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PDT4HF Earth Drill

50-117 lpm - 2 Speed

PDT4HF Earth Drill

50-117 lpm - 2 Speed

Two Drives in One

The Digga PDT4HF Two Speed Auger Drive delivers high torque and speed for demanding jobs. It’s designed for large-frame, high-flow skid steer or track loaders, excavators, and truck cranes up to 6 tonnes. The motor and gearbox combination suits cranes with higher pressure and lower flow, supporting up to 117 lpm and accepting 60 kW of continuous hydraulic power.

As Digga’s entry-level High-Flow Two Speed model, the PDT4HF provides a heavy-duty, high-performance solution for machines needing strong torque or fast operation with smaller augers. A switch toggles between two modes:

  • High-speed, low-torque: For small-diameter augering, rapid spoil removal, and hole clean-out.
  • Low-speed, high-torque: For larger augers, deeper holes, and tough ground.

This dual-speed system offers greater control, efficiency, and flexibility, allowing a larger reduction gearbox on smaller machines without losing drilling speed. High speed is available on demand, while torque is preserved for challenging conditions.

Speeds

2 Speed

Halo Alignment System

Optional / Retrofit Available

Machine Suitability

High Flow Skid Steers, Excavators, Backhoes

Ideal Application

Foundation drilling, fencing contractor, farming, landscaping, utilities

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Specifications

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FAQs

Features

Wider Range Of Applications. Install small and larger piles with just one drive unit, with the best of both worlds: High speed when you need it, and high torque allowing you to take on that slightly larger job with the same equipment.

Compact & Powerful. This drive is both incredibly compact and remarkably powerful, delivering exceptional performance and impressive output torque for its size, ensuring optimal efficiency and reliability for demanding tasks.

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 to last, renowned for their quality, dependability, and a legacy of trusted performance spanning over four decades. Crafted with precision-machined gears, delivering outstanding performance, reliability, and an excellent 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

The Digga PDT4HF is a two-in-one earth drill offering both high-speed and high-torque modes. Designed for high-flow skid steers, track loaders, and excavators or cranes up to 6 tonnes, it handles up to 117 lpm flow and delivers 60 kW continuous hydraulic power. It’s also suitable for large but hydraulically limited machines, such as cranes with high pressure and low flow.

Operators can switch between modes on demand: use high-speed for small augers, spoil removal, and clean-out; switch to low-speed for maximum torque in tough ground or larger holes. The PDT4HF features a two-speed orbital motor, precision valve system, and robust planetary gearbox for reliable performance and durability across many applications.

Specifications
Machine Size SuitabilityUp to 6 tonnes
Recommended Flow50-117 lpm
Maximum Torque4708 Nm
Pressure ValveIncluded
Recommended Auger6 Series
Maximum Auger Diameter (Earth)1000 mm
Maximum Auger Diameter (Clay / Shale)750 mm
Maximum Auger Diameter (Fracturable Rock)750 mm
Build Information
Overall Length829.5 mm
Diameter340 mm
Weight (Without Frame / Hitch)135 kg
Standard Output Shaft75 mm Square
Energy Control ValveOptional
Case Drain RecommendedYes
Maximum Pressure240 bar at 117 lpm
Maximum Flow117 lpm at 240 bar
Maximum Power60 kW (80 hp)
Swing ControlOptional
DiggalignOptional
Halo AvailableOptional

Torque / Speed Charts

Torque chart (Nm)

Pressure (Nm)High Torque Output (Low Speed)Low Torque Output (High Speed)
901,7561,167
1001,9511,297
1102,1461,426
1202,3411,556
1302,5361,686
1402,7311,815
1502,9271,945
1603,1222,075
1703,3172,204
1803,5122,334
1903,7072,464
2003,9022,593

Speed chart (RPM)

Flow (lpm)Low Speed Output (High Torque)High Speed Output (Low Torque)
403350
504162
604974
705787
806599
9074112
10082124
11090136
12098149

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 Standard Duty Drilling Extensions are a reliable solution for increasing your drilling depth. Designed to couple directly the auger drive hub and gearbox output shaft , they’re available in a range of lengths to suit various applications. The Standard Series comes in both fixed outer extensions and a versatile telescopic system—where an inner extension slides into a matching outer extension. This allows for easier transport and flexible depth adjustment with multiple length options.

If the hole depth exceeds the lift height of the host machine, consider the XO75HD or XT75HD range of extensions as they feature integrated eyelets that allow the extension or auger to be safely suspended within the hole. This enables operators to add or remove additional extensions as needed, allowing for significantly deeper holes to be drilled beyond the machine’s lift height capacity. All extension types are available in multiple lengths to meet your jobsite requirements.

Extension Specifications

Maximum Torque7200 Nm
Standard Hub75 mm Square
Body (Outer)Heavy Duty tube - Fixed Length
Body (Inner)75mm Sq RHS (STD Duty) or Solid Bar (H'Duty) - 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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