2 Wheel Drive

TheMurf

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Equipment
BX1880.with loader and 48 inch deck. 1990 Gravel 12G Riding tractor.
Jun 25, 2022
60
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Upstate New York
Question, On a new BX can you use 2 wheel posi drive when mowing?! Can I engage the two wheel posi and just mow ? O,r is it only for straight line situations when you need it ? Just wondering..
 

imnukensc

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BX2380
Sep 10, 2015
412
271
63
Midlands of SC
I don't know what "posi drive" is, but I think you're asking about the differential lock. It is only for straight line and only when you need it.
 
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TheMurf

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Equipment
BX1880.with loader and 48 inch deck. 1990 Gravel 12G Riding tractor.
Jun 25, 2022
60
25
18
63
Upstate New York
I don't know what "posi drive" is, but I think you're asking about the differential lock. It is only for straight line and only when you need i


Thank you,yes that is what I am referring to. Posi is both rear wheels are engaged, like a car.. That is what I thought..
 

BigG

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l2501, FEL, BB, Rotary cutter, rake,spreader, roller, etc. New Holland TL80 A
Sep 14, 2018
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The locking differential should only be engaged when the wheels are not spinning. once you are free you should take your heel off of the lever and let it disengage. The tractor will not turn as sharp and it will scarf up with your yard if you try to drive it all the time with the differential locked.

you can mow with the 4 x 4 engaged. But it will also limit your turning radius. So if you need it use it. Steep hills or soft ground you can use both the 4 x 4 and locking differential.

I would suggest you sit down and read your owner manual to get a better understanding of how to use your tractor and get the most out of it without any damage.
 
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RalphVa

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Jan 19, 2020
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Charlottesville
Always use 4wd. Otherwise, you have 2 wheel brakes, NOTHING on the front. Could go skidding downhill and go sideways and turn over.
 
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TheMurf

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BX1880.with loader and 48 inch deck. 1990 Gravel 12G Riding tractor.
Jun 25, 2022
60
25
18
63
Upstate New York
Thanks gus, I have read my manual cover to cover. I only cut in two wheel drive..I was.,just asking if you can engage both rear wheels and leave it.. I was wondering if it works like a posi traction rear end in a car or truck.. That's all.. Haven't used it at all.
 

Henro

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Equipment
B2910, BX2200, KX41-2V mini Ex.
May 24, 2019
4,016
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Only use 4WD when it is needed.
If you live on hills it is almost always needed for safety....

Flat or relatively flat areas, different story. Nothing flat where I live so I use 4WD all the time...and have for 20 years...no issues...not a cure all though. Did put my B2910 on its side once...about ten years ago.
 

TheMurf

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Equipment
BX1880.with loader and 48 inch deck. 1990 Gravel 12G Riding tractor.
Jun 25, 2022
60
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63
Upstate New York
If you live on hills it is almost always needed for safety....

Flat or relatively flat areas, different story. Nothing flat where I live so I use 4WD all the time...and have for 20 years...no issues...not a cure all though. Did put my B2910 on its side once...about ten years ago

Henro, Having a tractor go over is not as hard as people think. Grew up in farm county upstate N.Y. been operating tractors for a long time. A second of not paying attention is all it takes. I know 4 wheel drive is nice but it can give a false sense of security. I spun a 4 wheel drive truck in a 360 one morning on a bridge. Made a complete circle. A pucker moment for sure.
 

Vigo

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B6100, B8200
Jan 9, 2022
179
81
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San Antonio Texas
You can leave it in 4wd all the time IF you basically never cross pavement/concrete, and IF you don't make tight turns. For some people that really is 'all the time', but for everyone else you should be avoiding 4wd unless you actually need it, just to prevent putting wear and tear on the machine for no benefit.

A locking diff will make the tractor only want to straight. You can still turn, but by doing so you are 'dragging' one of the rear tires along at a different speed than it is spinning at, so you're burning gas and rubber for nothing. Generally you would only activate a locking diff for a short time to get unstuck, or perhaps to drag an implement through the ground in a straight line only.

