Determining bevel gear clearance

[woodman55]

One big problem I see with it being held in place with grease, is it being pushed out of position when the tooth sweeps into the valley between the teeth. To make this work I would almost think you would need to assemble it without turning anything. Then take it back apart, and measure the crush.

Yes I know I am kind of arguing against my idea, but that does not really matter. Finding a workable solution is the important thing.

 

[TheOldHokie]

One big problem I see with it being held in place with grease, is it being pushed out of position when the tooth sweeps into the valley between the teeth. To make this work I would almost think you would need to assemble it without turning anything. Then take it back apart, and measure the crush.

Yes I know I am kind of arguing against my idea, but that does not really matter. Finding a workable solution is the important thing.

A dial indicator is a workable and accurate solution. They are not expensive.

1 In. Travel Machinists Dial Indicator

Amazing deals on this 1In Travel Machinists Dial Indicator at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Dan

 

[woodman55]

If you put plastigage on the drive side of a tooth and turn the gears the teeth will close up against one another, lash is going to go to zero, and the plastigage is going to be shredded. No???

Dan

I know what you mean, normally you don't move anything when you use plasigage, but I am thinking without any real resistance, like a wheel being driven by a diesel engine it might stand up. ??? If you put it on the coast side I think it would just get pushed out of place, so the drive side is the only side it would work on. I can't seem to be able to copy and paste that section in my manual, but Kubota uses that procedure to check the lash between the drive axle bevel gear and the upper vertical bevel gear, and then between the bull gear and the lower vertical bevel gear. The procedure states to turn the axle, so Kubota must (hopefully) know what they are doing.

 

[Henro]

If you put plastigage on the drive side of a tooth and turn the gears the teeth will close up against one another, lash is going to go to zero, and the plastigage is going to be shredded. No???

Dan

Why would that happen? Gear lash is basically slop in the system, right? Something between the gear faces on either side would behave the same, wouldn’t it?

Just thinking analytically, not claiming to know anything. Just wanting to understand things.

 

[TheOldHokie]

I know what you mean, normally you don't move anything when you use plasigage, but I am thinking without any real resistance, like a wheel being driven by a diesel engine it might stand up. ??? If you put it on the coast side I think it would just get pushed out of place, so the drive side is the only side it would work on. I can't seem to be able to copy and paste that section in my manual, but Kubota uses that procedure to check the lash between the drive axle bevel gear and the upper vertical bevel gear, and then between the bull gear and the lower vertical bevel gear. The procedure states to turn the axle, so Kubota must (hopefully) know what they are doing.

You can't even let the weight of a crankshaft rest on plastigage without distorting it. Thats why it must be placed on top of the journal. I would like to see the Kubota description. Frankly I dont see how plastigage measures lash on either side. You could do better with a feeler gauge.

Dan

 

[Henro]

If you put plastigage on the drive side of a tooth and turn the gears the teeth will close up against one another, lash is going to go to zero, and the plastigage is going to be shredded. No???

Dan

But there is no drive side in a system that is designed to work in both directions…

And my understanding is gears are designed so there is no sliding between surfaces. I forget what this is called, but the result is the gear surfaces move in relationship to one another in a way similar to how a car tire turns against the road. We get lots of life out of tires when they are rotating, when braking or acceleration is not taking place.

Properly designed gears do not slide against one another. They just push the opposite tooth. Granted there may be a little slippage, but not much. It might even go completely away with use for all I know.

The plastigage should only be compressed. It should only feel compressive force, and not any sideways force.

My take on it anyway. No disputing a dual indicator is a good tool.

A second guess would be that the dial indicator would read the same regardless of where the gears were positioned. Because if the gears conform to each other, the distance between them should be the same over their range of interaction.

 

[TheOldHokie]

But there is no drive side in a system that is designed to work in both directions…

And my understanding is gears are designed so there is no sliding between surfaces. I forget what this is called, but the result is the gear surfaces move in relationship to one another in a way similar to how a car tire turns against the road. We get lots of life out of tires when they are rotating, when braking or acceleration is not taking place.

