to determine the appropriate maintenance schedule based on your specific usage.

Regular servicing is essential to maintain performance and extend the life of your equipment as well as your warranty.

What oil do I use in the gearbox?

Depending upon the earth drill model being used and its application with determine the type of oil to be used, but in all drive, we recommend using and “EP” (Extreme Pressure) oil this will ensure longevity of your gearbox. Typically, your drills will come from factory filled with:

  • ISO EP320 Mineral Oil ... for PDD to PD50 including 2 Speed drives
  • ISO EP320 Synthetic oil ... for SD, MD, UD, XD drives

Note : if unsure please contact the Digga Service department for guidance

Can I fit HALO on a competitor's earth drill?

You can't use the Digga HALO system on non-Digga earth drills because the HALO system is specifically designed and engineered to suit Digga earth drills.

Here are some key reasons:

  • Compatibility: The HALO alignment system is built to integrate seamlessly with Digga drills, ensuring correct fitment and performance. Competitor earth drills may have different dimensions, or operational requirements that aren't compatible with the HALO system.
  • Calibration: HALO uses 6 sensors to provide real-time feedback on the auger’s angle for precise drilling. These sensors are calibrated to work specifically with Digga’s drills and control systems.
  • Warranty and Support: Digga products, including the HALO system, are covered under specific warranties when used with compatible Digga components. Installing HALO on a non-Digga drive will void warranties,

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