In 1926, the Packard Motor Car Company introduced the hypoid drive axle to the Motor City, and the rest of the industry wouldn’t catch up for another decade.

This fact is often misplaced due to the company’s sad decline in its final years, but in its heyday, Packard was known as an engineering company, famed in large part for its technical prowess. The Detroit automaker represented the cutting edge in engine development on land, sea, and air, and its engineering department was a hive of innovation. Because Packard produced only premium cars at premium prices, it could develop and market features that the other automakers, until they later achieved their vast economies of scale, couldn’t begin to consider. One example is Packard’s  advanced hypoid final drive, which the company introduced in August of 1926 on all its passenger cars across the line.

Before Packard, the standard of the industry was the spiral bevel gearset, as shown above. This ring-and-pinion configuration is relatively simple to produce, but it does have some drawbacks, including classic gear whine and limited tooth contact area. The centerline of the pinon (driving) gear is directly on the centerline of the ring (driven) gear.

In 1925, the Gleason Gear Works of Rochester, New York came up with a rather similar looking—but in fact very different—type of gearset it named hypoid. (The term is short for hypocycloidal curve, which is the actual shape of the gear teeth.) These teeth are longer and more fully engaged, so they can carry more torque. The gear centerlines do not intersect. Rather, the pinion is offset from the ring gear centerline a significant distance, called hypoid offset or hypoid distance. Hypoid is significantly quieter than spiral bevel, since the gear contact is a mixture of rolling and sliding. In that regard the hypoid gearset has been described as a sort of cross between a spiral bevel and a worm gear, and the greater pressure loading between the teeth required improved, high-pressure gear lubricants.

Packard quickly seized on the innovation and negotiated permission to produce the gearset from Gleason, which also sold to Packard the sophisticated machine tools required to manufacture the complex profiles. The new final drive (above) employed a hypoid offset of two inches and this interesting detail: an additional support bearing on the nose of the pinion gear, like the Ford 9-Inch of many years later. (Read about the Ford 9-Inch here.) The new drive was introduced in August of 1926 on Packard cars across the board: Fourth Series 426 and 433 six-cylinder cars and the Third Series 336 and 343 straight eights. (Third Series 336 Runabout below.) For the rest of the company’s history, Packard used hypoid gearsets exclusively.

The rest of the auto industry did eventually accept the hypoid gearset, but not for another decade. The other automakers did not choose hypoid for its greater strength and reliability, or for its quieter operation, but because the offset pinion permitted a lower driveshaft—and thus a lower passenger floor and a lower roofline, the hot styling trend of the time. Chrysler adopted hypoid in 1935, followed by Cadillac and Buick in 1937, while Ford stubbornly clung to its old spiral-bevel V8 driveline until 1949.