Grand L Differential Lock Operation

[buck12]

I now have 35 hours on my 5460 Grand L and I have yet to master the differential lock operation. On my Mahindra 2615, I have owned for 12 years I push the the lock pedal while the tires are not moving. Once the tires start moving it takes a partial rotation and differential locks.

On the Kubota, if I push the pedal while the tires are not moving it stalls the tractor when I push the hydro pedal. If push the lock pedal while the tires are moving it is hit or miss if the lock engages. The manual is next to useless on this feature. What am I missing? Is there a problem with the tractor?

 

[Roadworthy]

You may have a tractor issue. I have the Kubota L2501. The differential lock on this tractor is controlled by a pedal operated by my left foot. It ALWAYS engage when depressed.

 

[5030]

First off, you need to be in LOW range. secondly, don't have the wheels spinning and engage the diff lock, you destroy it. Very expensive repair.

 

[PHILIP8N]

I wonder if the tractor stalls because you have taken weight off of the seat with all the pedal movement and the safety system is kicking in? The diff lock pedal has a strong spring, and takes a fair amount of force to keep it depressed. I changed my diff lock pedal spring out for one with less tension several years ago, works much better now. Philip.

 

[PHILIP8N]

Check out my post on page 2 and 3 of this thread. Philip. https://www.tractorbynet.com/forums/kubota-owning-operating/228484-5740-dif-lock-lever-2.html

 

[The Fred]

I wonder if the tractor stalls because you have taken weight off of the seat with all the pedal movement and the safety system is kicking in? The diff lock pedal has a strong spring, and takes a fair amount of force to keep it depressed. I changed my diff lock pedal spring out for one with less tension several years ago, works much better now. Philip.

:thumbsup: agreed mine is tricky also.

 

[jmc]

Check out my post on page 2 and 3 of this thread. Philip. https://www.tractorbynet.com/forums/kubota-owning-operating/228484-5740-dif-lock-lever-2.html

I had missed that modification. Well done, well documented.

 

[RjCorazza]

I think philip8n has it.
On my first tractor B8200 2wd, I actually wrenched my back bad using the diff lock. I heard muscles tearing!
Subsequent 4wd tractors have rarely required using the diff lock, or I would look into the mod.

 

[Gordon Gould]

I have a 2001 L3010 and have made extensive use of the diff-lock over the years working in the woods. I have never had any problems with it. The secret is to engage it before you need it. In other words with experience you can anticipate the trouble spots. Per the manual I always engage it when both rear tires are turning at the same rate and the tractor moving in a straight line. Never engage it when one tire is slipping or rotating faster than the other as in a curve. Push your heel on the pedal and you will feel it go into engagement. When you release the pedal if it doesn't pop out of engagement push on one then the other steering brake and it will pop out. Do not leave it engaged in a turn. No seat switch on this older model so spring tension is not a problem but the spring is fairly stiff to pull it out of engagement when the pedal is released.

gg

 

[buck12]

I wonder if the tractor stalls because you have taken weight off of the seat with all the pedal movement and the safety system is kicking in? The diff lock pedal has a strong spring, and takes a fair amount of force to keep it depressed. I changed my diff lock pedal spring out for one with less tension several years ago, works much better now. Philip.

That is something I will check this weekend. I honestly don’t know if this tractor has the seat switch. My Mahindra does not have a seat switch and with the cap on the Kubota I don’t think I have stood up while using the tractor.

 

[buck12]

I have a 2001 L3010 and have made extensive use of the diff-lock over the years working in the woods. I have never had any problems with it. The secret is to engage it before you need it. In other words with experience you can anticipate the trouble spots. Per the manual I always engage it when both rear tires are turning at the same rate and the tractor moving in a straight line. Never engage it when one tire is slipping or rotating faster than the other as in a curve. Push your heel on the pedal and you will feel it go into engagement. When you release the pedal if it doesn't pop out of engagement push on one then the other steering brake and it will pop out. Do not leave it engaged in a turn. No seat switch on this older model so spring tension is not a problem but the spring is fairly stiff to pull it out of engagement when the pedal is released.

gg

With my Mahindra I have used the differential lock for years and used it often. But I am obviously doing something wrong with the Kubota and the manual is of little help.

 

[Chewwy]

With my Mahindra I have used the differential lock for years and used it often. But I am obviously doing something wrong with the Kubota and the manual is of little help.

Sorry. Nothing too complicated about the NORMAL operation of the diff lock control. It appears something NOT normal about this situation. Lacking “miracle” answer here, should work with your local dealer to determine the solution.

 

[Fallon]

With any manual diff lock, you should be safe engaging it as long as the wheels are turning at the same speed. I generally try to engage mine while I'm moving before things get stuck. But engaging the different lock after you get stuck is fine as long as you stop moving the tires first.

