Hypoid gearsets exhibit quite a lot more sliding
contact where the gearteeth mesh than normal gears.
Hypoid is short for hyperboloid of revolution, the
geometric relationship that is used to derive the
geartooth design and profile. Compared to beveled spur
gears, the rotational axes of the two gears are offset
from one another. Compared to worm gears, the axis of
the pinion gear is also offset to one side of the ring
gear. The idea is to maintain the maximum amount of
tooth-tooth contact, with minimum clearance and
friction. This makes them strong, quiet, and
efficient.
The sliding at the line of contact creates very high
shearing forces on the lubricant. High enough that it
will break down the long molecule chains into smaller
lighter chunks of lower viscosity, and in some cases
with higher volatility.
Hypoid specified lubricants are formulated to resist
this shear breakdown.
Carter Shore
--- Dean Rayner <dean_rayner@mac.com> wrote:
>
> >> recommend using a non-hypoid oil(what does hypoid
> mean?)
>
>
> Hypoid gears are special bevel gears used in the
> differential of an automobile to connect the drive
> shaft to the rear axle.
> (from:Encyclopedia.com)
>
> Dean Rayner.
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