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  1. #1
    Silver Member
    Join Date
    Oct 2004
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    133
    Location
    New Jersey

    Default Shuttle shift

    Hello all,
    I'm new to this site and I've been looking at buying either a new or used compact or utility tractor and my questions relate to transmissions. Can some explain to me how a shuttle shift transmission works. Is there a clutch, a gear shifter, etc.? Also, what is the technical name for the type of transmission that allows you to choose from different ranges (i.e. high, low, low-low, etc.), but has a shifter (mounted somewhere around the steering column) that is marked: "F", "N", "R"?

    Thanks
    Ryan

  2. #2
    Veteran Member
    Join Date
    Jul 2001
    Posts
    1,076
    Location
    Cooke County, Texas
    Tractor
    JD4320 with TNT, electric diverter, cruise control and air suspension seat.

    Default Re: Shuttle shift

    Here is an excellent review of transmissons from TractorSmart :

    "Manual Shift. Also called straight shift. The Massey Ferguson folks, over in England, refer to this as a crash shift gearbox. That's a pretty good name, because that is (more often than not) exactly what occurs when you try to shift on the go. The two gears that you are attempting to mesh are rotating at different speeds, causing that grinding noise you hear. The two most popular styles of manual shift transmissions are the sliding gear, and the collar shift. In the sliding gear style, the gears are splined to the main shaft, and gear selection is made by actually moving the gears, via shift forks, into the appropriate location. For the collar shift style, the gears are built up into a stack. The gears do not slide back and forth. These gears are not splined to the main shaft but are free to rotate when not engaged. There is a shift collar in between each gear pair, i.e. 1st & 2nd or 3rd & 4th. This collar is splined to the main shaft, and is the movable component when a speed change is called for. Manual shift transmissions, while not as user-friendly as some of the other types, tend to have cast iron durability.

    Synchro-Shift. Essentially a collar shift transmission, with the addition of synchronizers, which allow for crash-less shifting on the go. In order to achieve a smooth shift, the first thing that must happen is an equalization of rotational speed of the gears that you wish to bring into mesh with each other. This is the chief function of the synchronizer. Let's suppose our transmission is synchronized between 3rd and 4th gears. We'll start out in 3rd gear, and then shift into 4th. As we shift, the first occurrence in the chain of events is that we move the transmission out of 3rd gear, and into neutral. As we continue moving the shift lever towards 4th gear, a brass cone applies friction to 4th gear, increasing or decreasing it's speed to match that of the rotating collar. Once the speeds have equalized, the gears still may not be lined up with each other, so there are little triangular shaped teeth around the outer circumference of the brass cone, which serve to ever so slightly rotate the shift collar teeth and the gear teeth into perfect alignment. This whole process occurs rapidly, usually allowing a straight-through shift, directly out of one gear and into the next. Synchro transmissions range from simple, where only a single pair of gears are synchronized, on up to full synchronization of all speeds, including forward and reverse. Shuttle-Shift, which refers to synchronization between forward and reverse, is a real benefit to have on a tractor that will be used for front loader work. Still a reliable transmission, but a little more subject to failures because of the extra bearings, synchro rings, etc. that are in use. More complex = more potential for failures to occur.

    Power Shift. Has a lot of similarity to the collar shift, in that the gears are in constant mesh. Instead of a sliding coupler, there is a clutch pack, that when energized, causes the selected gear to rotate by locking it to the main shaft. Some, or all, of the speeds in a given transmission may be selected via the power shift method. However it more often the case that only a portion of the speeds are selected in this manner. This usually results in a hybrid, synchro-shift/power shift type of transmission. Power shift gives you the ability to select several different speeds while on the go without having to use the clutch pedal. When everything is working properly, they are really nifty to use. Beware of poor maintenance habits, though. Neglecting to change the transmission oil and filters, as recommended, will result in this transmission biting a big chunk of money out of your wallet.

