Tim Radsick posts:
>I have a very basic question -- what does hypoid mean? Also, I have
>been told not to use gear oils with high sulfur as this will degrade
>the coatings on the tranny components. Is this an effect which
>usually takes place only at operating temps or did the 3 months of
>room temperature contact with Sta-Lube 90wt already do its damage?
>One
>last question, how do you know if a gear oil contains sulfur -- is
>this related to "hypoid"?
A hypoid is a mathematical curve - I don't have my math encyclopedia
with me right now, so I can't give a formula. Probably irrelevant
anyway. Older transmissions (like my Midget's) use straight-cut
gears - this means that the gear teeth, if you cut through them,
would have a rectangular cross-section. Hypoid gear teeth (surprise)
have a hypoidal cross-section. Straight-cut gears are noisier than
hypoid gears, and I think they wear out more rapidly. Hypoids mesh
more smoothly, but apparently the pressure at the points of contact
is greater; this means a special type of oil must be used. I have
always used standard SAE 80W-90 EP hypoid oil that you can get
anywhere. I don't know anything about the sulfur content.
Michael Flora
NASA - Marshall Space Flight Center
|