How a differential works - Page 2 - JeepForum.com

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post #16 of 23 Old 01-27-2011, 03:11 PM
MO2500
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I know you have the answers to these questions but I'll try and play a long and will most likely learn something I did not know

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Originally Posted by mrblaine View Post
I have a question. Can you mesh a pinion gear into a reverse cut ring gear without reversing the rotational direction the gear teeth spiral around the pinion gear head?
I'm struggling to picture the gears meshing without having a ring and pinion in front of me. However, I believe (and I know I could very well be wrong) that you may be able to mesh a standard cut pinion gear into a reverse cut ring gear if you flip the ring gear over to the other side of the pinion. This would however, change the direction that the ring gear rotates.

Thinking about it more this might make the coast side of the pinion mesh with the drive side of the ring gear so I guess they really wouldn't mesh correctly.

Please, enlighten me if you could. I'm curious now

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Can you think of a way to run a low pinion gear set in a high pinion application and still run hypoid gears?
Possibly a flipped low pinion axle running portals that reverse the rotation of the hub. Modifications to the oiling passages and such to keep the pinion bearings alive.

That or run flipped axles with a drivetrain setup that reverses the direction the driveshafts are rotating. Like rear engine buggies and using FWD engines that spin the opposite direction. This I know little about.

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What distinguishes the drive from the coast side on a ring gear?

The drive side of a tooth on the ring gear is more vertical and therefor more efficient at transferring the forces as the teeth of the pinion and ring gear mesh. Greater percentage of the force applied goes into rotating the ring gear.
The coast side of the tooth is more angled and therefor there is a significant force vector perpendicular to the direction of rotation that makes the ring and pinion want to push away from each other (ofcoarse, using the example of a low pinion D30 in front application while driving forward). With enough force, the housing will deflect, the teeth on the pinion gear will ride up to the thinner potion at the top of the ring gear tooth and the tooth will fail.




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post #17 of 23 Old 01-27-2011, 10:02 PM
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Quote:
Originally Posted by MO2500 View Post
I know you have the answers to these questions but I'll try and play a long and will most likely learn something I did not know



I'm struggling to picture the gears meshing without having a ring and pinion in front of me. However, I believe (and I know I could very well be wrong) that you may be able to mesh a standard cut pinion gear into a reverse cut ring gear if you flip the ring gear over to the other side of the pinion. This would however, change the direction that the ring gear rotates.

Thinking about it more this might make the coast side of the pinion mesh with the drive side of the ring gear so I guess they really wouldn't mesh correctly.

Please, enlighten me if you could. I'm curious now
You missed the key part which was the reason they are called reverse rotation is the rotation of the direction the teeth spiral around the pinion is reversed from a standard gear set. No, the teeth do not mesh between the two.



Quote:
Possibly a flipped low pinion axle running portals that reverse the rotation of the hub. Modifications to the oiling passages and such to keep the pinion bearings alive.

That or run flipped axles with a drivetrain setup that reverses the direction the driveshafts are rotating. Like rear engine buggies and using FWD engines that spin the opposite direction. This I know little about.
What if you extended the pinion to the back of the ring and pinion and turned it from there?




Quote:
The drive side of a tooth on the ring gear is more vertical and therefor more efficient at transferring the forces as the teeth of the pinion and ring gear mesh. Greater percentage of the force applied goes into rotating the ring gear.
The coast side of the tooth is more angled and therefor there is a significant force vector perpendicular to the direction of rotation that makes the ring and pinion want to push away from each other (ofcoarse, using the example of a low pinion D30 in front application while driving forward). With enough force, the housing will deflect, the teeth on the pinion gear will ride up to the thinner potion at the top of the ring gear tooth and the tooth will fail.

Yep, the coast side is ramped and tries to push the pinion away from the ring gear under load. When the pinion tooth walks out high enough to push on the thinner top edge, you break teeth off or crack them at the root of the tooth.

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post #18 of 23 Old 01-28-2011, 06:06 AM
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Perhaps this is sticky worthy
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post #19 of 23 Old 01-28-2011, 08:20 AM
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Originally Posted by mrblaine View Post
You missed the key part which was the reason they are called reverse rotation is the rotation of the direction the teeth spiral around the pinion is reversed from a standard gear set. No, the teeth do not mesh between the two.
Ahh, I see. So "reverse rotation" is a correct term for the gear set. I feel that it is easier to call them "reverse cut" for the simple reason of not confusing people. "reverse rotation" makes some believe that they in some way changes the direction of rotation of the ring and pinion gear which is not correct. It only changes the direction the teeth are cut around the pinion and ring gear


Quote:
What if you extended the pinion to the back of the ring and pinion and turned it from there?
I suppose that would have the same reversing effect. Do you have an example of an axle like this or is this just an idea that would, in theory, work?

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post #20 of 23 Old 01-28-2011, 08:29 AM
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Originally Posted by MO2500 View Post
Ahh, I see. So "reverse rotation" is a correct term for the gear set. I feel that it is easier to call them "reverse cut" for the simple reason of not confusing people. "reverse rotation" makes some believe that they in some way changes the direction of rotation of the ring and pinion gear which is not correct. It only changes the direction the teeth are cut around the pinion and ring gear
Reverse cut and reverse rotation are both correct and like you, I've chastised many a folk over what I thought was a misnomer until I had someone who owns a large axle company hand my butt back to me.



Quote:
I suppose that would have the same reversing effect. Do you have an example of an axle like this or is this just an idea that would, in theory, work?
I think there is a Corvette axle like that, but I've never looked it up.

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post #21 of 23 Old 01-28-2011, 01:03 PM
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This is very worthy of Sticky classification. Would be nice if there were a bit of info to include after the video regarding how lockers tie this together (automatic and manual).
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post #22 of 23 Old 02-07-2011, 01:17 AM
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I would like to know how this scenario would work:

You take a LP front diff, but instead of having forward torque applied to the coast side (angled side) of the gearset teeth, you flip flop the gear pitch angles on the ring and pinion so that the gears would mesh on the "drive" side whilst torquing forward? That way you could have a LP front but without the R and P pushing eachother apart whilst driving forward.

Another idea is to have symmetrical pitch angles on both sides of the gear teeth so that they would be just as strong in forward or reverse directions?

I am sure there is some reason why this wouldn't work, but I don't have any hands-on experience.
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post #23 of 23 Old 02-07-2011, 07:38 AM
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Quote:
Originally Posted by btn View Post
I would like to know how this scenario would work:

You take a LP front diff, but instead of having forward torque applied to the coast side (angled side) of the gearset teeth, you flip flop the gear pitch angles on the ring and pinion so that the gears would mesh on the "drive" side whilst torquing forward? That way you could have a LP front but without the R and P pushing eachother apart whilst driving forward.
Not sure why you think you want a low pinion front, but you can do it the way you describe. It's done the other way all the time with low pinion axles to make them hi pinion. They simply flip them upside down and then run the motor the other way. As in the engine points backwards.



Quote:
Another idea is to have symmetrical pitch angles on both sides of the gear teeth so that they would be just as strong in forward or reverse directions?

I am sure there is some reason why this wouldn't work, but I don't have any hands-on experience.
It wouldn't be a hypoid gear then, it would be more like a spur and pinion gear and would make a lot of noise.

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