As far as cars, most cars actually do not have a diff lock or even a limited slip and have 'open' differentials. You could say most cars are really 1wd when it comes down to it. Power DOES transmit through both drive wheels until one of them loses traction, at which point the majority of power goes to spinning that wheel, and very little goes to the wheel that actually has traction to do something with it. This only matters when spinning tires, so for most people.. not that often!

Limited slips and locking differentials do exist on cars but are becoming more and more rare, partially because all modern cars have the ability to do what a tractor can do, which is apply a brake only to the wheel that's spinning, while letting the other one continue to push. It's fully automated and we call it traction control. If done well it is 'as good' as a limited slip or locking diff, but on a car that applies hundreds of horsepower and has much higher wheel speeds than a tractor, it also puts a lot of heat into the brakes to use them for this. Again, most people won't activate that feature often enough to notice any brake wear/fade. Actual mechanical limited slips are expensive and in addition also reduce the 'authority' of the ABS/Stability Control system to make the two driven wheels turn at different speeds, which stability control does to help restore directional control when you are sliding.

It's only fairly recently that cars have starting doing 'steering brakes' both for directional control and traction control even though it has been done for 100+yrs on tractors. I think Ford brags the new Bronco can do a tighter turn off road by locking up the rear brake on one side. Ya don't say! If only we'd thought of that a century ago! Oh wait, we did.
 
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TheMurf

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BX1880.with loader and 48 inch deck. 1990 Gravel 12G Riding tractor.
Jun 25, 2022
60
25
18
63
Upstate New York
Great explanation Vigo.of how a transaxle works. Always wondered why tractors don't have limited slip differentials..
 

Vigo

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B6100, B8200
Jan 9, 2022
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San Antonio Texas
Most types of limited slips would not play nicely with steering brakes.

Really, the advantage of limited slips vs lockers is all tied up in high-speed, high traction pavement driving that tractors never do. They could be the best option in some cases for cars, but never, as far as i can tell, the best option for a tractor (vs a locking diff).
 

TheOldHokie

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L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
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Most types of limited slips would not play nicely with steering brakes.

Really, the advantage of limited slips vs lockers is all tied up in high-speed, high traction pavement driving that tractors never do. They could be the best option in some cases for cars, but never, as far as i can tell, the best option for a tractor (vs a locking diff).
Never is one of the most dangerous words in the english language and will bite you more often than not.

Take a look at big articulated machines with full time AWD. Seems to work really well for them.

Dan
 
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Vigo

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B6100, B8200
Jan 9, 2022
179
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Never is one of the most dangerous words in the english language and will bite you more often than not.

Take a look at big articulated machines with full time AWD. Seems to work really well for them.

Dan
True enough! And someone always calls me on it. 😅

I think the awd on articulated loaders is hydraulic awd, as in each wheel has a hydraulic motor, and the motors might be diagonally linked, and the two circuits go through a hydraulic synchronizing thingy (basically 2 motors on a common shaft, forces the flow rate of each side to be equal). I don't know much about it. But if you diagonally cross-link the wheels each circuit has one wheel on the inside (slower during turn) and one on the outside (faster during turn) and if you make those two circuits go through a synchronizing thing (forget the term) then the sum of wheel speeds on each circuit has to stay equal. So it's a hydraulically linked awd system with limited slip functionality where wheels can turn different speeds for turning but they can't 'spin' much when they lose traction.

Im pretty sure big loaders, at least modern ones, don't have wheels riding a common axle with a mechanical differential in the middle. I also kind of doubt they have steering brakes!

But i drove one for like 2 minutes when i was 14, and other than that im just using my general mechanical background knowledge to make educated guesses.. could be WAY off.
 
