Gears Without Chips

Gears, high-accuracy steel parts which must take heavy punishment, are traditionally made by cutting the shape from solid metal. It is slow, painstaking work. Last week Timken-Detroit Axle Co. an nounced they had found a new way to make gears.

Before the war, Timken-Detroit, the only U.S. company making high-traction gears for all-wheel-drive trucks, had three machines, each turning out twelve pinions an hour -- enough for one six-wheeler. As military trucking increased, Timken-Detroit engineers could foresee the bottle neck. They decided to try the impossible -- to forge gears to the unheard-of tolerance (for forging) of .001 in.

They had trouble. Under the necessary 3,000-ton impact, dies broke or spread, forgings cracked. If both the die and the forging stood up, they could expect to run off only about ten gears before the die was worn out. Then they thought of burying the die in solid steel so that it could not stretch, of doing the job in five successive squeezes instead of a single bump.

Last week Timken-Detroit was making 300 pinions an hour on one machine. The gear teeth need no machining, come out of the dies cleanly accurate. The forging process produces tougher gears, will save about a million pounds of steel.

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