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Unformatted text preview: ed by gathering arms and
loaded on the conveyor. The cutting head consists of five to seven cutting chains with
picks which runs in guides all around the ripper bar (fig. 10.2(a)). The ripper bar is hinged
at the rear end, which permits the front end to raise or lower. The chains are driven by
electric motors. The whole unit i.e. the cutting chains, the motors and the conveyors
can be telescoped forward to cut the rock/coal.
To give a cut, the machine is positioned in the center of the face with cutting head
retracted. The machine’s cutting head is swung to one side of the face and lowered
down to the floor. With the chain in motion the ripper bar is hydraulically pushed © 2005 by Taylor & Francis Group, LLC TUNNELING BY ROADHEADERS AND IMPACT HAMMERS 241 forward in the rock/coal (usually 460 mm). After it has been fully advanced the ripper
bar is gradually raised until it reaches up to the roof and this completes one strip. With
a meter wide ripper bar, five such slices are required to complete a 5 m wide gallery
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This document was uploaded on 02/12/2014.
- Spring '14