Differential Lock

[BotaLoda]

A few weeks ago my dif lock was not working, the pedal wouldn't go down. By habit I kept trying to use it and it did eventually lock. Then it stayed locked. I understand that you have to move a wheel a little for it to lock and sometimes do a zig zag or back up to unlock, but this was different.

Took it in for service and finally got a report on what went wrong. Now I forget the word he used, but said the things like dowels that go into the other part of the carrier to lock, well all of the pins were broke off!

No how in the heck can that happen? It's not like I put it in high gear with one wheel spinning at top speed then hit the lock pedal! (or anything remotely similar to that). The instruction manual is pretty vague it just says to lower the engine speed before engaging it? I would think that just going lighter on the go pedal would be the same? How do YOU engage the dif lock?

Thanks!

 

[SidecarFlip]

I have front than read lockers and when I engage them I'm at an idle in low gear. Sometimes disengagement can be tricky. I have to see saw the wheel back and forth to disengage. Rarely use them as they are for straight line operation only.

 

[SDT]

A few weeks ago my dif lock was not working, the pedal wouldn't go down. By habit I kept trying to use it and it did eventually lock. Then it stayed locked. I understand that you have to move a wheel a little for it to lock and sometimes do a zig zag or back up to unlock, but this was different.

Took it in for service and finally got a report on what went wrong. Now I forget the word he used, but said the things like dowels that go into the other part of the carrier to lock, well all of the pins were broke off!

No how in the heck can that happen? It's not like I put it in high gear with one wheel spinning at top speed then hit the lock pedal! (or anything remotely similar to that). The instruction manual is pretty vague it just says to lower the engine speed before engaging it? I would think that just going lighter on the go pedal would be the same? How do YOU engage the dif lock?

Thanks!

Ever go onto hard surfaces before the diff lock has disengaged?

SDT

 

[BotaLoda]

Ever go onto hard surfaces before the diff lock has disengaged?

SDT

No, not on purpose anyway. There are times I have them locked digging next to the driveway and then back out with my foot off the lock pedal, but you don't always know if it's unlocked. Even after the pedal pops up it would sometimes still be locked without me realizing it. Then yes it's turned on pavement while locked. If the pedal is stuck down, I go back and forth until it pops up.

 

[SidecarFlip]

No, not on purpose anyway. There are times I have them locked digging next to the driveway and then back out with my foot off the lock pedal, but you don't always know if it's unlocked. Even after the pedal pops up it would sometimes still be locked without me realizing it. Then yes it's turned on pavement while locked. If the pedal is stuck down, I go back and forth until it pops up.

That is where you broke the pins at. Turning with the lockers engaged put tremendous strain on the differential. The pins are the weakest point.

 

[BotaLoda]

That is where you broke the pins at. Turning with the lockers engaged put tremendous strain on the differential. The pins are the weakest point.

So if the dif lock pedal is popped up out of the lock position, how am I supposed to know if it's really unlocked or not? Turf up the grass I'm on trying to get only one wheel to spin?

 

[North Idaho Wolfman]

#1 Diff locks on these smaller models should never be engaged while spinning tires, no matter how slow. Stop spinning, step on pedal and move, you should also hear or feel when it unlocks, it's pretty distinct.
Yea, Never drive on asphalt when it's locked!

 

[BotaLoda]

#1 Diff locks on these smaller models should never be engaged while spinning tires, no matter how slow. Stop spinning, step on pedal and move, you should also hear or feel when it unlocks, it's pretty distinct.
Yea, Never drive on asphalt when it's locked!

If it doesn't go straight into lock, the rear wheels need to turn different speeds to get it to lock. No way around that. If the pins aren't lined up, one side or the other needs to turn.

So how about knowing when it's *really* unlocked?

 

[North Idaho Wolfman]

If it doesn't go straight into lock, the rear wheels need to turn different speeds to get it to lock. No way around that. If the pins aren't lined up, one side or the other needs to turn.

So how about knowing when it's *really* unlocked?

No they do not have to turn at different speeds to lock.

Read what I wrote, come to a stop, then step on pedal, then move, the lock will engage when you move.
Doing it while already spinning and you will break the pins again asureidly!

There is no magical formula to unlock, you will have to learn to hear or feel it.

