262 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



mechanical heat is added to that generated by, the electricity. 

 This lower bearing 1 being* out of sight, its lubrication is apt 

 to be neglected. At Rhondda an automatic and more readily 

 accessible lubricator has been attached. The two small studs 

 that support the lower bearing practically trail on the ground, 

 and tempt Providence to break them off by bumping against 

 obstacles, when they snap oft': then the bedplate has to be 

 tapped for larger studs, and this is repeated till the limit is 

 reached. The bedplate is cast metal of irregular thickness , 

 and the strains set up in cooling tend to cause fractures. At 

 Rhondda they have had new bedplates made of cast steel. 

 One objection in working this machine is that when putting 



Conglotn e rat e 



Coal 



Band 



Co 



Fig. 168. Section of Upper Scam, llhondda Colliery. 



in the sumping or opening cut, the cuttings are hemmed in 

 by the sides 'of the pan, so that they cannot be shovelled out. 

 This obliges the machine to plough its way in, and causes 





