Shuttle shift operation

[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.)