Shuttle shift operation

[Jay4200]

I've been struggling with my L4200's shuttle shift as of late while running a snowblower. When doing lots of forward and back stuff (like loader work), I generally use the throttle pedal, and chop the throttle while shifting. I also generally take off and reverse in any gear up to about 4 or 5, but typically engage at lower RPMs then stomp on it. Snowblowing pretty much requires me to keep the throttle pinned at PTO+ speed, since the blower will clog up if the throttle is chopped before the blower is clear. Doing parking areas is really tough, as I'm constantly jockying 5 controls (throttle lever, pedal, 3pt, shift, reverser). I'd like to keep the engine WFO and just slam the gear shift and shuttle around, but it seems abusive to jam it into gear when it's revved up like that - seems like I'd be beating on one of the clutches. Am I worrying about nothing, or is my tenderness justified? How much abuse are these things designed for? I don't have a manual handy - what does Kubota say about shifting gears vs. throttle?

JayC

 

[Winmac]

There are two diffrent types or shuttle shifts, from your description i take it you need to clutch in to reverse. It should not cause any problems declutching and reversing at pto speed, if you are having difficlty making the shift it indicates an issue in the clutch.

 

[TripleR]

We have owned two shuttle shift tractors, one with synchro and now one with hydraulic shuttle and always keep it at PTO when running a bush hog. For loader work, I vary the speed.

 

[Jay4200]

There are two diffrent types or shuttle shifts, from your description i take it you need to clutch in to reverse. It should not cause any problems declutching and reversing at pto speed, if you are having difficlty making the shift it indicates an issue in the clutch.

I don't ever have to clutch in. AAMOF, I don't think I've actually ever used the clutch pedal in the 600 hours I've owned it .

I don't know what the reverser and/or gear selector uses for a clutch, or if it even has a secondary hydraulic clutch or if there is some kind of hydrostatic-like gizmo that does the engagements. If it is like a hydro, then there is no issue.

It does delay engagement for a second or two when it is cold, like a hydro does.

JayC

 

[Jay4200]

We have owned two shuttle shift tractors, one with synchro and now one with hydraulic shuttle and always keep it at PTO when running a bush hog. For loader work, I vary the speed.

I don't know what type of shuttle the L4200 uses. There is an hydraulic engagement of some kind, but I don't know if it is just engaging a clutch, or if there is something else engaging the machine.

When running your bush hog, do you shift gears while locked into PTO speed? I assume you don't do much reversing while bush hogging, or do you?

If I just through caution to the wind and shift and reverse at will with the engine pinned the whole time (and use no clutch, since I never do), I could cut my snowblowing time in half.

JayC

 

[colby587]

Hydraulic shuttles are made to take abuse, that's why they are great for loader work. Not sure about the transmission in yours, but on mine there are two clutch packs that are hydraulically actuated, one for reverse, and one for forward. The foot clutch does the same thing as putting the shuttle in neutral. As long as you're not traveling fast you can shift between forward and reverse without stopping or using the foot clutch. Engine rpm doesn't matter as much as your traveling speed. Again, this is for the model I have (m7040) but I would imagine the transmissions are similar.

 

[colby587]

Did some searching, not completely sure but it seems that the GST (glide shift transmission) uses two clutches. One dry conventional type for the foot clutch, and one 'pack' (probably wet) for the automatic hydraulic shifting. The wet clutch pack (like an automatic transmission in a car) should hold up to abuse. I would keep the engine speed where it needs to be and if you need to change directions while going fast just put the shuttle in neutral and slow down with the brakes before going into reverse.

 

[KennyV]

Hey Jay....
Your GST is a regular Gear tractor...
The shuttle and the gear selector both activate a hydraulic clutch pack... it is designed to disengage the clutch pack, Then hydraulic pressure continues to select the chosen gear.. after that the clutch pack engages... It is slow to do this with cold oil because the oil is thick like you figured...
It is Not recommended to shuttle forward & reverse at full engine speed, that is still a big jar to the drive line... you have a lot of stuff spinning and it is not going to like an instant change... Use your foot pedal and you will get into a smooth rhythm, no need to go way down ... but you should drop off enough that it's not a big shock.. The clutch pack is in oil so it is not likely to burn... But it will wear more quickly with abuse, and he pieces end up in the hydraulic oil...