    Hydrostatic Drive. There is nothing new-fangled about this transmission. It has been around for a long time. Nevertheless, it is among the least understood of all transmission types. It is common for it to be compared with the automatic transmission in an automobile. They are different animals altogether. The only similarity is that they both use oil to transmit power. Tech types describe a hydrostatic transmission as being a variable-displacement hydraulic pump, driving a fixed-displacement hydraulic motor. Now, to the un-initiated, that's a bunch of gobblety-gook. So let's s t r e t c h that explanation out a little bit. Any hydraulic pump's sole purpose in life is to deliver some amount (volume) of fluid to some other device, which in turn moves whatever is attached to that device, causing work to be performed. This can be either through linear motion (as in a hydraulic cylinder), or rotary motion (as in a hydraulic motor). If we want to control how quickly our device moves (or rotates), one way we can do that is to vary the amount of oil that the pump sends to it. If our pump is delivering four gallons a minute, things will happen four times faster than if we only pump one gallon a minute. (Are you with me, so far?) Since we can control our pump's output, we can control the motor's speed. Now, unless we just want to go around in a circle all day long, we've got to figure out how to change directions. No problem. (You knew that, didn't you?) Most hydraulic motors don't care whether they are turned clock-wise or counter-clockwise. (They probably don't even know the difference!) Since a hydrostatic transmission operates in what is called a closed loop system, consisting of the pump and motor units, we simply reverse the direction of flow from the pump, causing the motor to operate in the opposite direction. Oh, by the way, closed loop means that a fixed amount of system oil is trapped, or contained, within the pump/motor circuit. Assume that a certain hydro transmission is of a size that it contains 500 ml of oil within the closed loop. That volume remains constant, never changing regardless of tractor speed or direction. So, for any change that we make in the output volume and/or direction of flow of oil from the pump section, a reaction must occur in the motor section, inducing a corresponding change in motor speed and/or direction. In reality, there is a certain amount of oil that is constantly escaping from and being replenished back into the closed loop section of the transmission. This is because a small amount of oil is allowed to flow all around the various components for lubrication and cooling purposes. The greatest advantage of a hydrostatic transmission is the ability to infinitely vary the ground speed and quickly change directions. It's like having a million speed transmission. If you need a travel speed of 1.200589 MPH, it is available. Another advantage is reliability. This transmission is, by way of design, pretty much self-protecting from operator abuse. Also, on foot pedal controlled transmissions, there is a built in safety factor in that you need only lift your foot from the pedal, to bring the tractor to a controlled stop. The only disadvantage of note is a slight loss of power at the PTO shaft. You must also remember to apply the parking brake should you park the tractor on a slope. Hydrostatic is, by far, the best choice for turf mowing applications or for any tasks that require constant speed and direction changes within a small area.

    Glide Shift. This is a kubota exclusive. It is best described as a manual shift transmission whereby gear selection is achieved without the necessity to operate the tractor's main clutch. It is very similar in design and function to the synchro-shift type. All of the gears in this transmission are synchronized. The major difference is found in the addition of one hydraulic clutch pack and a hydraulic shift cover that is mounted to the side of the transmission housing. Eight speeds are available, with forward and reverse (shuttle) for each speed. Stay with me as we go through a shifting sequence. Let's assume that we are in 2nd gear and wish to shift into 3rd. Without touching the clutch pedal, we simply move the shift lever from 2nd gear position into 3rd gear position. (Boy, that was easy!). What just happened was, we lined up some oil passages in the shift cover to redirect pressurized hydraulic oil to make the shift for us. The first thing that happened was that the hydraulic pressure that was holding the clutch pack squeezed together was allowed to escape, releasing the clutch. This causes the engine to stop driving the transmission. Next, oil (under pressure) is directed to the 2nd gear shift rail cylinder in a manner which places that rail in neutral. Then, oil pressurizes the 3rd gear shift rail cylinder to move 3rd gear into engagement. Oil is then directed to the clutch pack squeezing it together once again, to reconnect engine drive power to the transmission. The actual shift part of the sequence occurs very quickly, taking about 4/10ths of a second. Clutch pack re-engagement, however, is a time-controlled process in order to allow smooth shifting and eliminate jerkiness in the shifting process. Glide shift has been around for several years now with excellent reliability. It is a great choice if you will be doing a lot of front loader work, as well as working in larger fields. Using a front loader can be very hard on main drive clutches. With glide shift the need for manual clutching is eliminated, thus saving wear and tear on the clutch as well as your leg!"