Properly designed gears do not slide against one another. They just push the opposite tooth. Granted there may be a little slippage, but not much. It might even go completely away with use for all I know.

The plastigage should only be compressed. It should only feel compressive force, and not any sideways force.

My take on it anyway. No disputing a dual indicator is a good tool.

A second guess would be that the dial indicator would read the same regardless of where the gears were positioned. Because if the gears conform to each other, the distance between them should be the same over their range of interaction.

Spur gear teeth mainly roll against each other. Spiral bevel gears slide across each other. That is why differential lubricants contain elevated levels of EP additives.

Every gear set has a drive and coast side which is defined relative to the direction of rotation. When you reverse the rotation drive and coast are swapped.

A dial indicator will tell you the exact (almost) distance the gears move at the pitch circle. That is the definition of gear lash and it may vary slightly around a gear due to gear cutting error as the gear is formed.

Machinery's Handbook contains a wealth of information on the topic.

Dan

 

[ejb11235]

Do we even know that the Kubota manual is directing the use of plastiguage? If I recall, OP said that the manual used the term "fuse" and wondered if that was plastiguage, and we're off to the races. Or has this simply become a thought problem?

Not ever having even opened up a differential before, it seems to me that you set the ring and pinion gears using the gear marking compound, and the lash is whatever it ends up being. Put another way, if you set up the ring and pinions so that the gear mating surface is in the correct position, what else are you going to do if the lash isn't correct? Obviously you have some latitude in adjusting the gear mating surface location (see the photo I originally posted) ... I don't know though if moving the mating position towards the inner area of the ring gear, or away from it, affects the lash. I'm thinking it doesn't.

 

[TheOldHokie]

Do we even know that the Kubota manual is directing the use of plastiguage? If I recall, OP said that the manual used the term "fuse" and wondered if that was plastiguage, and we're off to the races.

We do not. But the topic of proper measurement technique is still germane.

If you are going to setup a differential spend $40-$50 on the proper tools. Mistakes get costly.

Dan

 

[ejb11235]

We do not. But the topic of proper measurement technique is still germane.

Dan

I agree. Ok so would it be correct so say that the question at hand is "how do you measure lash when you can't use a dial guage?"

 

[TheOldHokie]

I agree. Ok so would it be correct so say that the question at hand is "how do you measure lash when you can't use a dial guage?"

If thats the question my answer would be "inaccurately".

Dan

 

[ejb11235]

If thats the question my answer would be "inaccurately".

Dan

You mean turning the driveshaft by hand back and forth doesn't give an accurate measurement?

 

[TheOldHokie]

You mean turning the driveshaft by hand back and forth doesn't give an accurate measurement?

Dunno but it might be

This is a relatively low speed/load gear set and probably not very sensitive to mildly excessive lash. As long as there is some and tooth contact is centered it is probably good to go. A highway vehicle is certainly going to be more demanding.

Dan

 

[Fordtech86]

You mean turning the driveshaft by hand back and forth doesn't give an accurate measurement?

If you do it enough it can be

 

[NorthwoodsLife]

Respectfully, we're kinda beating this up.
Having done a few gear changes in diffs over the years. I own and use the tools. I'm no professional diff guy, but I have a little experience.
The OP's original question with the manual's "fuse" or whatever the terminology may be, can be measured simply with Gear Compound. I've always used the yellow/green type with good results. The Permatex Blue may be good to go. IDK, never used it.

Backlash is measured with a caliper type tool that is dialed onto the Ring gear. While moved each direction it reads lash.

One shims or crush sleeves or otherwise, the X and Y axis btwn the axle linear and the pinion linear. Then backlash is checked and adjusted if needed. By adjusting the same shims etc. Or in some cases the carrier bearings and races, or whole axle housing must be replaced.

