GST Transmission tips or tricks?
- Thread starter npaden
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SkyPup
Elite Member
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- Kubota L-39 GST TLB, Kubota L3130GST, Massey 1030 HST, Kubota ZD-21 ProDecK, Two Euro VW TDIs
Taken from “New Features of the Kubota Grand L30 Series Compact Tractors”
The Glide Shift Transmission (GST) is original Kubota technology which provides 12 forward and 8 reverse shift-on-the-go gears without the need for clutch operation. The GST has a hydraulic clutch and transmission gears that are changed by the action of an actuator located in the transmission. When the operator initiates a gear change, the GST automatically performs a series of operations that includes disengaging the hydraulic clutch prior to the gear change, changing the gears and then engaging the hydraulic clutch after the change.
The ECU allows for a single shifting lever that actuates a potentiometer signifying the specific gear selection. In the Grand L30 series tractors, the ECU controls a proportional pressure reducing valve, solenoid valves, and performs a gear change by operating a hydraulic clutch.
With this GST system the pressurization of the hydraulic clutch can be set by a proportional pressure reducing valve for limitless stages, all of which is controlled by the ECU. The tractor is equipped with an engine tachometer sensor and a travel speed sensor, as well as a potentiometer that distinguishes the position of the gear selection lever. Based on digital signals from the engine tachometer sensor and the potentiometer, travel speed after the completion of a gear change is calculated, while the travel speed sensor calculates the actual travel speed. Based on the difference between the two speeds, the pressurization characteristics of the hydraulic fluid supplied to the clutch is set. Thus the Kubota GST brings about a smooth gear change by changing the pressurization characteristic in response to the various patterns of gear operation.
Acceleration of the tractor is calculated based on digital signals from the travel speed sensor. Under conditions when the tractor accelerates rapidly, the pressurization is changed to become slower during the pressurization process. When the tractor accelerates slowly, the pressurization is changed to be more prompt.
After the hydraulic clutch begins engaging and the acceleration of the tractor starts, the acceleration is calculated and the pressurization characteristic is compensated. Tractors may be equipped with a variety of different implements according the context of work users wish to perform. In particular, when an extremely heavy implement is attached to the tractor, acceleration does not occur until the compensation begins, which makes gear change time much longer. Therefore the compensation of the pressurization characteristic based on the total tractor weight is realized. The offset can be input using the “Adjustment Mode” of the IntelliPanel, with the correct offset stored in ROM. The ECU of the GST takes in the correction value by communicating with the ECU of the IntelliPanel and compensates the pressurization characteristic. The offset is just a derivative of the diameter of the tractors tire diameter.
The Glide Shift Transmission (GST) is original Kubota technology which provides 12 forward and 8 reverse shift-on-the-go gears without the need for clutch operation. The GST has a hydraulic clutch and transmission gears that are changed by the action of an actuator located in the transmission. When the operator initiates a gear change, the GST automatically performs a series of operations that includes disengaging the hydraulic clutch prior to the gear change, changing the gears and then engaging the hydraulic clutch after the change.
The ECU allows for a single shifting lever that actuates a potentiometer signifying the specific gear selection. In the Grand L30 series tractors, the ECU controls a proportional pressure reducing valve, solenoid valves, and performs a gear change by operating a hydraulic clutch.
With this GST system the pressurization of the hydraulic clutch can be set by a proportional pressure reducing valve for limitless stages, all of which is controlled by the ECU. The tractor is equipped with an engine tachometer sensor and a travel speed sensor, as well as a potentiometer that distinguishes the position of the gear selection lever. Based on digital signals from the engine tachometer sensor and the potentiometer, travel speed after the completion of a gear change is calculated, while the travel speed sensor calculates the actual travel speed. Based on the difference between the two speeds, the pressurization characteristics of the hydraulic fluid supplied to the clutch is set. Thus the Kubota GST brings about a smooth gear change by changing the pressurization characteristic in response to the various patterns of gear operation.
Acceleration of the tractor is calculated based on digital signals from the travel speed sensor. Under conditions when the tractor accelerates rapidly, the pressurization is changed to become slower during the pressurization process. When the tractor accelerates slowly, the pressurization is changed to be more prompt.
After the hydraulic clutch begins engaging and the acceleration of the tractor starts, the acceleration is calculated and the pressurization characteristic is compensated. Tractors may be equipped with a variety of different implements according the context of work users wish to perform. In particular, when an extremely heavy implement is attached to the tractor, acceleration does not occur until the compensation begins, which makes gear change time much longer. Therefore the compensation of the pressurization characteristic based on the total tractor weight is realized. The offset can be input using the “Adjustment Mode” of the IntelliPanel, with the correct offset stored in ROM. The ECU of the GST takes in the correction value by communicating with the ECU of the IntelliPanel and compensates the pressurization characteristic. The offset is just a derivative of the diameter of the tractors tire diameter.
After operating my tractor for about 10 hours over the weekend one thing that I notice on my tractor was that the shifting from forward to reverse actually seems to be a little easier when the tractor is still moving slightly. When I say slightly I mean very slightly, wheels are barely moving.
If I came to a 100% complete stop sometimes it didn't want to shift into reverse so I had to move it forward a tiny bit to get it to go into reverse.
Not sure if that is specific to my tractor or if they are all like that.
FWIW, Nathan
If I came to a 100% complete stop sometimes it didn't want to shift into reverse so I had to move it forward a tiny bit to get it to go into reverse.
Not sure if that is specific to my tractor or if they are all like that.
FWIW, Nathan
Muleskinner
Gold Member
I'm starting to have a possible problem with my GST on my L39. Some times if I shift from forward to reverse or from reverse to forward before the engine completly idles down the trans will grind slightly like a bad syncro. Also some times if I shift from forward to reverse there is a short delay before the trans will engage. (Five seconds) Once or twice I have even had to shift the shuttle back to forward and then back to reverse to get the trans to engage. Any ideas? /forums/images/graemlins/confused.gif
SkyPup
Elite Member
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- Dec 3, 2003
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- 3,079
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- Kubota L-39 GST TLB, Kubota L3130GST, Massey 1030 HST, Kubota ZD-21 ProDecK, Two Euro VW TDIs
Be sure to let it hang in neutral for about a second before going into F or R, do not simply go from F->R or R->F.
skyhook
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- 1996 Kubota L4200 GSTC,(sold) 1994 JCB 210S 4x4x4
Just reviving an old thread,
npaden, I have the exact same tractor 1996.
You probably don't have it any longer.
SkyPup, I don't think my 1996 L4200gst has this ECU yo speak of.
johnk
Elite Member
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- western NY
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- Kubota GST Grand L3130 w/ 723 loader, Ags
I have a 3130 GST 2008 over 500 hours and no problems.........
