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Robotics

DTH

1955ActivePublished: 28 October 2026Updated: 28 October 2026Published
Key innovation
Placing the pneumatic percussive hammer directly behind the bit at the bottom of the hole, so impact energy reaches the rock with minimal loss regardless of hole depth.
Category
Robotics
Abstraction level
Pattern
Operation level
Robot control
Use cases
Foundation drillingPre-drilling for piles (e.g. solar pile installation)Mining and quarryingWater wellsGeothermal boreholesBlast-hole drilling in hard rock

How it works

The hammer is fully fluid-actuated and consists of two moving parts: a valve that controls the flow and a piston that strikes an impact surface directly linked to the bit. The hammer body guides the bit, giving a straight and stable hole. The drill pipes provide rotation and feed and deliver the working fluid, which after actuating the hammer flushes the cuttings to the surface. Hammers are classified by actuation fluid: air hammers (compressed air; typically limited to holes shallower than about 200 m), water hammers (deeper holes) and drilling-mud hammers.

Problem solved

In top-hammer drilling, impact energy must travel through an ever-longer string of rods, which causes large energy losses and hole deviation in deeper holes. DTH solves this by delivering the impact at the bottom of the hole, directly behind the bit.

Components

Down-the-hole hammerFluid-actuated percussion mechanism operating at the bottom of the hole.

Fully fluid-actuated assembly containing a valve and piston; delivers impact directly behind the bit.

PistonStrikes the impact surface linked to the bit.

Moving part of the hammer that converts working-fluid pressure into impact energy.

ValveControls the flow of the working fluid through the hammer cycle.

The hammer's second moving part, distributing the flow that drives the piston.

Drill bitRock-cutting end struck by the piston.

Bit linked to the impact surface, typically fitted with tungsten-carbide inserts.

Drill pipes / drill stringTransmit rotation and feed and deliver the working fluid.

Added successively behind the hammer as the hole deepens.

Implementation

Implementation pitfalls
Limited depth of air hammersMedium

Compressed-air hammers are typically limited to holes shallower than about 200 m.

Fix:For deeper holes, use water hammers or drilling-mud hammers.

Evolution

1844
First pneumatic rock drilling

A pneumatic tool is first thought to have been used for rock drilling in 1844.

1955
Independent invention of the DTH method (mid-1950s)
Inflection point

The method was invented independently by Stenuick Frères (Belgium) and Ingersoll Rand (USA) in the mid-1950s.

Hyperparameters (configurable axes)

Actuation fluidCritical

Fluid that actuates the hammer: air, water or drilling mud.

Sprężone powietrzeAir hammers, typically holes < ~200 m.
WodaWater hammers, deeper holes.
Płuczka wiertniczaMud hammers, e.g. deep geothermal drilling.
Hole depthHigh

Achievable depth depends on hammer type and working fluid.

Bit diameterMedium

Diameter of the drilled hole, matched to the application.