A dumb 4WD question

racerboy

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Pardon my ignorance, but when I was using my B2601 the other day to do some clearing for a lean-to attachment on my shed, I got hung up on a something (boulder or stump) in the mud. I was in 4WD, but only my left don’t and right rear tires were spinning as I tried to get free. Shouldn’t all 4 tires be trying to grab?
 

GreensvilleJay

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no... power goes to the wheel that has no traction on every vehicle with a normal differential. so only 2 wheels get power when in 4WD. that''s the nature of the beast.
Now IF the vehicle has a 'locking' or 'limited slip' diff, then BOTH wheels get power on that axle and if there's a limited slip or locker between front and rear axles, all 4 could get power.
 
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cthomas

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Nope, your tractor has an open diff. in the front and rear. The best you could do is to step on the diff. lock pedal(Tires NOT spinning) to get both rear tires and one front tire to spin. Do not use the diff. lock pedal unless it is needed. Again use the diff lock only when needed and tires not spinning. Don't feel bad as most 4WD tractors are like this. Back in the early 80's Audi had a diff. lock switch for only a few years(warranty claims kill it from people blowing the diff's up on dry pavement and going around a corner). The diff lock did come back, but a computer controlled it, therefore, kinda of idiot proof.
 
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The Evil Twin

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That's normal. For all intents and purposes, 2wd is really 1wd. 4wd is really 2wd. Very similar to a truck open differential. The one that slips gets the power. If you have a rear diff lock, then you het 3wd.
If all 4 wheels were locked together, turning would be a real problem. It would also tear up the surface you are driving on.
 
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The Evil Twin

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therefore, kinda of idiot proof.
Till they build a better idiot (like me). Lol! Ford did the same thing- no diff lock unless you are in 4wd, only below certain speeds, turns off after a predetermined time limit.... ugh. Took some time, but we finally got that fixed. Now if only I can get tow/ haul to stay on after turning the truck off....
 
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GrizBota

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Stand on the rear diff lock and both rear tires will have power. Might not even need 4WD. Your B2601 has both and they are independent of one another.
 
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Kubota Newbie

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Well, technically, there is "some" power still being applied to the the wheel that is not spinning although the amount is limited by the resistance to the spider gears in the differential proportional to the load effort (torque) required to rotate the wheel that is spinning. To equalize that load (on the rears at least) WITHOUT using the diff lock simply apply the brake lightly on the side of the tractor where the back wheel is spinning.
This has no real impact on the front drive since it has its own differential and no front brakes to manipulate the axle loading.
 
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Kubota Newbie

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Well, technically, there is "some" power still being applied to the the wheel that is not spinning although the amount is limited by the resistance to the spider gears in the differential proportional to the load effort (torque) required to rotate the wheel that is spinning. To equalize that load (on the rears at least) WITHOUT using the diff lock simply apply the brake lightly on the side of the tractor where the back wheel is spinning.
This has no real impact on the front drive since it has its own differential and no front brakes to manipulate the axle loading.
 

Motion

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As others have said do lock the diff if the tires are spinning, also go in a straight line, make no turns and when no longer needed, stop and ensure it disengages.
 

The Evil Twin

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Maybe there is hope for improving the front axle! Not available for our tiny tractors yet. Maybe one day!
 

NCL4701

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Well, technically, there is "some" power still being applied to the the wheel that is not spinning although the amount is limited by the resistance to the spider gears in the differential proportional to the load effort (torque) required to rotate the wheel that is spinning. To equalize that load (on the rears at least) WITHOUT using the diff lock simply apply the brake lightly on the side of the tractor where the back wheel is spinning.
This has no real impact on the front drive since it has its own differential and no front brakes to manipulate the axle loading.
That’s precisely how you “unstick” a stuck 2WD that doesn’t have a diff lock. Even, light pressure on the spinning wheel often works. Stabbing the brake on the spinning wheel similar to impact wrench mode works better. Not necessarily recommending the “stab the brake” method as I suspect that’s hard on the drivetrain but it does work better.
 

racerboy

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Thanks for all the feedback. I didn’t realize there was a diff lock on the tractor. My 2003 Tacoma has the same, and only for use in extreme circumstances.
 
