Underground Singapore 2011
Figure 4. BAUER BG 42 with two rotary drives
The system worked very efficiently, achieving high installation rates. The main disadvantage was the costly installation of the second rotary drive with additional hydraulics and the difficulty of converting back to conventional drilling modes in terms of time and cost. 6 "CASED CFA" SYSTEM WITH TORQUE MULTIPLIER BTM In view of this further developments of the drilling method were investigated. The result was the introduction of a torque multiplier in combination with a spoil discharge chute system. The Bauer Torque Multiplier (BTM) is a mechanical unit attached to the cardanic joint below the rotary drive. The ratio is fixed at 1:2, so that the BTM doubles the incoming torque, halves the speed and inverts the direction of rotation of the casing. The resultant has to be limited to remain within the structural capacity of the mast of the drilling rig. The incoming torque from the rotary drive needs to be limited to suit the specific application and the bearing capacity of the mast.
Figure 5. BAUER BG 36 with torque multiplier BTM 400 and spoil discharge chute system
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