136 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



has a concrete floor. The roof trusses are on the queen-post 

 principle, the tie beams being of sufficient strength to be used 

 for lifting from in case of necessity. The distance from the 

 centre of the shaft to the centre of the drum is 105ft., thus 

 giving a long lead from the drum to the pit head pulleys, re- 

 ducing the side friction on the rope. 



The steel head frame over the Birthday shaft (Fig. 71) 

 was made in Nottingham, and contains 80 tons of steel lattice 

 work and plating; the main and back legs are 2ft. by 2ft., the 

 corner angles being 5in. by 5in. by fin., and straps and dia- 

 gonals 2iin. by -Jin. The front legs are also 2ft. by 2ft., but 

 their corner angles are 4in. by 4in. by fin. The foot of each 

 leg rests in a strong cast-iron shoe, set on and bolted 

 down to massive concrete pillars resting on solid rock. The 

 height to centre of pulley wheels is 70ft. Sin. above the pit's 

 mouth. The pulley wheels are 18ft. in diameter, and will be 

 placed 7ft. 3in. apart. They are made in halves, and are put 

 together with bolts at the hub; and socket, tongue, and cotter 

 at the rim. While sinking, a 15ft. diameter pulley wheel was 

 arranged so that the rope passed down the centre of the shaft. 

 The large pulley was not used in sinking, as the smaller rope 

 employed would have worn a false groove in it which would 

 have been detrimental to the first larger rope used for per- 

 manent work. The detaching girders, in case of overwinding, 

 are 56ft. 3in. above the mouth of the pit, and are made strong 

 enough to sustain a treble-decked cage, carrying six skips, 

 each holding one ton of coal. At the same height are girders 

 to support two 6ft. pulley wheels for the capstan ropes. 

 These pulleys are arranged at right angles to the sinking pul- 

 ley, one at either side, but at a lower level, and are so placed 

 that all three ropes are in line ; the capstan ropes then acted as 

 guides for the cross-head above the sinking bucket, as well as 

 supports for the bricking cradle. Four lightning conductors 

 are arranged on the top of the head frame. 



Two pairs of capstan engines are erected back to back, 

 halfway between the downcast and upcast shafts. They are 

 coupled, horizontal, direct-acting, with 14|in. diameter cylin- 

 ders, and 2ft. 6in. stroke, fitted with slide valves and link 

 motion reversing gear. The crank shaft is geared down to the 

 third motion in the ratio of 9 to 1. The third motion shaft has 

 two drums keyed to it, each being 6ft. 4Mn. in diameter by 

 5ft. 6in. wide, set 8ft. apart, centre to centre, so as to corres- 

 pond to the centre of the capstan pulleys on the head frame, 

 and reduce the fleet angle. The foundations are of concrete and 

 solid rock, and the whole is in a building of brick set in cement 

 mortar. These engines will probably be altered to serve as 

 driving engines for the endless rope system of haulage which 

 it is intended to instal later on. 