You break things quickly if you engage the diff lock when the tires are spinning at different speeds.

You shouldn't notice any significant load or anything if you engage the diff lock on solid ground when going straight. If the engine is lugging or stalling when you engage the diff lock something is probably busted. Turning with the diff lock on will definitely cause the machine to buck a bit & load the engine a bit. But that shouldn't stall a HST machine at all in low, probably medium either even when turning unless something was busted or you had an external load of some sort.

 

[buck12]

I spent a little time on the tractor this weekend. Here is what I found. With the tractor completely stopped, if I depress the differential lock pedal with the throttle at operating speed when I depress the hydro pedal it stalls. If I stop the tractor and move the throttle lever down (slow down engine speed) then depress the differential lock pedal, then move throttle lever to normal operating speed, then press the hydro pedal everything functions normally.

Is this standard on a HST tractor? My standard practice for years on my gear drive tractor was to stop movement press differential lock pedal and then move. Throttle setting does not matter on the gear drive Mahindra.

 

[Fallon]

I spent a little time on the tractor this weekend. Here is what I found. With the tractor completely stopped, if I depress the differential lock pedal with the throttle at operating speed when I depress the hydro pedal it stalls. If I stop the tractor and move the throttle lever down (slow down engine speed) then depress the differential lock pedal, then move throttle lever to normal operating speed, then press the hydro pedal everything functions normally.

Is this standard on a HST tractor? My standard practice for years on my gear drive tractor was to stop movement press differential lock pedal and then move. Throttle setting does not matter on the gear drive Mahindra.

That is messed up, it should function like your old gear drive machine. Im 95% sure even on the fancy electronic HST Grands, the diff lock is purely mechanical, not even a sensor. Throttle position shouldn't make any difference with the diff lock, at least compared to the same response without the diff lock.

 

[5030]

That is messed up, it should function like your old gear drive machine. Im 95% sure even on the fancy electronic HST Grands, the diff lock is purely mechanical, not even a sensor. Throttle position shouldn't make any difference with the diff lock, at least compared to the same response without the diff lock.

I'd inquire with you dealer. Don't sound right to me either but then I don't have a hyrdostat. Mine are gear drive, hydraulic shuttle.

 

[jjp8182]

I spent a little time on the tractor this weekend. Here is what I found. With the tractor completely stopped, if I depress the differential lock pedal with the throttle at operating speed when I depress the hydro pedal it stalls. If I stop the tractor and move the throttle lever down (slow down engine speed) then depress the differential lock pedal, then move throttle lever to normal operating speed, then press the hydro pedal everything functions normally.

Is this standard on a HST tractor? My standard practice for years on my gear drive tractor was to stop movement press differential lock pedal and then move. Throttle setting does not matter on the gear drive Mahindra.

No what you are describing is completely abnormal from my perspective (with my L3560) as I can be stopped (foot off hydro pedal), depress the differential (with my left heel given it's location near base of the seat) and then press the hydro pedal with no issues -- all without touching the throttle (which I usually keep at wide open during operation).

edit: while I don't know that it'd make a difference I also keep the "Auto-Throttle" turned off, and "Stall Guard" turned on

 

[FatTire]

Check out my post on page 2 and 3 of this thread. Philip. https://www.tractorbynet.com/forums/kubota-owning-operating/228484-5740-dif-lock-lever-2.html

Thanks for that info. The thought has crossed my mind many times that Kubota's spring was too strong, but I never really thought about searching for a suitable replacement.

 

[Fallon]

Thanks for that info. The thought has crossed my mind many times that Kubota's spring was too strong, but I never really thought about searching for a suitable replacement.

I only looked at part of that thread... I didn't see what started that spring stuff. But it is quite possible when you stomp on the diff lock pedal you lift yourself out of the seat enough to trip the operator in seat safety sensor. That doesnt jive with your recent experience on the throttle. But could be an unrelated issue making you erroniously correlate other things.

Easy to check. Stand up so there is no weight on the seat & gently hit the go pedal. I forget if my 60 series just stalls or if it alarms first. Safeties kick on if the go pedal is actuated & there isnt any weight in the seat.

 

[greenrider1]

I have an L5740 and use the diff lock quite frequently in the woods. Throttle position should have no effect on its operation, since it's just a mechanical linkage. I engage it mostly when I'm moving, as long as the tires aren't already spinning. On rare occasion I think I have taken enough weight off the seat sensor, which will cause the engine to stall. This is likely your issue if you're on the lighter side. I'm not sure if turning the seat spring down (less tension) would help or not. You could try zip tying the seat sensor switch so it won't disengage and see if that solves your issue. I had to do this running a pto powered backhoe, since I couldn't get out of the seat with the pto engaged.