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Sulphur is another impurity and high sulphur is even a greate...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Impact Tests
Impact tests are of considerable importance as an indication ...

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

The crankshaft was the most highly stressed part of the entir...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Critical Points
One of the most important means of investigating the properti...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

Application To The Automotive Industry


The information given on the various parts of the Liberty engine
applies with equal force to the corresponding parts in the construction
of an automobile, truck or tractor. We recommend as first choice for
carbon-steel screw-machine parts material produced by the basic
open hearth process and having the following chemical composition;
Carbon, 0.150 to 0.250 per cent; manganese, 0.500 to 0.800 per
cent; phosphorus, 0.045 maximum per cent; sulphur, 0.075 to 0.150
per cent.

This material is very uniform and is nearly as free cutting as
bessemer screw stock. It is sufficiently uniform to be used for
unimportant carburized parts, as well as for non-heat-treated
screw-machine parts. A number of the large automobile manufacturers
are now specifying this material in preference to the regular bessemer

As second choice for carbon-steel screw-machine parts we recommend
ordinary bessemer screw stock, purchased in accordance with S. A.
E. specification No. 1114. The advantage of using No. 1114 steel
lies in the fact that the majority of warehouses carry standard
sizes of this material in stock at all times. The disadvantage
of using this material is due to its lack of uniformity.

The important criterion for transmission gears is resistance to
wear. To secure proper resistance to wear a Brinell hardness of
from 512 to 560 must be obtained. The material selected to obtain
this hardness should be one which can be made most nearly uniform,
will undergo forging operations the easiest, will be the hardest
to overheat or burn, will machine best and will respond to a good
commercial range of heat treatment.

It is a well-known fact that the element chromium, when in the form
of chromium carbide in alloy steel, offers the greatest resistance to
wear of any combination yet developed. It is also a well-known fact that
the element nickel in steel gives excellent shock-resisting properties
as well as resistance to wear but not nearly as great a resistance
to wear as chromium. It has been standard practice for a number of
years for many manufacturers to use a high nickel-chromium steel
for transmission gears. A typical nickel-chromium gear specification
is as follows: Carbon, 0.470 to 0.520 per cent; manganese, 0.500
to 0.800 per cent; phosphorus, 0.040 maximum per cent; sulphur,
0.045 maximum per cent; chromium, 0.700 to 0.950 per cent.

There is no question but that a gear made from material of such an
analysis will give excellent service. However, it is possible to
obtain the same quality of service and at the same time appreciably
reduce the cost of the finished part. The gear steel specified is
of the air-hardening type. It is extremely sensitive to secondary
pipe, as well as seams, and is extremely difficult to forge and
very easy to overheat. The heat-treatment range is very wide, but
the danger from quenching cracks is very great. In regard to the
machineability, this material is the hardest to machine of any
alloy steel known.

Next: Composition Of Transmission-gear Steel

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