66
MESSRS. SCHNEIDER AND CO’S WORKS.
Hardening by immersion is effected in a wrought-iron
tank 5.500 metres (18 ft.) in diameter; and 7.300 metres
(24 ft.) deep ; this tank is filled, according to circumstances,
eithei- with oil or water. This plant is only now used for
hardening special pieces, as armour-plates are always
water-hardened by one or the other of the sprinkling
processes above described. When a niece has to be
which is lifted off by a travelling crâne when a plate is to
be put in or taken out. The other furnace is 6 metres
(19 ft. 8 in.) long, with three fires on each side. These
furnaces are used for heating large armour-plates préviens
to their being hardened, either by immersion or by sprink-
ling. Thin plates are heated vertically in a similar furnace,
and are hardened by immersion in a water tank placed in
Details of Cementing Furnace; Armour-Plate Department. (See page 62.)
hardened in water, a pump is used to empty the tank
and transfer the oil to another reservoir; this pump also
serves to agitate the oil or the water during the hardening
operation. The oil can be afterwards admitted to the tank
through a series of valves.
Two furnaces placed near the tank serve to heat large
armour-plates vertically. One is 10 metres (32 ft. 9 in.)
long; 3.500 metres (11 ft. 6 in.) high; and 1.500 metre
(4 ft. 11 in.) wide. The top is closed by a movable arch,
the same line as the furnace. This furnace can be opened
at one end, and the plate dipped rapidly, without having
lost any appréciable amount of heat. A fourth furnace,
with a revolving hearth, is used for heating gun parts,
such as hoops, trunnion rings, &c. Near this is a round
wrought-iron tank filled with water, in which the pieces
are dipped.
m. ft in.
Diameter of tank ... ... ... 2.450 8 0|
Depth ... ... ... ... 4.000 13