Mowing linked pedal question

[PA hayseed]

This NX HST CAB is new to me, so here it goes:

It has been raining for weeks, finally getting a chance to cut a field with the new tractor. Had the rpm speed up high (after starting mower), had linked pedal on, 2 wd, and PTO on for 7' RFM (it is cool out so there is no AC on). The tractor would surge and bog down occasionally, is this normal for the linked pedal operation? Previously if I saw high heavy wet grass in front of my old DK, I would just slow the tractor speed down and cut it. I tried to slow the tractor down with the hst pedal, but sometimes it would seem to surge forward. It definitely bogged down a bunch of times.

Looking for tips or input. TIA

 

[CMV]

You can't do linked pedal with PTO engaged.....well you can, but won't keep PTO RPM steady. Linked pedal just for transport, loader work.

 

[Will_C]

I'm guessing linked pedal is similar to the auto speed function on my Kubota Grand L. It makes the engine speed up to match the depressing of your hydro pedal. When you are mowing, you want a steady engine speed, and you control your ground speed with the hydro pedal. In thick grass or rough terrain, you may have your engine running to keep your PTO at 540rpm, but only slight pressure on the hydro pedal to go say, 2-3 mph. Hope this helps.

Will

 

[Overtaxed]

Mine sounds similar if I I used linked pedal with a bush hog. I'll lay off the hydro and the tractor will surge a little sometimes. I suspect its because the engine is trying to slow down (in response to the pedal being released) but the PTO is "pushing" it forward and the hydro winds up overrunning a bit. I can feel it, but it's not a big "surge", it's a lurch. So it might be normal what your feeling depending on how big the surge is?

Running my 6' bush hog, I usually disable the linked pedal and set the RPMs at around 2K. I don't need full power to mow effectively, the tractor is quieter and I'm sure it's less fuel to mow a bit below full PTO speed.

 

[DieselBound]

Might be the anti-stall that's the culprit? This function is meant to cut back on auxiliary functions' performance in order to keep the engine from stalling out.

I don't like the linked pedal operation at all. I find that it causes the engine to too readily race the RPMs.

Maybe what you're wanting to do is to set cruise? Not sure if anything different. Bottom line is that if you're pushing through material that is causing your tractor to bog down, well, your tractor is going to bog down! (time to back off the speed and allow the cutter to operate at full speed)

 

[finn1]

As previously stated, linked pedal is for transport or situations where you want to control engine rpm with your foot.

The regular isochronous governor is for pto work where you want the pto to run at a constant speed, eg bush hog work.

 

[Threepoint]

This NX HST CAB is new to me, so here it goes:

It has been raining for weeks, finally getting a chance to cut a field with the new tractor. Had the rpm speed up high (after starting mower), had linked pedal on, 2 wd, and PTO on for 7' RFM (it is cool out so there is no AC on). The tractor would surge and bog down occasionally, is this normal for the linked pedal operation? Previously if I saw high heavy wet grass in front of my old DK, I would just slow the tractor speed down and cut it. I tried to slow the tractor down with the hst pedal, but sometimes it would seem to surge forward. It definitely bogged down a bunch of times.

Looking for tips or input. TIA

PA hayseed, assuming that you already had the rpms high with the hand throttle, I'm fairly sure that having "Linked Pedal" engaged didn't cause this. The surging and stalling sounds like what happens when the tractor just bogs down, e.g., when in high gear trying to climb too steep a hill. To rule it out, if you haven't already tried, disengage Linked Pedal and see if you can duplicate the condition while mowing.

On my NX4510HST Cab and CK3510SE HST, increasing the rpm with the hand throttle simply overrides the Linked Pedal function if it's engaged. BTW, I disagree with comments that Linked Pedal is only for transport and loader work. It's good for transport, yes. But it is also good for ground engagement work. I use it all the time for grading with a box blade filled with wet stone, and moving heavy snow with a rear blade. By contrast, it's not good for loader work with a bucket or a grapple. Continuous high rpms are needed for the hydraulic flow used for lift/lower, roll-back/dump, open/close. So if you are operating with Linked Pedal engaged, you have to throttle up with the hand throttle anyway, each time you perform those functions. As you know, Linked Pedal increases rpm only in response to HST pedal use.

Please report back after you finish investigating.

 

[PA hayseed]

Thank you to all that replied. I need to do some more "experiments" to get a better understanding of this function. I need to remove variables, so that I ensure I get accurate results. I may have had the anti stall on, I am not sure, as the very first thing I did when I got the tractor was start using the loader on a big ole dirt pile. I will check back in once I get some quality seat time.

The cab gets really hot. I have to make some adjustments to how I operate this tractor compared to the old one. One annoying safety feature I cannot stand is the tractor switching off when I get up off the seat. I was so used to dropping the bucket and rear attachment, put on parking brake, and jump off the tractor. I would do what I needed to do, then get going again. Adjustments to my routine. THe cab also prohibits me from just jumping on and off (last tractor was open station). THe other thing I used to do is when attaching threepoint equipment, i used to stand to the side of the tractor and bump the pedal forward or back to line things up, cant do that anymore (I know safety violation). It seems harder to line up the hookups now, as I can't just turn around and look down.. ON the bright side the AC was chilly the other day and I had to turn it down to keep warmer. I can't wait to move snow this winter in a heated cab, no more snowman in 7 layers of clothes.

 

[DieselBound]

Again, look in to how the anti-stall works. But, as noted, one can bog down any tractor.

 

[PA hayseed]

**Update** NX50 hst cab

SO I made sure that linked pedal was off, that anti stall was off, and that everything but the PTO was off (except for the AC this time as it was about 90 today). Cut grass for about 4 hours, and here is what I noticed:

The tractor did not bog down or slow down this time, but the grass was pretty dry. THe tractor did surge/jerk forward several times. It is like driving a stick and kind of clutching where you get that surge forward then slower. After this happened the first time I made sure that I kept my foot pretty steady on the pedal, it took awhile but it happened again. Is this normal for these new tractors? THis is an HST so it isn't like I'm riding a clutch. It was almost like it was going to catch a higher gear then didn't.

THe other odd thing I noticed is when I would back up (with pto running) to cut around something, when I pushed the forward pedal again nothing happened. SO, I pressed the rear pedal again, then the front and it would move forward then. I got into a bind where I couldn't back up any further by a tree, and the only way I could get it to go forward again was to depress the brake pedal for about a second or two then it would go forward. Is this a new feature on the HSTs? IF so I really hate it. My last tractor was super sensitive, back forward, it would just go. I became very accustomed to this movement and I don't like the way this one is working. Maybe it needs an adjustment.

Any ideas or tips? I have no way to know if this is normal or not for these NX's.