Differential Lock

troverman

Well-known member

Equipment
MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
1,184
263
83
NH
The standard B is a much more deluxe tractor than the standard L these days it seems. You get a nicer platform with a much smaller transmission tunnel hump, more leg room, and a rubber floor mat. You also get a little storage bin with a 12v outlet for charging. You get the electric over hydraulic PTO switch, and you get telescopic 3-point stabilizer arms. You also get a seat with armrests and a tilt steering wheel. The standard L gives you none of that. About the only advantage I see with the standard L from a 'features' standpoint is the fact that it has high and low beam headlights which are better than the B series lights...and possibly a larger toolbox.

The standard L is Kubota's best-selling tractor; it's size, weight, and power options make it an ideal choice for many so long as the price is good. By cutting off a lot of these little features, you can get an L for not much more than a B, and many people look at that as getting more tractor for your money.
 

Henro

Well-known member

Equipment
B2910, BX2200, KX41-2V mini Ex.
May 24, 2019
5,116
2,341
113
North of Pittsburgh PA
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.


Sent from my iPad using Tapatalk
OK, but the only time I want to use the differential lock is when I am stuck, so there is no tractor movement possible. But I suppose the tractor could “think” it was moving as one front and one rear tire spin. I have always engaged the differential lock with a rear tire turning slowly.

I suppose this is OK?
 

beex

Member
May 21, 2019
312
5
18
on my bx
Yes, it’s ok. And there’s really no other way to do it when your stuck. Turn slowly to get the pin alignment, make sure the lever is goes all the way down before trying to get unstuck. If you’re stuck with one rear not turning, you’re in a low traction situation, won’t hurt the diff lock, that’s what it’s for.


Sent from my iPad using Tapatalk
 

ya472

New member

Equipment
bx25
Aug 5, 2016
3
0
1
Qualicum
I don’t know, but 4 5/16” pins in shear mode are really strong, even with a gap.

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.

I put 1500 hours on BX25 when the diff-lock would not disengage, due to broken pins. I posted a series of YouTube videos (under ya472 ) showing the process to dismantle, inspect the damage and modify serious deficiencies. At 2540 hours, the pins broke again. THIS time(October/2020), I am taking the old undamaged carrier, other than the elongated holes, to a machine shop and have them install new LARGER pins in the collar and drill larger holes in the case and gear. I will be posting further video, but YES, sheer strength should not shear 4 - 5/16" pins, but FLEX and LEVERAGE does, because of the distance from the collar to the gear, including the 3/8" gap between the gear and housing. The soft metal of the carrier elongates because of the stress. BIGGER pins are necessary. Hopefully, larger holes in the gear won't weaken it.