A ____________ consists of a coil whose diameter is about 50 mm to 100 mm.

__________________ types of equipment have a continuous flow of work turned out.

_________________ is a rotary drill and it consists of steel pipe stem on the bottom of which is attached to a roller bi…

_________________ are intended for power drilling use only, the centre point locates the bit and the flat steel on eithe…

__________________ is the process of using a drill bit in a drill to produce cylindrical holes in solid materials, such …

_____________________ bits are used when some rocks are so abrasive that steel bits have to be replaced after they have …

________________ type of excavator carries the skimmer at its lower end.

______________ rollers are also known as tamping rollers.