| Number of Part | Name of Part |
|---|---|
| 1 | Frame |
| 2 | Main-bearing cap |
| 3 | Main-bearing cap-bushing |
| 4 | Fly-wheel |
| 5 | Fly-wheel key |
| 6 | Fly-wheel key set-screw |
| 7 | Crank-shaft |
| 8 | Crank-disc |
| 9 | Crank-disc key |
| 10 | Crank-pin |
| 11 | Crank-pin cap |
| 12 | Crank-pin cap set-screw |
| 13 | Connecting-rod cap |
| 14 | Connecting-rod cap-bushing |
| 15 | Connecting-rod |
| 16 | Piston |
| 17 | Piston-pin |
| 18 | Piston-pin bushing |
| 19 | Piston-pin set-screw |
| 20 | Piston, inside ring |
| 21 | Piston, outside ring |
| 22 | Adjusting-bolt for piston-pin end of connecting-rod |
| 23 | Connecting-rod bolt |
| 24 | Guard-plate |
| 25 | Air-head |
| 26 | Air-head gasket |
| 27 | Air-head studs |
| 28 | Inlet valve and stem |
| 29 | Inlet valve-seat |
| 30 | Inlet valve-spring |
| 31 | Inlet valve-stem head |
| 32 | Inlet valve-stem cotter |
| 33 | Inlet valve-bonnet |
| 34 | Outlet valve |
| 35 | Outlet valve-spring |
| 36 | Outlet valve-bonnet |
| 37 | Water inlet pipe |
| 38 | Water outlet pipe |
| 39 | Air inlet pipe |
| 40 | Air outlet pipe |
| 41 | Unloader |
| 42 | Main-bearing grease-cup |
| 43 | Crank-pin grease-cup |
| 44 | Piston-pin grease-cup |
| 45 | Air-cylinder lubricator |
| 46 | Main-bearing studs |
| 47 | Main-bearing liners |
| 48 | Unloader regulating-cylinder |
The Norwalk standard compressor is shown in Figs. [361] and [362], the latter being a longitudinal section; Fig. [361] is a perspective view; the two compressors are driven by a single steam cylinder having an adjustable cut-off. The air valves are operated by a positive crank motion.
A view of a Pelton water wheel operating a compressor it shown in Fig. [363]. The cut represents a compound air compressor in which the valves are operated mechanically. The water which drives the wheel enters through the pipe and nozzle secured in the wheel pit, as represented.
Fig. [364] exhibits a belted duplex air compressor built by Allis-Chalmers & Co.
Fig. [365] shows a vertical duplex compressor driven by a belt.
Fig. 369.
All the latter, as may be seen by the engravings, have the positive valve motion operated by an eccentric. In selecting an air compressor the following points need consideration: 1, Number of cubic feet of free air required per minute; 2, Altitude, i.e., the number of feet above the sea level; 3, Steam pressure and air pressure.
The use of compressed air for operating mining pumps, while having advantages in some cases, is not to be recommended in all, particularly on account of the low efficiency of the plant as a whole. The loss due to leaks is serious, and the long line of piping with its numerous joints causes much trouble, delay and expense.