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GrizBota

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Thanks for all the feedback. I didn’t realize there was a diff lock on the tractor. My 2003 Tacoma has the same, and only for use in extreme circumstances.
You are welcome. Based on your post, I sort of figured that was the case, which is why I mentioned it. That weird metal bar by you left ankle can be pretty helpful.
 

RBsingl

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And for any tractor that doesn't have a differential lock, LIGHT application of the rear brakes may get you through it by providing a little power transfer to both wheels.

Some of the modern pickups with open diffs now utilize this system via automatic application of one or more wheel brakes to the spinning wheel as needed. Applying brakes to both sides of the axle doesn't work nearly as well but sometimes it is just enough to get you going.

And as others noted, never engage the differential lock with the wheels actively spinning! Not following instructions is an excellent way to break something. Several years ago on YouTube, a proud poster wanted to share his knowledge of how using Chevrolet's launch control in a Corvette caused his differential to grenade.

The owners manual states, "with the vehicle in first gear and the clutch pedal depressed, slowly depress the throttle to full and keep it there. The ECM will limit the engine speed. Now keeping the throttle fully depressed, release the clutch and the ECM will manage engine power for optimal wheel slip on takeoff". What clueless owner did, and nicely showed video of his footwork, was to disengage clutch as he went to full throttle and then dumped the clutch not allowing launch control to go active first. So basically he did a full throttle clutch dump and the differential showed him what it thought of that behavior.

Rodger
 
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Soopitup

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no... power goes to the wheel that has no traction on every vehicle with a normal differential. so only 2 wheels get power when in 4WD. that''s the nature of the beast.
Now IF the vehicle has a 'locking' or 'limited slip' diff, then BOTH wheels get power on that axle and if there's a limited slip or locker between front and rear axles, all 4 could get power.
He does have a lock between front and rear, that's what makes it 4WD. But because front and rear are open he can still spin a wheel(s).
Generally speaking, 4WD has a locking center diff while AWD has a LSD center diff (or center diff effectively works as as LSD).

And if the limited slip is gear driven (helical/TORSEN) it will still act like an open diff if you lose enough traction on one wheel. EG one wheel in the air, or stomping on the accelerator on wet ice.
 

armylifer

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Maybe there is hope for improving the front axle! Not available for our tiny tractors yet. Maybe one day!
The product that he seems to be showing is very similar to a LockRite Locker that I have used in several of the rock climbing Jeep and Suzuki Samurai rigs that I have built over the years. The LockRite Locker has been a very durable and reliable differential locking system. It was extensively used by the off road driving community just because it was so useful and reliable in light off road vehicles.

This product may not be exactly the same as the LockRite Locker but the description of the product and the video seem to be similar. If I had a rig that needed the additional off road capability I would not hesitate to install such a product.
 
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The Evil Twin

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The product that he seems to be showing is very similar to a LockRite Locker that I have used in several of the rock climbing Jeep and Suzuki Samurai rigs that I have built over the years. The LockRite Locker has been a very durable and reliable differential locking system. It was extensively used by the off road driving community just because it was so useful and reliable in light off road vehicles.

This product may not be exactly the same as the LockRite Locker but the description of the product and the video seem to be similar. If I had a rig that needed the additional off road capability I would not hesitate to install such a product.
Or Aussie Locker. That is also similar. I've used those in lower power Jeeps with stock D30 axles. They were noisy compared to torque bias LSD (True Track) or Detroit, but very simple to install and reliable as all get out.
 

Flintknapper

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The product that he seems to be showing is very similar to a LockRite Locker that I have used in several of the rock climbing Jeep and Suzuki Samurai rigs that I have built over the years. The LockRite Locker has been a very durable and reliable differential locking system. It was extensively used by the off road driving community just because it was so useful and reliable in light off road vehicles.

This product may not be exactly the same as the LockRite Locker but the description of the product and the video seem to be similar. If I had a rig that needed the additional off road capability I would not hesitate to install such a product.
Correct. Appears to operate just like any of the 'Auto/Lunch Box' lockers that have been around in the aftermarket automotive industry for at least 35 yrs.