But... Nowhere in the OP's repair has lash come into play. Unless I'm seeing this all wrong, Kubota's manual description is concerning depth of gear mesh (or load bearing) surface. Especially, if it's too deep, it'll eat the gears and or bearings. Too loose would probably cause the same but in a longer timeline.

 

[TheOldHokie]

Respectfully, we're kinda beating this up.
Having done a few gear changes in diffs over the years. I own and use the tools. I'm no professional diff guy, but I have a little experience.
The OP's original question with the manual's "fuse" or whatever the terminology may be, can be measured simply with Gear Compound. I've always used the yellow/green type with good results. The Permatex Blue may be good to go. IDK, never used it.

Backlash is measured with a caliper type tool that is dialed onto the Ring gear. While moved each direction it reads lash.

One shims or crush sleeves or otherwise, the X and Y axis btwn the axle linear and the pinion linear. Then backlash is checked and adjusted if needed. By adjusting the same shims etc. Or in some cases the carrier bearings and races, or whole axle housing must be replaced.

But... Nowhere in the OP's repair has lash come into play. Unless I'm seeing this all wrong, Kubota's manual description is concerning depth of gear mesh (or load bearing) surface. Especially, if it's too deep, it'll eat the gears and or bearings. Too loose would probably cause the same but in a longer timeline.

Perhaps you could share that manual description so we can all better understand the OPs question.

Dan

 

[ejb11235]

Respectfully, we're kinda beating this up.
Having done a few gear changes in diffs over the years. I own and use the tools. I'm no professional diff guy, but I have a little experience.
The OP's original question with the manual's "fuse" or whatever the terminology may be, can be measured simply with Gear Compound. I've always used the yellow/green type with good results. The Permatex Blue may be good to go. IDK, never used it.

Backlash is measured with a caliper type tool that is dialed onto the Ring gear. While moved each direction it reads lash.

One shims or crush sleeves or otherwise, the X and Y axis btwn the axle linear and the pinion linear. Then backlash is checked and adjusted if needed. By adjusting the same shims etc. Or in some cases the carrier bearings and races, or whole axle housing must be replaced.

But... Nowhere in the OP's repair has lash come into play. Unless I'm seeing this all wrong, Kubota's manual description is concerning depth of gear mesh (or load bearing) surface. Especially, if it's too deep, it'll eat the gears and or bearings. Too loose would probably cause the same but in a longer timeline.

oh yeah, we're definitely well into "beating this up" territory. Yup, no doubt 'bout that.
@Fordtech86 it's about time you showed up

 

[NorthwoodsLife]

Perhaps you could share that manual description so we can all better understand the OPs question.

Dan

Dan:. I reread the original post. I stand corrected. The OP does mention lash. I don't have the manual. My mistake.

It's a tractor, not a racing car.

I'm not into online arguing. I was just trying to help out the OP.

My ego left many years ago. But sometimes all the banter draws me in. My apologies.

 

[TheOldHokie]

Dan:. I reread the original post. I stand corrected. The OP does mention lash. I don't have the manual. My mistake.

It's a tractor, not a racing car.

I'm not into online arguing. I was just trying to help out the OP.

My ego left many years ago. But sometimes all the banter draws me in. My apologies.

No need to apologize and I agree on the tractor not car assessment. I am sure thousands of tractor differentials have been successfully setup using nothing more than feel and some marking compound. Probably quite a few cars and trucks as well including a couple of mine. I stayed out until the topic of using plastigage to measure lash got going and then the thread went sideways. Not an uncommon occurence when I get involved

Dan

 

[woodman55]

I could not copy and paste so I took a couple of pictures. These are from my WSM for my L6060. They perform the same procedure for the lash between the bull gear and the lower bevel gear.

The only pressure on the plasigage will be the rotational force to turn the vertical shaft and the bull gear, which will be very little and the force it takes to force the tooth into the now narrower valley (due to the plastigage taking up some of the room).