APPENDIX II
317
These
engines were intended to hoist six loads, each weighing 1600 lbs., from
the 1000-foot level in 45 seconds, including filling, starting,
discharging, and stopping; but they do it in from 30 to 35 seconds.
All
the steam cylinders are fitted with the Corliss valve gear, having
vacuum dash-pots, the cut-ofF being effected by the same lever that
works the throttle valves.
Reversing
is effected by ordinary links worked by eccentrics fitted on the
tail-shafts ; the reversing engine being fitted with a floating lever
so that the motion of the piston coincides exactly with the motion of
the small hand lever.
The
two high pressure cylinders exhaust into the receiver, which is 5 ft.
diameter by 18 ft. long, fitted with sixty-eight 2-inch wrought-iron
tubes, through which live steam from the high-pressure jackets, but at
a reduced pressure, is constantly circulating. The object of this
receiver is to supply the low-pressure cylinders with a considerable
volume of dry steam to facilitate a quick starting away. An 8-inch
balanced throttle valve admits steam to the high-pressure cylinders,
and a similar valve, 12 inches in diameter, admits steam from the
reheater to the low-pressure cylinders.
Each
high-pressure cylinder is jacketed with live steam at full boiler
pressure, the water of condensation together with a certain amount of
steam passing through a Watts pressure regulator, which reduces the
pressure in the jackets of the reheater and low-pressure cylinders to
about 30 lbs. The final water of condensation is discharged
automatically by a displacement trap into the hot well.
Each
air pump of the ordinary marine type is worked off the cross-head. The
condenser, 6 ft. diameter by 16 ft. long, fitted with 125 wrought-iron
tubes 3^ in. outside diameter and 16 ft. long, is situated just outside
the winding-engine house. All the water pumped from the mine passes
through this condenser on its way to the floors.
A
circulating pump on the end of one of the tail-shafts supplies water
for jet injection whenever the mine pumps are not supplying sufficient
water to condense the steam.
L. I. SEYMOUR,
Mechanical Engineer for D. B. C. M. Ltd.
