Pneumatic Drill

NAME: Pneumatic drill

ALTERNATIVE NAME/S:

DETSAILS/DESCRIPTION:

The pneumatic drill is an engineering tool used for large-scale engineering works such as mining, tunnel boring and rock excavation. It is powered by compressed air and is usually driven by rotary vane motor: compressed air pushes on vanes and this causes a central shaft or spindle to rotate. A drill is fastened to the shaft.

Alternatively, the drill may sometimes be driven by a reciprocating piston: compressed air enters a cylinder where it expands and drives a piston which delivers a series of blows to the upper end of a tool inserted in a holder below the piston.

In modern drills of this type, the piston and drill are made of high carbon steel, the drill is held loosely at the end of the cylinder and is struck by blows from the freely moving piston.

For tunnel driving, a drifter drill is sometimes used which is mounted on a rig and mechanically fed into the substance to be drilled.

The first pneumatic drill was invented by the French engineer, <invented by> Sommeiller* to facilitate the building of a tunnel through the Alps linking France and Switzerland because the transmission of steam for power was impracticable over long distances.

Sommeiller  had developed a version of the <developed from> hydraulic ram* to drive locomotives through another tunnel he worked on and this gave him the idea for his pneumatic drill. The stroke in Sommellier’s machine was given by a piston attached to the drill. The piston was enclosed in a cylinder into which compressed air was introduced at will. The lower end of the piston was broader than its upper end, and since the pressure of air was in direct ratio to the surface upon which it acted, the forward movement of the drill was more powerful than the return movement. A rotary movement of the drill was achieved by a square rod attached to a toothwheel in the body of the piston.

In America <developed by> Westinghouse* used compressed air to power the air brake on the railroads.

ONELINER:  The pneumatic drill

OTHER CONNECTIONS: None

BIBLIOGRAPHY:

The Mont Cenis Tunnel, Its Construction and Probably Consequences, Charles J Skeet, Charing Cross, London, 1873

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