GST Question

[dieselscout80]

I don't own a GST tractor just researching them.

I have searched about the GST, but I still have a question.

I have used large power shift tractors (JD 4440, CaseIH 7140/7250/8950). With these when under load like pulling a disk or subsoiler and you need to drop down a gear you just pull the leaver to select the gear required without clutching.

I under stand the GST has to be shifted sequentially and it has clutch-less forward and reverse shifts.

My questions is with a GST when under load say like bush-hogging or when pulling a disk and the tractor needs to downshift a gear to avoid lugging can one just move the gear selector from say 4th to 3rd without stopping or clutching?

Carey

 

[David_Kb7uns]

NO, still interrupted power transfer.

Clutch pack is still disengaged with a pause and shifts hydraulically like a standard synchronized gear transmission. You can go from any gear to any gear in the GST but up to 3 servo action can be required for the main, range and aux shift forks in the transmission giving a varied shift time, with an addition timing delay for the feathering of the clutch pack if the engine and transmission have a wide difference in the shaft speeds.

I drive my L3130 GST like a standard transmission in running through the gears above 6 when running on road or carrying loads in loader. I accelerate engine until peaked out, dropping rpm, shifting and going back up on power and it provides the quickest shifting time as the closer the gears are to matching speed the quicker the ECU locks he clutch packs. Unfortunately when under puling conditions or on hills there is still a pause in movement.

A Powershift transmission has 2 clutches and 2 gear sets in constant mesh and alternates between the gear sets using alternate clutches when shifting providing very little pause.

David

 

[countrybumpkin]

I never clutched or stopped mine, I always shifted mine just like any of the larger power shifts I drove.

 

[Fallon]

I drove a pile of big JD PowerShift & Power Quad machines a decade or 2 ago in college. Drove my brothers Father-in-laws L4030 (I think) GST a year or 2 ago... same basic operation & function, but I'm pretty sure the PS machines were dual clutch with nearly instant shifting. Didn't miss a beat upshifting while pulling a disk under heavy load, where tapping the clutch to the floor & letting go as fast as you could was likely to stall the machine. The GST on the other hand is a single clutch & has a 1 second pause or so on shift. I didn't do anything but loader work moving limbs, so can't say on shifting under load for GST. But I suspect you will be disappointed compared to PS machines. Different caliber machines though. The PS machines were well over double the power & price.

 

[Oldoak]

David and Fallon explained the GST perfectly. :thumbsup:

I've owned my L4200 GST since 1997 and my next Kubota will have a GST. No, it's certainly not the equivalent of a PS, but I prefer the GST over Kubota's Hydro. In fact I am currently in the market for a new L5060 GST.

 

[jmc]

Here's my GL4330 manual info on the GST transmisssion. Sorry they are rotated:

 

[dieselscout80]

Ok thanks

If bush hogging and I needed to drop down a gear can I do that without lowering the rpms with the GST, but it will have a slight hesitation correct?

Does the tractor free wheel during this slight hesitation when going uphill?

 

[Peter 315]

Check this out Kubota L4 with Glide Shift Transmission(GST). Demo and Functionality. - YouTube

 

[Fallon]

Ok thanks

If bush hogging and I needed to drop down a gear can I do that without lowering the rpms with the GST, but it will have a slight hesitation correct?

Does the tractor free wheel during this slight hesitation when going uphill?

No need to. It will help prolong the wet clutch life, but they are pretty robust & designed to take it for years.

 

[Willie B]

I don't own a GST tractor just researching them.

I have searched about the GST, but I still have a question.

I have used large power shift tractors (JD 4440, CaseIH 7140/7250/8950). With these when under load like pulling a disk or subsoiler and you need to drop down a gear you just pull the leaver to select the gear required without clutching.

I under stand the GST has to be shifted sequentially and it has clutch-less forward and reverse shifts.

My questions is with a GST when under load say like bush-hogging or when pulling a disk and the tractor needs to downshift a gear to avoid lugging can one just move the gear selector from say 4th to 3rd without stopping or clutching?

Carey

I always prefer LMNO tractors.

 

[David_Kb7uns]

Ok thanks

If bush hogging and I needed to drop down a gear can I do that without lowering the rpms with the GST, but it will have a slight hesitation correct?

Does the tractor free wheel during this slight hesitation when going uphill?

You can downshift no problem, and grab a gear going up, sometimes I will hit the accelerator pedal to boost rpm while mowing to ease the shifting or wait until level or slightly downhill if possible.

Yes if going uphill it will freewheel, if I have to shift up or down on a good hill I will lightly push on the brake pedal to stop rollback so the clutches do not have to overcome reverse movement or excessive speed gain if going down hill.

One very important consideration, IF ENGINE IS SHUT OFF you have no pressure to clutches and TRACTOR FREE WHEELS, so sticking gear shift in gear does no good for holding on a hill and Parking Brake needs to be Engaged and Implements Lowered every time you get off tractor.

David

 

[dieselscout80]

Ok thanks

If bush hogging and I needed to drop down a gear can I do that without lowering the rpms with the GST, but it will have a slight hesitation correct?

Does the tractor free wheel during this slight hesitation when going uphill?

I meant without using the clutch. Sorry for the confusion.

 

[David_Kb7uns]

You just move the GST lever to the gear you want all clutching and shifting is done by the ECU.

The GST ECU box controls the forward reverse shuttle clutches lockup time depending on number of shifts needed, oil temp, speed of tractor and engine speed and then uses pulse width modulation on the solenoid to feather the clutch packs in for the smoothest shifting.

I never use the main foot clutch unless I need to stop everything quickly.

David

 

[Fallon]

You just move the GST lever to the gear you want all clutching and shifting is done by the ECU.

The GST ECU box controls the forward reverse shuttle clutches lockup time depending on number of shifts needed, oil temp, speed of tractor and engine speed and then uses pulse width modulation on the solenoid to feather the clutch packs in for the smoothest shifting.

I never use the main foot clutch unless I need to stop everything quickly.

David

In my couple hours of running a GST doing loader type work I kept using the foot clutch. Force of habit & I didn't have the timing down for the shuttle. I was probably only a couple hours away from re-wiring my brain for it though. At that point you'd never need to ever touch the clutch except as an emergency stop. It clutches automagically using the internal wet clutches for all operations if you use the shuttle lever or gear selector lever.

 

[dieselscout80]

I always prefer LMNO tractors.

What does LMNO mean?

 

[dieselscout80]

I finally found this thread with some good info.
http://www.tractorbynet.com/forums/kubota-owning-operating/49247-gst-transmission-3.html


I guess I didn't search enough. :confused2: