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ttiiggy
Premium
join:2001-03-27
Bozeman, MT

Does it matter which way an automotive rear end turns?

Does it matter which way an automotive rear end or transmission turns?

If you were to run one backwards, would it last 100k like it might if it were running forwards?
Would the gears or bearing wear out more running one way than another?

If a vehicle is rolling downhill it puts the wear on the other side of the gears. Are the gears designed to handle the wear on that side?


DarkLogix
Texan and Proud
Premium
join:2008-10-23
Baytown, TX
kudos:3
Well the pinion would be pulling the ring to it instead of pushing it.

so it might have some effect, or might not.


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to ttiiggy
Backwards transmission?!


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to ttiiggy
I can imagine cost cutting engineering would have weaker teeth on the side that isn't supposed to get stressed, or at least, a profile that isn't efficient.


mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3

3 recommendations

reply to ttiiggy
Yes, it would matter if done for an extended duration like you mentioned. For instance, a standard hypoid-gearset rear axle has a pinion gear that drives a ring gear against teeth that have a convex shape on the "drive side" and a concave shape on the "coast side".

Those shapes and the way they mate are designed to yield a quiet interaction, and long life. If you reversed that, you would have a noisier result, and shorter life, for the same reason.

Also most rear drive axles have oiling passages that depend on the lubricant being "slung" off the top of the ring gear toward the front of the case over the pinion shaft providing lubrication to the shaft and bearings. You would in not too long of a time starve the pinion bearing of lubricant, which of course is a fatal event...

Transmissions would also have similar issues, as the planetary gearsets within them are also designed with helical-cut gears that have a desired "drive side" versus the other.


PeeWee
Premium
join:2001-10-21
Madera, CA
reply to ttiiggy
dupe


PeeWee
Premium
join:2001-10-21
Madera, CA
reply to ttiiggy
As was said;
Well the pinion would be pulling the ring to it instead of pushing it.

Designed that way for good reason, that is the stress point. decelerating is quite a less load and is non-comparitive.
So yes it matters, critically.
--
Those that charge less for their work understand what their work is worth!


ttiiggy
Premium
join:2001-03-27
Bozeman, MT
reply to ttiiggy
I was looking at a long steep road. Downhill grade for a couple of miles.
Thinking about what could be made for a load for resistance against gravity instead of wearing on the brakes of a vehicle or engine compression.

Wondered about having the driveshaft turn a BIG fan blade or something that would load the drive train to act as braking.


cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
said by ttiiggy:

Wondered about having the driveshaft turn a BIG fan blade or something that would load the drive train to act as braking.

You would never move enough air that method to provide any significant braking power, at least in a timely manner to be useful. Conceivable you could use that power to spin up a massive flywheel to store the energy until the fan's resistance provided enough braking over time. But that's not practical, not to mention what happens when you need to brake and the flywheel is already spinning at capacity.

If you don't want to use friction braking, and compression braking isn't desired, then resistance or regenerative braking could be a possibility. The latter is how hybrid cars work. Instead of braking using friction, power is transmitted back to the electrical motor turned into a generator. The wheels spin the generator, producing electricity to recharge batteries that can be used to power the vehicle when it needs to accelerate instead of consuming fuel. On a much larger scale, locomotives do the same thing but instead of recharging batteries, the electricity is used to power banks of resistive strips (think electric furnaces). The heat is then discharged out the top of the locomotive by large fans.


ttiiggy
Premium
join:2001-03-27
Bozeman, MT
said by cdru:

said by ttiiggy:

Wondered about having the driveshaft turn a BIG fan blade or something that would load the drive train to act as braking.

You would never move enough air that method to provide any significant braking power

I'm not thinking the AIR movement by itself would act as braking.
I don't really care if it is BLOWING any air.
Mostly, I just want the drag of turning the fan.
said by cdru:

flywheel is already spinning at capacity.

I don't think I want to mess with a flywheel with the extra weight and bearings and balance and vibrations.

said by cdru:

If you don't want to use friction braking, and compression braking isn't desired, then resistance or regenerative braking could be a possibility. The latter is how hybrid cars work. Instead of braking using friction, power is transmitted back to the electrical motor turned into a generator. The wheels spin the generator, producing electricity to recharge batteries that can be used to power the vehicle when it needs to accelerate instead of consuming fuel. On a much larger scale, locomotives do the same thing but instead of recharging batteries, the electricity is used to power banks of resistive strips (think electric furnaces). The heat is then discharged out the top of the locomotive by large fans.

I did think about turning a generator but didn't know what to do with the energy if batteries didn't need charged.
I'm not excited about generating extra heat with resistive strips.
That is where I thought turning the fan blades in the air might create drag to slow the vehicle.

Beezel

join:2008-12-15
Las Vegas, NV
reply to ttiiggy
Well if it were a diesel I would say exhaust brake or automatic transmission retarder. But I really never investigated if gas engines can benefit form a exhaust brake, since it forces more exhaust back pressure on the pistons and rods. Automatic transmission retarders are more for commercial medium to heavy duty application transmissions and are very expensive and complex.