A down-the-hole drill, usually called DTH by most professionals, is basically a jackhammer screwed on the bottom of a drill string. The fast hammer action breaks hard rock into small cuttings and dust that are evacuated by a fluid (air, water or drilling mud). The DTH hammer is one of the fastest ways to drill hard rock. The system is thought to have been invented independently by Stenuick. Origin of the nameDTH is short for “down-the-hole”. Since the DTH method was originally developed to drill large-diameter holes downwards in surface-drilling applications, its name originated from the fact that the percussion mechanis. .
In DTH drilling, the percussion mechanism – commonly called the hammer – is located directly above the drill bit. The drill pipes transmit the necessary feed force and rotation to the hammer and the bit, along with the flui. .
A is first thought to have been used for rock drilling in 1844. Many quarries used hand held tools that required the driller to suspend himself from a rope over the quarry face in order to place the drill hole in.
[pdf] with Blast Hole Coupling and High Speed Water Swivel .
The chuck is accurately machined to assure perfect alignment. The jaws are held by two large, Allen set screws with countersunk heads in chuck body to make it impossible for them to catch the operator’s clothing while rotating. Successive pairs of. .
Exploded view showing method of jacking rear end plate out of motor housing for changing rotor blades .
The reversible air motor greatly speeds blast hole drilling by allowing rapid unscrewing of rod joints, after breaking joint with a wrench, and allowing for rapidly moving the chuck or blast hole coupling into drilling position. High bit speeds available where. .
The motor consists of a cylinder in which a rotor is mounted eccentrically, six slots in the rotor hold six laminated, phenolic blades which move in and out against the cylinder wall as the rotor revolves. These blades and the rotor are the only rotating parts. Ball bearings,.
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