 

[beex]

It’s rare that when you step down on the lock that the pins are aligned and it engages. The tires definitely have to move at different speeds to align and engage. The best way to do this is turn slightly while slowly moving with a light pressure on the lever. The lever will go down with light pressure when pins become aligned, then turn straight. Make certain the lever goes full down, for full engagement before doing your work. Don’t put heavy pressure on the lever it doesn’t do any good. To disengage, let up on lever move slowly turn slightly one way or other to relieve pressure on pins, lever will pop up. When lever is all the way up it’s disengaged, it cannot still be engaged with lever all the way up. Pins get broken when people put high differential torque on tires when partially engaged. Use only in low traction area. I use mine quit a bit. You get quit good at it after a while, I engage and disengage without thinking about it. It’s really helpful when on a slope and both high side tires spin. It’s a really tough mechanism in the differential, and can take a lot of differential torque when used properly, that’s what it’s for. If you broke one it’s operator error. I’ve been using diff locks on tractors for 45 years, never had a problem. Not trying to bragg here, just trying to encourage people to use it and not be afraid to use it, it’s really useful sometimes.

This is the second most misunderstood control on a tractor, the first is the 3pt speed control. The third is probably the mower height adjustment knob.


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[BotaLoda]

It’s rare that when you step down on the lock that the pins are aligned and it engages. The tires definitely have to move at different speeds to align and engage. The best way to do this is turn slightly while slowly moving with a light pressure on the lever. The lever will go down with light pressure when pins become aligned, then turn straight. Make certain the lever goes full down, for full engagement before doing your work. Don’t put heavy pressure on the lever it doesn’t do any good. To disengage, let up on lever move slowly turn slightly one way or other to relieve pressure on pins, lever will pop up. When lever is all the way up it’s disengaged, it cannot still be engaged with lever all the way up. Pins get broken when people put high differential torque on tires when partially engaged. Use only in low traction area. I use mine quit a bit. You get quit good at it after a while, I engage and disengage without thinking about it. It’s really helpful when on a slope and both high side tires spin. It’s a really tough mechanism in the differential, and can take a lot of differential torque when used properly, that’s what it’s for. If you broke one it’s operator error. I’ve been using diff locks on tractors for 45 years, never had a problem. Not trying to bragg here, just trying to encourage people to use it and not be afraid to use it, it’s really useful sometimes.

This is the second most misunderstood control on a tractor, the first is the 3pt speed control. The third is probably the mower height adjustment knob.


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That's the most accurate synopsis of the dif lock I've seen so far. Except I'd have to look at it internally to say if the pedal can come up with the diff still locked. I used mine a lot and wasn't scared of it, now I will be! I suppose if I'm trying to get the loader into some mulch and it spins, I'll try the lock in reverse where it has hardly any load on it. Yes engaging the lock all the way 1st try is going to happen maybe 1 out of 4 times, it's a hit and miss operation if the dowels are lined up. And yes if it doesn't lock first try, you need to let one wheel turn a little for the locking pins to line up. Or drive in circles until it lines up, which I could not do where I was at the time it acted up.

 

[SidecarFlip]

#1 Diff locks on these smaller models should never be engaged while spinning tires, no matter how slow. Stop spinning, step on pedal and move, you should also hear or feel when it unlocks, it's pretty distinct.
Yea, Never drive on asphalt when it's locked!

Lets expound on that a bit....



Pretty easy to tell if the diff lock is engaged on dry pavement by the tire scrub. All one has to to is look at the tires plus you can 'feel' it.

My M's have a different setup for the diff locks but the operation is the same. Rarely use them but I have and I use them carefully and never on dry pavement. Diff locks are tire eaters on pavement.

 

[troverman]

Lots of people of diff lock issues with the BX tractors. My guess is the mechanism is weaker than it should be. I don't really hear about broken diff locks on B Series, L Series, etc. Still, with a little caution, it should last forever.

A diff lock should be very strong and built to withstand some serious torque. Engaging under some wheel slip seems fine to me, as long as the wheel isn't spinning wildly fast. You pretty much need to have wheel speed differential to get the lock to engage anyway. You can feel when the diff locks right under your foot holding down the lever. When you see and hear the lever pop up, you are unlocked. I use mine frequently.

 

[BotaLoda]

Lets expound on that a bit....
Pretty easy to tell if the diff lock is engaged on dry pavement by the tire scrub. All one has to to is look at the tires plus you can 'feel' it.

My M's have a different setup for the diff locks but the operation is the same. Rarely use them but I have and I use them carefully and never on dry pavement. Diff locks are tire eaters on pavement.

I can feel the diff lock only when turning, I don't know how you could feel it when going straight, even on pavement? 4wd on pavement yes I've felt that!

Speaking of, do the front wheels actually travel faster than the rears in 4Wd? That's what the dealer told me, and he never said it's going to hurt anything except for the tires, not that I do it on purpose mind you, but I have forgotten until i feel it with the industrial bar tires.

