SOrTH BULLI AND BKLLAMBI COLLIKRIES. 195 



and is free to assume any position in the valve chamber; 

 there are no tappets, guides or other mechanical connections 

 to affect its action. The coal cutter is fixed in position and 

 held up to its work by means of a solid drawn steel tube 

 provided with a powerful jackscrew, toothed head and foot, 

 see Fig. 121, which shows a side view of the Little Hardy 

 fixed for undercutting. The machine is seated in a cone 

 cup forming part of a hinged clamp attached loosely to the 

 column. This clamp carries a worm (A), the teeth of which 

 mesh with those of a worm-wheel (B), bolted rigidly on the 

 column (C). By turning the worm handle, the coal cutter is 

 caused to move round the column, the forward movement into 

 the coal is obtained by the feed-screw (D) at the back of the 

 machine. The cutter bar (E) generally has four prongs. 

 While working, the machine is swung to right and left by 

 the worm gear, and fed forward as necessary; in this way an 

 arc-shaped channel is cut, increasing in depth and width as 

 each successive length of cutter bar is inserted in the machine. 

 As soon as the desired depth is reached, the operator works 

 in gradually decreasing sweeps on right and left hand sides, 

 until the channel is of uniform depth at every point, and per- 

 fectly square at the sides and corners, using the longer cutter 

 bars where necessary. If, after the undercutting is finished, 

 it is desired to shear or nick the coal, the machine is fixed 

 near the centre of the column and is worked by a lever (F) 

 from top to bottom, though it can be worked by the worm gear 

 if desired. The coal cutter proper weighs 1501b., and the 

 total weight of a complete apparatus is under 3cwt., includ- 

 ing column gearing, cutter-bars, air-drill, etc. The air 

 pressure should be from 451b. to GOlb. per square inch. The 

 machine can be flitted from one place to another by a man and 

 -<i boy. 



At one time the colliery was drained by a Moore hydraulic 

 pump, whereby motion was conveyed from the surface to the 

 pumps below by means of water columns caused to oscillate 

 by hydraulic rams which were steam driven. This system 

 gave place, in 1904, to an electrically driven three-throw 

 single acting pump, with Sin. cylinders and 12in. stroke, 

 on account of the greater flexibility of the electric system. 

 The pump, and a 30 h.p. induction motor for driving it, are 

 located in a chamber underground, one and a half miles from 

 daylight. The motor, which is the short circuit rotor type, 

 with compensating starter, revolves 514 times per minute, and 

 is connected with the pump by belting. The pump shaft 

 revolves 45 times per minute, and raises 18,000 gallons per 

 hour against a head of 270ft., inclusive of pipe friction. The 

 pump was designed at the mine, and manufactured by Gon- 

 inan, of Wickhani, N.S.W. 



