Differential gear backlash adjustment Case 1494

[Henrik Jansson]

I am checking the backlash of the bevel ring gear, not because something was wrong, but because I was going to install new gaskets between gearbox housing and rear axle housing, and power take out housing.
And then everything is removed, I can see the differential, so I checked it out. The tractor has been used for almost 5000 hours.
I can see some small damages on the pinion gear, but not that much that I think it is a problem. There is no damages on the bevel gear.
But the backlash between bevel gear and pinion gears is up to 0,40 mm, and the manual says it should be between 0,18-0,23mm.
I guess this backlash increase over the time, so maybe this is normal after 5000 hours, but should I adjust this?
According to the manual it looks easy to adjust only this backlash, but, if I do that, do I have to adjust the pinion shaft protrusion first? In the manual they do so, but I guess they do so just because they renew the whole thing. But can I just adjust the backlash of the bevel gear?

 

[RGMartin]

I am of the mind set if they aren't broken, don't try to fix them. Gears wear into each other, if they have a normal wear pattern I would leave them alone.

 

[Bob]

I agree with RGM, at least up to a point.

Issue would be if the "load side" differential bearing is failing (or the rear pinion bearing, for that matter) and letting the gears move apart.

As you know, both the pinon bearings and the differential side bearings are "pre-loaded", get in there and pry things around a bit and see if any play has developed in the pinion or differential bearings.

Looseness there would be a BIGGER issue than a little gear wear.

 

[Henrik Jansson]

The differential bearing has a play of about 0,25mm.

 

[Bob]

Nearly nine thousandths of movement vs. "preload", must be some wear in the bearing(s) or it wasn't set up correctly?

Wonder what the preload is supposed to be, exactly, I have a manual at the shop, as I own a 1494, will try to remember to take a look.

<img src = "https://i167.photobucket.com/albums/u125/27Grainfield/CaseIH1494_zps401ecec4.jpg">

 

[Henrik Jansson]

I put some blue paint on. Then it looks like this.

 

[Henrik Jansson]

Do you mean nine thousands of 1 inch, or 0.009mm?
The manual says:
Put a 6 inch screwdriver in the differential cage, and turn the adjuster to the point there the weight of the screwdriver will just begin to move the ring gear down.

 

[rustred]

the thing is once the pattern is worn in and backlash has been set from factory or first time. you cannot change backlash, as this will change gear pattern and cause a howel. the fix is new gears. that blue paint can kinda see the pattern and it looks not bad. but there is special yellow gear marking paint. just paint the pinion teeth lightly then roll the pinion on the crown gear and you will see the pattern. you don't paint everything blue like that. I don't know he actual backlash spec on that but I would think it would be around .006 maybe up to .010 ? those metric numbers just don't seam right.

 

[Henrik Jansson]

Ok, thanks!
The backlash in inch should be 0,007-0,009 inch. That the same as 0,18-0,23mm.
1 inch = 25,4 mm.

 

[rustred]

ok that's easier to understand. means u have some gear and brg. wear.