Go BottomL3600 GST and BL4690 question
 | jeffrey
Join Date: Mar 2004 Posts: 0 Monroe WA 
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2001-06-23 29555
I just purchased an 1994 Kubota L3600 GST with a LA682 loader and BL4690 backhoe. My questions concerns both the operation of the GST and an issue with the bh. When shifing between gears, there is a noticeable and uncomfortable delay before the selected gear is engaged properly. It is long enough for the tractor to slow down considerably. Since I have never used a GST before I have little to compare it to. I own an L2850 also, but that tractor has a shuttle shift and will engage as fast as you can clutch and move he gear selector. The L3600 does engage smothly - it just takes it time (2+ sec). I feel like I have little control during that time and I'd hate to be in a situation where I needed a specific gear quickly. I hope someone can shed some light on this. is this an adjustment issue or is something broken in the clutch dept?As far as the backhoe. it seems that there must be some internal leak somewhere as the main boom will sink down and even allow the bucket to touch the ground after a period of say 6 hrs of non-use. Does anyone know what could be causing this? I leave the bh fully retracted and the bucket curled up when not in use. Thanks.
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| Bird Senter
Join Date: Jun 1999 Posts: 962 
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2001-06-25 29609
Jeffrey, I have no personal experience with them, but that delay in shifting is a common complaint with the GST and is apparently normal. From what I've read, the biggest danger is if you try to shift while going downhill, during that pause you may think you have a runaway. ....
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York 
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2001-06-29 29698
You will find that the backhoes will often drop after that period of time. Many backhoes come with pins to lock them in the up position. The glideshift gap is the largest between 4th and 5th gear as it also has to shift the range. From the early tractors to the newest models they have reduced that lag time considerably. To be shifting the tractor at a higher rpm or engine speed will shorten the shift time on the tractor. ....
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| jeffrey
Join Date: Mar 2004 Posts: 0 Monroe WA
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2001-06-29 29705
Art and Bird,
Thanks to you both for the helpful comments. Two things that I found out since I posted this message - Kubota recommends Super UDT Hydralic fluid (the stuff in the tractor is not Kubota)and also I stopped by a dealer who ran a Grand L GST which clealy showed that my tractor is well out of spec. The new machine quickly ran through the gear changes with only slight hesitation -very unlike my L3600.
The 4690 bhoe has several leaks (1 on the dipper cylinder seal and another on the fitting feeding fluid in) so I'm hopeful that if these items are fixed, the creeping will be much less pronounced. Do you agree? For some reason I was concentrating on spool valve pass-thru causing the problem and it did not occur to me that leaks could be attributing to the slow movement of the unit downward as well. ....
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| Les
Join Date: Posts: 1
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2001-12-30 34140
"I" own a "L3600 GST",..The way "I" understand, it's "common" for the machine to hesatate "between" shifts.
You'll get used to it,...... ....
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| JeffreyW
Join Date: Posts: 1
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2001-12-31 34152
Les,
Thanks for the input. By the way, what type of setup (accessories)do you have on your 3600? What do you mostly use it for? Although I like the L3600 for it's power and load handling capabilities, I'm not thrilled about its manueverability and shifting. I've kept my L2850 for that reason. Nice to know that I'm not the only one with the delayed shifting issue.
Anyone else care to comment on their L3600's? or 2850's
Jeff ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-01-01 34174
I'm curious about GST. I knocked around the Kubota site and couldn't find technical descriptions. I wonder how GST works. The site just says it enables 'clutchless shifting.'
What I'm thinking that with a bit of 'educated technique' synchromesh TX's can be shifted quite easily without clutching anyway. Maybe the tricks that I used to drive my old Air Force 1/2-ton around without ever using the clutch could be used to speed the shifting of a GST.
Without getting into details of how a synchromesh works, the general idea is that the speeds of the TX input and output shafts have to be matched for the TX to shift. Clutching gives the TX input shaft independence from the engine, and shifting to neutral gives the input and output shafts independence. Speed of the input shaft can be changed by engine rpm when the clutch is engaged and the TX is in neutral.
The general idea of clutchless shifting is that going to a lower gear means the input shaft has to turn faster in relation to the output shaft. You just let off the gas, bump the TX into neutral, goose the throttle and bump the TX into a lower gear. Shifting up is similar, but the TX is allowed to 'settle' a bit in neutral with the engine at idle to slow the input shaft. Works just fine once you get the hang of it. Some transport drivers say that clutchless shifting actually is easier on some TX's. It’s certainly easier on the clutch.
What ever GST does, it almost certainly has to go through this matching of shaft speed stuff. Of course, the operation is complicated on tractors because hand throttles often are used. Iinput shaft speed can't necessarily be conveniently adjusted with the foot throttle. However, I'm guessing that the GST's delay in shifting results from a need to match shaft speeds. It's just possible that an operator could help speed the process (especially when using the foot throttle) by using the same techniques truckers use to avoid clutching a TX.
....
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