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xrocketengineer

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Lifetime Member

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BX1880, FEL, Grapple, 36 in. Forks, 48in. MMM, Quick Spade, Ripper
Nov 14, 2020
489
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Merritt Island, Florida
When using the differential lock, you have to be gentle, there are no clutches involved, only four pins engaging to lock. So, you have to be stopped, then press on the pedal (it might not go all the way) and apply a slight amount of wheel movement in order for the pins to fall in the holes and the the pedal to go all the way and hold the pedal down while you need the lock. Release the pedal while going in almost a straight line when not needing the differential lock any longer.
Otherwise, this can happen:
Differential lock failure

Differential lock apart
 

Vigo

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B6100, B8200
Jan 9, 2022
179
81
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San Antonio Texas
I've also found that the diff lock sometimes won't disengage unless i steer back and forth a little while rolling. You can hear/feel when it happens on mine. Probably due to a wear pattern on the parts causing something that should slide freely to hang up a little unless you unload that surface. It is just spring tension that disengages it.
 

TheOldHokie

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L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
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True enough! And someone always calls me on it. 😅

I think the awd on articulated loaders is hydraulic awd, as in each wheel has a hydraulic motor, and the motors might be diagonally linked, and the two circuits go through a hydraulic synchronizing thingy (basically 2 motors on a common shaft, forces the flow rate of each side to be equal). I don't know much about it. But if you diagonally cross-link the wheels each circuit has one wheel on the inside (slower during turn) and one on the outside (faster during turn) and if you make those two circuits go through a synchronizing thing (forget the term) then the sum of wheel speeds on each side has to stay equal. So it's a hydraulically linked awd system with limited slip functionality where wheels can turn different speeds for turning but they can't 'spin' much when they lose traction.

Im pretty sure big loaders, at least modern ones, don't have wheels riding a common axle with a mechanical differential in the middle. I also kind of doubt they have steering brakes!

But i drove one for like 2 minutes when i was 14, and other than that im just using my general mechanical background knowledge to make educated guesses.. could be WAY off.
Yes, they are typically (cautious weasel word) hydraulic all wheel drive. Ever try to use the steering brakes on a standard L with HST o_O :D
When using the differential lock, you have to be gentle, there are no clutches involved, only four pins engaging to lock. So, you have to be stopped, then press on the pedal (it might not go all the way) and apply a slight amount of wheel movement in order for the pins to fall in the holes and the the pedal to go all the way and hold the pedal down while you need the lock. Release the pedal while going in almost a straight line when not needing the differential lock any longer.
Otherwise, this can happen:
Differential lock failure

Differential lock apart
No pins on the B7100. It uses two very stout rectangular dogs. Hard to shear but susceptible to wear at the corners of the dogs.

Dan
 
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ruger1980

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L4310 w/La682, L225
Oct 25, 2020
257
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CNY
Yes, they are typically (cautious weasel word) hydraulic all wheel drive. Ever try to use the steering brakes on a standard L with HST o_O :D

No pins on the B7100. It uses two very stout rectangular dogs. Hard to shear but susceptible to wear at the corners of the dogs.

Dan
Actually the vast majority of wheel loaders are transmission drive to axles with differentials. There are a number in the compact market that are hydrostatic as well as a few in the medium to large market. But usually still a hydraulic motor driving a transmission and axles. Once you get to the mining sector you can find electric wheel drive units.
I am sure there are some out there that do have hydraulic wheel motors but they are limited in numbers.

From my experience I have seen axles with open, torque proportioning. limited slip and locking differentials. Most are open and locking being actuated by generally hyd. oil and sometimes air.
 
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TheOldHokie

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Actually the vast majority of wheel loaders are transmission drive to axles with differentials. There are a number in the compact market that are hydrostatic as well as a few in the medium to large market. But usually still a hydraulic motor driving a transmission and axles. Once you get to the mining sector you can find electric wheel drive units.
I am sure there are some out there that do have hydraulic wheel motors but they are limited in numbers.

From my experience I have seen axles with open, torque proportioning. limited slip and locking differentials. Most are open and locking being actuated by generally hyd. oil and sometimes air.
:D

Dan
 
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Vigo

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B6100, B8200
Jan 9, 2022
179
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San Antonio Texas
Thanks for the info! I'd love to have more exposure to that type of equipment just for curiosity's sake.. but not sure i want to get roped into working on any..😅

And yeah my b8200 has the steering brakes and hydro pedal on the same side.. ive never even touched them!