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Hypoid vs. Non-Hypoid
Thanks this was very helpful
Appreciate your time in posting. Sophia On Tuesday, 9 January 1996 03:00:00 UTC-5, Andy Dingley wrote: > Mark > wrote: > > >Can someone explain the difference between Hypoid and Non-Hypoid > >oil? > > "Hypoid" is not really a question of oil, so much as a question of > gearcutting. Old (1920's) rear axles used straight bevel gears to form > the crownwheel and pinion. These had two disadvantage, the pinion > shaft meets the crownwheel on its central axis, and the straight cut > gears are noisy. By using a more complex "hypoid" gear tooth shape (if > you look at a pinion, the teeth appear twisted) these problems can be > addressed. The more gradual engagement of the teeth along their length > reduces noise. By careful design of the geometry the pinion can be > made to mesh _below_ the axis of the crownwheel. As the centre height > of the crownwheel is fixed by the wheel height, this allows the > propshaft to be lowered relative to the car body, giving a clearer > floorpan and lower centre of gravity for better cornering. Hypoid > bevels are now universal in this application. > > Because of the sliding contact that hypoid gears make, their > hydrodynamic contact pressure is higher. To be suitable for use with > hypoid gears, a lubricant must be capable of resisting high pressures. > > Oils with "EP" ratings (Extreme Pressure) such as EP90 are required. > Some brands describe themselves as "hypoid" instead, a term which is > synonymous with EP. GL-5 is a formal API standard for this type of oil > (comparable to MIL-L-2105B/C/D) > > > The book is telling me to use Non-Hypoid gear oil 80W or > >80W/90 on the manual transmission and GL-5 hypoid gear oil 90W on > >the rear axle. > > A manual transmission won't usually contain hypoid gears, so it > doesn't need an EP oil. Rare exceptions are those transaxles where the > crownwheel and gearbox share the same lubricant. Although an EP oil is > more complex to manufacture, it has no disadvantages when used in > instances where the EP attribute isn't strictly required. Manual > steering boxes and other slow-moving oil-containing components are > often filled with 90 weight oil. It's usual to buy EP90 because that's > what the axle requires, then use the same oil for all other > components. > > There's little practical difference between 80 & 90 weights. I fill > everything with EP80 and I've never had a problem. > > There's an increasing trend amongst manufacturers to reduce the number > of different lubricant types required. My own gearbox (5 speed Range > Rover) runs on ATF, but 20W/50 engine oil or EP90 axle oil are equally > permissible. > > -- > Andy Dingley > > The Internet has given us all mountains of information at our fingertips. > ...and all most people want to do is pick their noses with them. |
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