first that the proper method would be a complete heat
treatment of the forging in the rough state, and machining the
rod after the heat treatment. After a number of trial lots, the
Signal Corps acceded to the request and production was immediately
increased and quality benefited by the change. This method was
later included in a revised specification issued to all producers.

The original system was one that required a great deal of labor
per unit output. The Lincoln organization developed a method of
handling connecting rods whereby five workmen accomplished the
same result that would have required about 30 or 32 by the original
method. Even after revising the specification so as to allow complete
heat treatments in the rough-forged state, the ordinary methods
employed in heat-treating would have required 12 to 15 men. With
the fixtures employed, five men could handle 1,300 connecting rods,
half of which are plain and half, forked, in a working period of
little over 7 hr.

[Illustration: Fig. 14.--Rack for holding rods.]

[Illustration: Fig. 15.--Sliding rods into tank.]

The increase in production was gained by devising fixtures which
enabled fewer men to handle a greater quantity of parts with less
effort and in less time.

In heat-treating the forgings were laid on a rack or loop _A_,
Fig. 14, made of 1-1/4-in. double extra-heavy pipe, bent up with
parallel sides about 9 in. apart, one end being bent straight across
and the other end being bent upward so as to afford an easy grasp
for the hook. Fifteen rods were laid on each loop, there being
four loops of rods charged into a furnace with a hearth area of 36
by 66 in. The rods were charged at a temperature of approximately
900 deg.F. They were heated for refining over a period of 3 hr. to
1,625 deg.F., soaked 15 min, at this degree of heat and quenched in
soluble quenching oil.

In pulling the heat to quench the rods, the furnace door was raised
and the operator pulls one of the loops _A_, Fig. 15 forward to
the shelf of the furnace, supporting the straight end of the loop
by means of the porter bar _B_. They swung the loop of rods around
from the furnace shelf and set the straight end of the loop on
the edge of the quenching tank, then raise the curved end _C_,
by means of their hook _D_ so that all the rods on the loop slide
into the oil bath.

Before the rods cooled entirely, the baskets in the quenching tank
were raised and the oil allowed to partly d