Why use heavy oils in gearbox?

Ivan Vegvary · 2007-12-21T19:51:58+00:00

I am posting this so I can get educated. Just finished taking apart an automatic transaxle (1990 Nissan Maxima) for entertainment and "artsy" parts. From the bearings and races I see a welding positioner in my future!Anyway, the planetary gears are amazing as is the differential gear setup. All of this runs in a transmission fluid bath, which makes me wonder, why we use heavy gear oils for similar applications when not unitized with an automatic tranny? Granted this unit was not as heavy duty as would be required for a rear end of a truck, but, I am sure there are trucks with front wheel drive automatic transaxles. (Maybe not?).Educate me why heavy oils are used in gear boxes.Thanks,Ivan Vegvary

T

toolman946 18 years ago

Seasons Greetings to all from the frozen wasteland of the Canadian prairies!

I just want to say that I thoroughly enjoyed reading the opinions and comments posted on this thread.

How sad the current state of affairs around the planet that most web logs and forums seem to be an opportunity for dull minded and uneducated folks to crawl upon an anonymous soap box to spew venom and vitriol... kind of like an electronic version of the CB radio phenomenon of recent years past.

Thank you for restoring hope for our species.

l'll be visiting with you again soon.

Best wishes to all.

Michael

Vote

J

Jon Elson 18 years ago

That's the concept. The usual, hydraulic power steering system circulates fluid through a control valve that produces some restriction even when not turning, and it takes something like

1/2 - 1 Hp to drive the pump. The electrical power steering wastes far less power when not producing any steering effort, and as the motor usually moves pretty slowly, it is all current and very low voltage, so even when working the energy input is very low. When actually turning with hydraulic power steering, the energy waste is pretty large.

Yup, these mini-hybrid start/stop systems with the 42 V electrical system are going to be interesting. But, I'd like to see a REAL hybrid, with a tiny 12-Hp or so 2-cyl diesel and big batteries that could allow you to drive tens of miles at up to

30 MPH say, on electric alone.

Jon

Vote

J

Jon Elson 18 years ago

We used to have a Taurus that had variable-assist power steering. The power assist would fade out until it was totally manual at 45 MPH. The thing used to scare me because it required a LOT of steering effort to change lanes, etc. on the highway.

The control valve is mostly free-flow when not applying force to the wheel, but the pump still circulates the fluid through the whole circuit, and that burns some energy.

Too complicated. The new systems are totally electric, with a torque motor attached near the bottom of the steering column. No pumps, no hoses, no valves.

Jon

Vote

J

Jon Elson 18 years ago

What cars, or are these coming in the next couple years? I'd like to know more, I've been following stratified charge experimantal engines for decades, and always been mystified why they never went commercial.

Umm, maybe it was the gearing, but I had some friends that had RX-7s of various vintages, they all complained of rotten milage. (Well, my 86 MR2 also got poor milage, I know that was the insane performance gearing.)

Jon

Vote

R

RAMÂ³ 18 years ago

If it's a scam, it may well be more like the Tucker.

It'll be interesting to follow the "progress" of the Loremo...

Vote

A

ATP* 18 years ago

I hope it works, but at this point in my life, I need more than a 3D rendering to believe....It seems unlikely that they can achieve such an amazing increase over existing small, lightweight vehicles.

Vote

J

Jim Wilkins 18 years ago

Didn't you read my post? The Honda CVCC was a prechamber stratified charge engine.

=46rom the owner's manual of the 1980 Accord in my garage:

"The CVCC engine has two combustion chambers - the main chamber and the auxiliary chamber. The main chamber burns an extremely lean mixture which is ignited by the auxiliary. The auxiliary chamber burns a rich mixture which is ignited by the spark plug. Because the volume of the auxiliary chamber is smaller in comparison to the main chamber, the overall air/fuel mixture is very lean."

My roomier, heavier all-wheel-drive CR-V can achieve nearly the same MPG as the '80 and has twice the horsepower. CVCC Accords were relatively feeble.

Jim Wilkins

Vote

E

Ed Huntress 18 years ago

Didn't you read my post? The Honda CVCC was a prechamber stratified charge engine.

From the owner's manual of the 1980 Accord in my garage:

"The CVCC engine has two combustion chambers - the main chamber and the auxiliary chamber. The main chamber burns an extremely lean mixture which is ignited by the auxiliary. The auxiliary chamber burns a rich mixture which is ignited by the spark plug. Because the volume of the auxiliary chamber is smaller in comparison to the main chamber, the overall air/fuel mixture is very lean."

My roomier, heavier all-wheel-drive CR-V can achieve nearly the same MPG as the '80 and has twice the horsepower. CVCC Accords were relatively feeble.

Jim Wilkins

Yes, feeble is the word. IIRC, stratified charge (and other lean-burn technologies) took a dive when the NOx standards came in. They burn too hot, producing a lot of the stuff.

Does that ring a bell with anyone, or was it just hype to promote something newer?

-- Ed Huntress

Vote