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  1. #11
    Silver Member
    Join Date
    Nov 2003
    Posts
    220
    Location
    White Co., ARKANSAS
    Tractor
    Kubota L3830 DT & B2710

    Default Re: FST vs GST vs HST

    I have an L3830 w/ manual trans - FST. I've owned it for 3 years.
    I think the GST would have many advantages over the FST.
    Here's what I beleive to be some GST advantages:
    -12 forward gears as opposed to 8 on the FST - this gives additional range of speeds for various tasks.
    - no clutching between gears
    - no clutching required for shuttle
    - no stopping required to shift between high & low ranges
    When bush hogging, I often need to shift between 4th (4 lo) and 5th (1 hi) - so I have to come to a complete stop, clutch, shift from lo to hi range, shift to 5th, release clutch, go.
    I'd rather have the GST!
    Hope this helps.
    JLOAF
    Kubota L3830 DT
    723 FEL
    Kubota B2710 HST

  2. #12
    Silver Member
    Join Date
    Jun 2001
    Posts
    179
    Location
    Northern Minnesota
    Tractor
    Kubota and John Deere tractors 20-40HP; skid steer loader

    Default Re: FST vs GST vs HST

    Do I understand correctly that you have to either shift to neutral or clutch to stop the tractor with GST (unlike an automatic trans on a car which can be stopped in gear)?

    Danny

  3. #13
    Veteran Member DUMBDOG's Avatar
    Join Date
    Jul 2002
    Posts
    1,068
    Location
    Central ND, Central FL
    Tractor
    NH 1630 W-7308 FEL/ Kubota L4630GSTC W-LA853 FEL WQ/A-CC 2544

    Default Re: FST vs GST vs HST

    Quote Originally Posted by dannyk
    Do I understand correctly that you have to either shift to neutral or clutch to stop the tractor with GST (unlike an automatic trans on a car which can be stopped in gear)?

    Danny

    That is correct, the tractor will keep pulling as long as it is in gear. You must put it into either neutral on the forward/reverse on the column, neutral with the gear selector or disengage the clutch.

  4. #14
    Elite Member SkyPup's Avatar
    Join Date
    Dec 2003
    Posts
    3,005
    Location
    North Central, Florida
    Tractor
    Kubota L-39 GST TLB, Kubota L3130GST, Massey 1030 HST, Kubota ZD-21 ProDecK, Two Euro VW TDIs

    Default Re: FST vs GST vs HST

    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.
    Suck, Squeeze, Bang, Blow......GO Diesel GO!

  5. #15
    Silver Member
    Join Date
    Jun 2001
    Posts
    179
    Location
    Northern Minnesota
    Tractor
    Kubota and John Deere tractors 20-40HP; skid steer loader

    Default Re: FST vs GST vs HST

    In spite of the complexity of the GST, I have the impression that the transmission is relatively reliable. Is there anyone out there who would not recommend the transmission because of reliability issues?

    Danny

  6. #16
    Elite Member SkyPup's Avatar
    Join Date
    Dec 2003
    Posts
    3,005
    Location
    North Central, Florida
    Tractor
    Kubota L-39 GST TLB, Kubota L3130GST, Massey 1030 HST, Kubota ZD-21 ProDecK, Two Euro VW TDIs

    Default Re: FST vs GST vs HST

    Quote Originally Posted by dannyk
    Is there anyone out there who would not recommend the transmission because of reliability issues?

    Danny

    Not me, I only have two of them, but be sure to only use SUDT or SUDT compatible hydraulic fluids, your proportional reducing valves will thank you for it!
    Suck, Squeeze, Bang, Blow......GO Diesel GO!

  7. #17
    Silver Member
    Join Date
    Nov 2006
    Posts
    135
    Location
    Napa, Ca
    Tractor
    2006 Kubota L3830

    Default Re: FST vs GST vs HST

    SkyPup-

    Thanks! Now I think I can finally understand the theory of operation behind the GST

  8. #18
    Elite Member SkyPup's Avatar
    Join Date
    Dec 2003
    Posts
    3,005
    Location
    North Central, Florida
    Tractor
    Kubota L-39 GST TLB, Kubota L3130GST, Massey 1030 HST, Kubota ZD-21 ProDecK, Two Euro VW TDIs

    Default Re: FST vs GST vs HST

    The main problem with HST or GST transmissions is not with the transmissions, instead it is with the people that fill them up with cheap straight hydraulic fluids thinking that they will save some money on consumables...... ---->>>> BIG MISTAKE! .
    Suck, Squeeze, Bang, Blow......GO Diesel GO!

  9. #19
    Veteran Member
    Join Date
    Jun 2003
    Posts
    1,649
    Location
    Northern, New York
    Tractor
    Kubota L3830 03: RTV 900

    Default Re: FST vs GST vs HST

    I have a GST and I do not have to use the clutch unless I want to. I can change directions with no clutch. I can up shift gears or downshift with no clutch. The HST takes approximately 4 to 5 HP away from your PTO HP, Where as with the FST and GST it does not. AN HST will use more fuel in 8hrs of loader operation that a GST will, but the HST will do loader work faster.
    M-5040 w/cab, 05 RTV 900, Where the maple sap flows

  10. #20
    Super Member
    Join Date
    Sep 2000
    Posts
    6,553

    Default Re: FST vs GST vs HST

    Quote Originally Posted by dannyk
    Do I understand correctly that you have to either shift to neutral or clutch to stop the tractor with GST (unlike an automatic trans on a car which can be stopped in gear)?

    Danny

    Unlike a car, there is no torque converter to allow the rear tires to stop while the engine is turning. It's not an automatic at all, it's more like a hydraulically shifted manual transmission. (How's that for a condensation of Sky's wonderful explanation?) As such, when in gear with the engine turning, the tires are turning.

    The GST and the HST are both dead reliable.

    Pretty much if a Chevy is like a rock, a kubota is like an Anvil. (only tougher)

    jb

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