I don't use my foot clutch ether... dry clutch Will wear easily..., I unpinned my foot pedal and locked it down to get it out of the way...
KennyV

 

[TripleR]

I don't know what type of shuttle the L4200 uses. There is an hydraulic engagement of some kind, but I don't know if it is just engaging a clutch, or if there is something else engaging the machine.

When running your bush hog, do you shift gears while locked into PTO speed? I assume you don't do much reversing while bush hogging, or do you?

If I just through caution to the wind and shift and reverse at will with the engine pinned the whole time (and use no clutch, since I never do), I could cut my snowblowing time in half.

JayC

Pretty much what colby587, ours is an M8540 and we pull a Woods DS1260 pull type on pond levies and other places where there are a LOT of direction changes. Yes, I change gears without reducing engine speed.

When changing direction, I do so at a very low speed whether because of being in a low gear or putting it in neutral and allowing it to slow down or by using the brakes.

I have shifted while traveling a little faster than I would recommend when getting acclimated to the tractor, but all that happened was I tore the ground up a bit when the wheels slipped a bit. It is a very durable system.

 

[colby587]

Coming from using large front end loaders for scrap metal handling I probably abuse mine more than I should. I typically will shift withput slowing down in all of the low gears.

 

[Baby Grand]

I have a GST L3240. It has the double wet clutch pack. For loader work and when using the rear blade to plow snow, I use the foot pedal for throttle control. As Colby said, "Engine rpm doesn't matter as much as your traveling speed". This is very true. I've found that lifting off the throttle and stomping on the brakes and coming to a full stop before shifting the shuttle allows for fast reversals. This also works when I'm brushhogging with the throttle set at PTO speed: shuttle into N then hard stop with the brakes then shift the shuttle to the oposite direction and away I go. Works smoothly as long as I'm not in a real high gear.

 

[ccsial]

There is nothing finer than an HST for snow blowing. I could never go back again.

 

[Jay4200]

There is nothing finer than an HST for snow blowing. I could never go back again.

Thanks for the insight. Could I just have your tractor, pretty please?

JayC

 

[Jay4200]

I've found that lifting off the throttle and stomping on the brakes and coming to a full stop before shifting the shuttle allows for fast reversals. This also works when I'm brushhogging with the throttle set at PTO speed: shuttle into N then hard stop with the brakes then shift the shuttle to the oposite direction and away I go. Works smoothly as long as I'm not in a real high gear.

I use the same loader technique with a throttle drop, but you can't do that with a snowblower - learned that the hard way. A few shear pins later, I learned to keep the throttle pinned, but worried about dropping into gear (or shuttle forward/back) with the engine revving. It looks like it's not a problem. Luckily, I don't need to use the brakes while snowblowing - what with the pushing 1000 pounds of blower and snow along the ground, as soon as you pop out of gear, you immediately stop.

How about shifting gears? Let's say your mowing and stop then back up, and say you're in 3rd when you start going backwards, but want to go as fast as you can in 7th. Would you just run the shifter up from 3rd into 7th (maybe hitting 5th on the way) as you began moving and the motor was revving, or would you go back to the pedal and do throttle dumps between gears?

JayC

 

[rbargeron]

I may be missing something here but using the clutch pedal too during higher-rpm shuttles would work better wouldn't it?

 

[Jay4200]

I may be missing something here but using the clutch pedal too during higher-rpm shuttles would work better wouldn't it?

I don't use the clutch pedal - and I don't think using it is a good idea, especially under high RPMs or a heavy load. The foot clutch is a dry automotive clutch. Assuming the glide-shift hydraulic clutch is a wet pack, like a motorcycle, it certainly would take a beating much better than a dry plate.

JayC

 

[rbargeron]

On Grand L's with GST the wet clutch is a 6-plate unit that handles both directions in one hydraulic stack. The dry clutch is a regular automotive plate as you said. In their manuals, Kubota doesn't say why they provide two travel clutches in series on these tractors. It might be they are both needed because neither of them does the whole job under all conditions

Kubotas with the Ever Clutch hyd shuttle didn't have an extra travel clutch. They used the hydraulic for travel and a dry disk for the pto. The Ever Clutch was a large two-stack wet pack with 20 plates. Looking at both designs the 6-plate unit in the GST looks lighter-duty.

Bottom line - high rpm and high load probably aren't good for the GST's wet clutch. It will stand up for a while - the question is how long before a rebuild.

Pages below are from the L4200 operator's manual. They say shuttle at low rpm. (whole copy here.)