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  • 5 fisher street laporte, in 46350
  • 800-348-8809




Power Source 4 Cylinder 125HP (Tier 4)
Horsepower 125 HP
Max Spindle Torque HIGH: 22,550 ft. lbs. (30,574 Nm), LOW: 9,097 ft. lbs. (12,333 Nm)
Spindle Bore 3.5" (89 mm)
Push & Retract Force Down : 21,450 lbs (95kN), Up : 32,515 lbs (145kN)
Rotary Box 2 Speed All Gear Drive
Clutch 13" Clutch
Transmission Helical Gear 6 Speed Transmission
Drilling Type All Purpose

Heavy-duty drill rig for soil and rock exploration using augers, rotary tools or core drilling tools.

Rated from 200 ft. (61m) to 350 ft. (107 m) depth with hollow stem or continuous flight augers up to 19” (483 mm) hole size.

Rated to 2000 linear feet (610 m) of core drilling using N series tools.


  • Mast (several sizes available)
  • Cathead
  • Hydraulic Hoist
  • Slide Base (In/Out)
  • Side Slide Base
  • Leveling Jacks
  • Drill Platform
  • Water Tank
  • Rod Rack
  • Auger Rack
  • Tool Boxes
  • Drillers Step
  • Hydraulic Chuck
  • Water Pump
  • Fluted Kelly (only for HT option)
  • High Rise Pump Mount
  • Hydraulic Rod Holder & Breakout Wrench
  • 140lb. Automatic SPT Hammer System

Heavy-duty drill rig for soil and rock exploration using augers, rotary tools or core drilling tools.

Rated from 200 ft. (61m) to 350 ft. (107 m) depth with hollow stem or continuous flight augers up to 19” (483 mm) hole size.

Rated to 2000 linear feet (610 m) of core drilling using N series tools.

Power Unit

The D-120 unit is powered by a 125 HP, 4-cylinder turbo charged Tier 4 diesel engine.

Frame & Base

The drill frame is a weldment, constructed of heavy wall rectangular steel tubing, with sufficient strength and rigidity for heavy duty use.

Clutch & Transmission

Clutch – 13 inch (330 mm) automotive type.

Transmission – Heavy duty helical gear transmission with 5– forward and 1 – reverse gears. New 2024+ models have 6 speed transmissions.

Optional Cathead is driven hydraulically.

Right Angle Drive

The right angle drive is a heavy-duty gearbox running in oil.

Rotary Box

The drill head utilizes a 2-speed all gear drive with 8620 heat treated gears.  Tapered roller bearings, running in gear oil, are used.  A chuck is available (optional) for all standard size rods and casing.

  • Spindle Bore : 3.5″ (89mm)
  • Spindle Travel : 68″ (1727mm)
  • Thrust @ 2300 PSI
    • UP: 32,515 lbs. (145 kN)
    • DOWN: 21,450 lbs. (95 kN)
  • Max Feed Rate:
    • UP : FPM 41 (13 m/min)
    • DOWN : FPM 74 (23 m/min)
    • UP Rapid Retract : 64 FPM (20 m/min)
  • Max Gross Spindle Torque:
    • 1st Gear Low Range:
      • 9,097 ft.lbs. (12,333 Nm)
    • 1st Gear High Range
      • 22,550 ft.lbs. (30,574 Nm)
Hydraulic System

On the D-120 unit, oil is supplied by a heavy-duty gear type two-section pump rated at 19 GPM (72 L/min) and 28 GPM (106 L/min) at 2400 RPM.  Maximum operating pressure is 2300 PSI (15,513 k Pa).  The pump is gear driven from the engine accessory drive.

Hydraulic valves are stock sectional body directional control valves with relief. All controls are conveniently located on a single console for ease of operation.

Auger Adapter

A heavy duty universal joint is provided for ease in hook-up and adjusting for misalignment.  All components are sized to withstand torque and axial loads encountered under most drilling conditions.  The 6-1/4” (159mm) I.D. HSA box is standard but other sizes are available.