 

[BotaLoda]

Lots of people of diff lock issues with the BX tractors. My guess is the mechanism is weaker than it should be. I don't really hear about broken diff locks on B Series, L Series, etc. Still, with a little caution, it should last forever.

A diff lock should be very strong and built to withstand some serious torque. Engaging under some wheel slip seems fine to me, as long as the wheel isn't spinning wildly fast. You pretty much need to have wheel speed differential to get the lock to engage anyway. You can feel when the diff locks right under your foot holding down the lever. When you see and hear the lever pop up, you are unlocked. I use mine frequently.

That's discouraging to hear. I may have been a little rough on the diff lock but not such that I ever thought I'd hurt it. Anyone ever seen em inside on a BX? Just how many pins are there? Seemed to me I'd often have to turn one tire pretty far till it engages.

Who knows, maybe it was a little off from new and now it will work better than ever? I can wish can't I?.

 

[SidecarFlip]

I can feel the diff lock only when turning, I don't know how you could feel it when going straight, even on pavement? 4wd on pavement yes I've felt that!

Speaking of, do the front wheels actually travel faster than the rears in 4Wd? That's what the dealer told me, and he never said it's going to hurt anything except for the tires, not that I do it on purpose mind you, but I have forgotten until i feel it with the industrial bar tires.

Called lead - Lag and is dependent on tire sizes. tires have to be matched to each other diameter wise.

I do a lot of roading with my tractors and they are always in 2wd.

 

[BotaLoda]

I sure am glad this was under warranty! I got to see the old parts (I should have taken pics). To lock the rear there are 4 pins about 5/16" thick and an inch or so long. These go (I think all the time?) through the diff carrier and when engaged go into the spider gear. I had pictured the pins at about 1/2" or so, these are NOT in my opinion up to the task and neither is the carrier they go through. The holes in the carrier were elongated to over twice the width of the pins, then there was some wear where the pins go into the spider gear but not much. Without seeing the new parts I can't be sure, but the elongated holes in the carrier may start out elongated and got worse? IDK, I'm going to jack up one wheel, hold it in lock and feel how much play the wheel has in locked mode.
Anyway the worst part besides the pins being too small is the fact that the spool or whatever you want to call it that the locking pins are mounted in never comes flat against the carrier and the spider gear. So it's not like it takes 100% shear strength, there is a gap that allows the pins to bend a little. I think if the pins were almost twice the thickness I'd be happy with the design, but not as is.

Let me tell you, as weak as those parts are, I will not treat the locking differential as a tractor feature, but instead like a very delicate afterthought in the design. Glad I wasn't paying the bill!

And as far as not using the diff lock on pavement, at times going down my steep driveway and using the brakes the one wheel will spin backwards and the other forward so it doesn't stop well that way. I don't know what would be harder on it, driving it down the hill there in 4WD, or with the rear locked? The drive does have some curves to it so it would be putting a strain on the diff lock. The different speeds of front and back in 4WD is also a strain on it.
See attached (warranty) bill.

 

[North Idaho Wolfman]

And as far as not using the diff lock on pavement, at times going down my steep driveway and using the brakes the one wheel will spin backwards and the other forward so it doesn't stop well that way. I don't know what would be harder on it, driving it down the hill there in 4WD, or with the rear locked? The drive does have some curves to it so it would be putting a strain on the diff lock. The different speeds of front and back in 4WD is also a strain on it.
See attached (warranty) bill.

If your having that issue you don't have enough rear ballast!

 

[SidecarFlip]

Think I'd get a bigger tractor.

 

[beex]

I don’t know, but 4 5/16” pins in shear mode are really strong, even with a gap.

But holy crap, spinning one wheel backwards going down the driveway on regular basis is an indication of something else going wrong, ballasts or something, which actually sounds dangerous to me. I would fix that problem some other way than 4wd or diff lock. No wonder why the diff lock broke, the 4wd will break too. Neither of those is the correct solution on the driveway. A bigger tractor will break too in that scenario. That’s not what I meant by “don’t be afraid to use it” when I said that above.

I can go downhill with a loaded bucket in low traction and not have that problem because I’m probably ballasted. I don’t do that regularly, I use the 4wd, but have forgotten to engage it sometimes.

BTW, loaded tires don’t really cut it with heavy weight in the bucket, not heavy enough and not as effective as weight 3’ behind the rear axle.

I’m guessing the higher breakage rate of diff lock on the bx is more due the bx having a higher occurrence of inexperienced operators than the hardware not strong enough.


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