New-York tribune., 1920-01-07
Making One
i Wrist Pin No
Slight Matter
II. Houpts Tells How Many
Tests Materials Must Pass
in Essex Factory To Be
Accepted

sThe wrist pin is one of the small,
.st details entering into the construc-
tion Of an automobile" says Harry S.
Houpt, Essex distributor. Hidden
from sight by the cylinder walls it
carries the power generated by the
expansion of the burning gas from the
niston itself to the connecting rod
rhich, in turn, moves the crankshaft.
s at is part never seen by the owner,
md vet it is as vital to the operation
of she car as is the rear axle. To the
Ave all wrist pins look more or less
alike. Apparently just hollow tubes of
polished steel, their performance is
taken for granted.
aAnd yet wrist pin may be turned
.up out of any bit of steel by any me-
chanic and hardened by blacksmith,
or it may be made of special steel
psssing through score of operations.
The difference becomes apparent only
through actual use.
aWhen a shop mechanic attempts to
, make wrist pin the metal used is any
bar stock that happens to be handy.
After being turned up in lathe it is
heated in bed of Goals. The pin is
allowed to remain in the fire until the
workman thinks it is finished. Then
It is hardened after q haphazard
method that permits of the widest va
ration in results.
L "With the Essex the care lavished
son these bits of metal is typical of
the quality of material and workman
ship throughout the whole car. Every
wrist pin goes through twenty-six op-
erations and is forced to undergo the
most rigid tests before it is accepted
for use.
aWhen the special steel is received
in long bars from the furnaces it is
piled in the storeroom until a chemi-
cal analysis is made Of every lot. This
test made from filings shows the exact
amount of phosphorus, manganese,
carbon, nickel and sulphur in the steel.
Having this test as to their quality the
bars are given an acid bath to deter
mine whether they contain any seams
or flaws.
"If the bars come up to the standard,
they are sent to the stock room, Where
the ends are painted different colors. &C.
cording to the results of the analysis.
Each color specifies a different heat
treatment, the difference being deter
mined largely by the amount of car
bon in the metal.
1.-THE bars then go to the machines,
where they are cut, drilled, tapered
and turned. Next, they are packed in
carbonizing compound and placed in
q furnace, the heat being exactly con-
trolled by electric promoters. Two
open heat treatments follow, after
which the pins are ground to final size.
"At every step inspectors check the
accuracy of the workmanship and quail
ty of the material Micrometer tests
are made to see that the dimensions
ere exact to the fraction of thou
sandth of an inch. Then comes
aell test. The sound of another piece
of metal striking against the pin re-
veals by the sound any cracks or i'm
perfections not visible to the eye.
"Then comes the final test for hard
ness. A little ball on a machine, called
scleroscope, is dropped on the pin.
The distance of the rebound accurate
ly determines the hardness of the sur
face Of the pin. If the pin passes all
these tests, it is ready to become part
of finished motor, where it is again
subjected to scores of tests as part of
the engine before it is delivered into
the hands of an owner"