The mast is available in 3 standard lengths for 21 ft, and 24 Ft, and 29 ft pulls. The maximum mast height is limited by the type of carrier. The mast is pivoted on the drill frame permitting operation of the drill with the mast horizontal. Quick disconnect is standard for both lengths. Sheaves are provided for 1″(25.4mm) manila rope, 3/8″(9.5mm) and 1/2″(12.7mm) wire rope. The sheaves are 8″(203mm) diameter to reduce fatigue in the wire rope.


The cathead is mechanically driven from the drill transmission. The PTO provides 1 speed forward and 1 reverse. Drum is 8″(203mm) diameter and 6″(152mm) long with generously sized flanges.

The newly improved 2023+ cathead winches are hydraulically driven. The drum can be spun both clockwise and counterclockwise. Drum is 6″ diameter and 6″(152mm) long with generously sized flanges.

  • Line Pull : 5,000#(2270 kg) +
  • Speed : 500 ft./min. (153m/min) +

The cathead is mounted to the right rear of the drill and is perpendicular to the long axis of the drill frame.

Hydraulic Hoist

Various capacity options are available, Hydraulic hoists utilize a worm gear drive with a sealed case. Gears and tapered roller bearings run in oil. Housing and drum are designed to prevent fouling of the cable. The controls are mounted on the operators console. Hoists are provided with a safety brake to prevent roll-back.

Slide Base

A hydraulically operated sliding base provides 20 in(508mm) of travel to provide clearance for hoisting tools. The sliding base can be mounted on any flat surface of adequate size.

Side Shifting Base

Hydraulically operated, side to side provides approximately 6″(152mm) of motion left and right of center.

Leveling Jacks

Jacks are available for rear and front mounting. 4″(102mm) bore cylinders are enclosed within telescoping steel tubes for increased durability and stability. Each jack is provided with a pivoted foot pad with a non-slip surface. Standard stroke is 36″(915mm)

Drill Platform

Dimensions vary with the truck and carrier size. Welded construction consists of structural steel and deck plates. Running lights are included.

D-120 truck lengths vary with chosen options. A standard requirement is a tandem axle truck for the application. Contact us for more information on truck dimensional requirements.

Water Tank

250 gallon (946 l) or 500 gallon (1892 l) welded steel water tanks mount at the front of the drill platform. Other tanks are available on request.

Rod Rack

Above deck rod rack and underbody rod rack are standard with drill platform. Optional rod storage under the water tank is also available.

Auger Rack

Above deck auger rack is standard with drill platform. Underbody fixed, hinged, or hydraulic auger racks are available.

Tool Boxes

Tool boxes are available for above or below deck mounting in several sizes.

Drillers Step

Heavy duty drillers step can be mounted on the right and/or left side of the drill platform. The step folds up for storage.

Hydraulic Chuck

Hydraulic chuck mounts to top of spindle with jaws available through 3-1/2″(89mm)

Water Pump

Pump is frame or deck mounted and driven from the rigs’ hydraulic system

  • FMC L1122 (435) With Variable Speed
  • Monyo 3L8 With Variable Speed
  • SP50 Hose Pump With Variable Speed

Other water pumps available on request.

Fluted Kelly

A fluted kelly is available for the HT option.

Hydraulic Rod Holder & Breakout Wrench

This device is capable of holding up to 8″(203mm) O.D. drill rods or casing. It slides on and off the hole and also moves side to side. The device stores easily under the rig. A hydraulic breakout wrench is provided.

140lb. Automatic SPT Hammer System

The Diedrich automatic SPT hammer system hydraulically lifts a 140 lb.(63.5kg) drive weight and completely releases the weight for a 30 in.(762mm) free fall. The drive weight does not have a cable or rope attached that may impede its fall. The hammer can be operated at a rate of up to 46-48 blows per minute. The tolerance of the fall height is plus or minus 3/8 inch(9.5mm). The hammer mounts on the guide tube so that it can be hydraulically raised and lowered and easily moved to the on hole driving position. The hammer can also be operated while suspended from a winch cable. The hammer driving force is transmitted only to the anvil and rods and the hammer allows for up to 24 inches(610mm) of driving without movement of the hammer body. The drive weight, lifting mechanism, and anvil impact surface are enclosed to provide optimum safety.

Morooka Mounted

Diedrich Drill D-120 Drill Rig

Truck Mounted

Diedrich Drill D-120 Drill Rig

Track Mounted

Diedrich Drill D-120 Drill Rig

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