COAL - Clpdigital.org

32 THE COAL TRADE BULLETIN.
while motors of a special type weighing from 4 1 /.
to 6 tons, are used for gatnering, and are doing
very satisfactory work.
All the coal at Iselin is produced by Ingersoll-
Sergeant pick machines, and the compressed air
plant is of such an advanced and notable character
that it is worthy of detailed and extended notice.
It represents in all particulars the best features
of compressed air as applied to the production of
coal, and from an economic standpoint is probably
unsurpassed by any coal plant of any description
anywhere, and is the result of an experience by
this company extending over many years.
The two compressors which supply the power
for operating the coal cutting machinery were
built by the Ingersoll-Sergeant Drill Co. (Fig. 3.)
They are Corliss driven of the semi-tangye frame
type; have cross-compound steam and air cylinders
and are designed to operate non-condensing; each
has the following: High pressure steam cylinder,
23-inch diameter by 42-inch stroke; low pressure
steam cylinder, 38-inch diameter by 42-inch stroke;
low pressure air cylinder, 37-inch diameter by 42-
inch stroke: high pressure air cylinder, 23'/i-inch
diameter by 42-inch stroke; receiver intercooler,
54-inch diameter by 15 feet 6 inches high.
When operating at a speed of 75 revolutions per
minute, each compressor has a piston msplacement
of 3,790 cubic- feet per minute and is designed for
a final working air pressure of 90 to 100 pounds
per square inch. These compressors represent
the highest development of machinery of this class.
Fig. 4. Interior of Tipple at the Iselin Plant.
The steam valve gear is of the latest improveu
Corliss type, fitted with vacuum dashpots; the
valves slotted at one enu to receive the tee shall
heads of the valve stems, and are so constructed
that any valve can be taken out without disturbing
the valve stems or changing the adjustment of
the valve gear. The air cylinders are equipped
with the well known piston inlet valve. The
weight of each compressor is over li«,000 pounds.
The intercooler for eacn compressor is connected
between the high and low pressure air cylinders
and contains a nest of tinned brass tubes through
which water circulates, and each of tnese coolers
has ample cooling surface to reduce the air to
its initial temperature before entering the high
pressure air cylinder. In addition to this, each
intercooler has a receiver capacity to hold suffi­
cient volume of air to maintain a uniform intake
pressure for horse-power cylinder.
The mining machines are the very latest development
of the "puncher" and must not be confounded
with old and obsolete types wnich they
only resemble in outward appearance. The improvements
effected in pick machines during the
last decade have been so marked that their cutting
capacity has been almost doubled, while ease of
operation, simplicity of construction and absence
of repairs have created for them an unprecedented
market. The type used exclusively at this colliery
is the H-7 model of the "New Ingersoll"
puncher, which weighs 700 pounds and undercuts
5 feet. This was finally adopted after several
other types had been thoroughly tested.