PELAW MAIN COLLIERY. 34S> 



cool the air. The intercooler between the two air cylinders is 

 composed of a pipe containing copper tubes, that split the 

 air compressed in the low pressure cylinder into thin streams, 

 which are cooled by circulating water. By cooling the air that 

 has been heated by compression, the tendency to expand is 

 decreased, and therefore the high pressure cylinder can do 

 more effective work. The mechanical inlet and out valves- 

 are of the Corliss pattern. 



The Ingersoll-Sergeant is a straight line single air cylinder 

 compressor. It does not take up much space, every part of the 

 machine is very accessible, and the piston can be removed from 

 either cylinder in a short time. The air cylinder is completely 

 jacketed, including both heads, near where the air is in great- 

 est compression, and consequently is hottest. The free air enter* 

 the cylinder through the piston. In Fig. 218, A is the circula- 

 ting water inlet ; B the circulating water outlet ; C the water- 

 jacketed drain pipe ; D the oil hole for the automatic oil cup ^ 

 E the air inlet, through piston inlet pipe ; E air discharge ; ti- 

 the pisoii inlet valve ; H discharge valves ; I water jacket. The 

 two inlet valves located in the piston, together with the tube, 

 are carried backwards and forwards with the piston. The large 

 ring air inlet valve admits a large area of opening with but 

 a small throw of valve, thus quickly opening a large supply 

 port. The movement of the valve is only about a quarter of 

 an inch. It is positive in its action. The valve on that face 

 of the piston which is towards the direction of movement is 

 closed, while the one on the other face is open. 



The haulage consists of two endless rope systems, one in 

 each tunnel. Each rope has a total length of from 3i to 4 

 miles, and has a loop branch. These ropes are driven by a pair 

 of R. and J. Morison and Bearby engines. Three skips are run 

 in a set, clipped to the rope with screw clips. Monkeys, which 

 are bars of wrought iron bent at right angle, and pivoted at 

 the bend, are arranged all the way down the incline on the up 

 track, so as to catch any skips that might break away. There 

 is also a main and tail rope system with two branches, worked 

 from the surface. Electric secondary haulage is being installed 

 for the branches. The axles of the skips are square where 

 they enter the hub of the wheels. They are fastened 011 by 

 driving in wooden wedges, and tightened by driving iron 

 wedges into the wood. 



Electric wire signals are used, and telephones are fitted 

 up throughout the colliery. 



A "belt driven Schiel fan, 12ft. Gin. in diameter, is used for 

 ventilating the colliery. A spare engine is provided, arranged 

 end on to the other. At the new air shaft, a Sirocco fan will 