  3. #3
    Bronze Member rebelmedic's Avatar
    Join Date
    Aug 2004
    Posts
    71
    Location
    United states,South Mississippi
    Tractor
    New Holland TC48DA

    Default Re: Shuttle shift

    My TC48 has a shuttle shift with the lever as you speak about. There are several types of shuttle shifts. Manual,syncronized, and electric assist. Manual requires clutch to be pushed in and full stop before shifting directions.Mine is syncronized requireing the clutch to be pushed in before shifting from one direction to another but, the tractor can still be moveing.Electric assist does not require clutch to be pushed or movement stopped. Only requires a very slight(couple of seconds) delay between shifting directions with out useing clutch. The post above was done while i was writeing this one and covers it much better

  4. #4
    Silver Member
    Join Date
    Jul 2004
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    236
    Location
    Escondido California
    Tractor
    2005 Ingersoll Rand Bl370b

    Default Re: Shuttle shift

    Thanks for sharing this artical on transmissons it was very informative. David

  5. #5
    Silver Member
    Join Date
    Oct 2004
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    133
    Location
    New Jersey

    Default Re: Shuttle shift

    Thanks for the all the detailed info. Now, if I was to buy a tractor, what would be the best type of transmission to get. I plan to do some loader & backhoe work, plus snow removal, grading, etc.

    Thanks
    Ryan

  6. #6
    Platinum Member
    Join Date
    Mar 2002
    Posts
    718
    Location
    Maine
    Tractor
    Cub Cadet 7360SS & Craftsman GT3000 23 HP w/50

    Default Re: Shuttle shift

    Ryan, around here that is just a volatile question as asking which tractor brand to buy. Try out both and decide for yourself. I wouldn't trade my gear/SS for anything. Although many would tell me that I should have hydro because I do a lot of FEL work. But then, I drive a Ford too. [img]/forums/images/graemlins/grin.gif[/img]

  7. #7
    Super Star Member RoyJackson's Avatar
    Join Date
    Nov 2001
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    18,831
    Location
    Bethel, Vermont
    Tractor
    John Deere 4400 MFWD, Deere 855D UTV, Z920A Zero Turn Mower and assorted implements

    Default Re: Shuttle shift

    </font><font color="blue" class="small">( Thanks for the all the detailed info. Now, if I was to buy a tractor, what would be the best type of transmission to get. I plan to do some loader &amp; backhoe work, plus snow removal, grading, etc.)</font>

    That depends on you!
    I'm a gear guy...but mostly because I won't spend the extra $1500-$$2500 for a hydro tranny. Gears serve me well.
    You could easily go gear if you want to...based upon your description of your tasks.
    I bought a 790 Deere because it's the right sized and HP for any tasks I see at present and the future. I got a very good deal on a very nice tractor. If it had been a hydro machine....I'd of still bought it.

    So, you can do all your tasks with gears, but do you want the convenience of hydro?

  8. #8

    Join Date
    Dec 2004
    Posts
    303
    Location
    Amelia Va.
    Tractor
    John Deere 790wFEL

    Default Re: Shuttle shift

    A good compromise would be shuutle shift, Very convienent and you dont loose the power you do to a hydro.The loss to hydro is minimum,but also has a different feel or reaction to the operator.You will just have to feel the difference for yourself.Alot of guys have made an excellent point about hydro being much easier on the knees when doing alot of work.If that could be an issue for you, then look hard at the hydro.

  9. #9
    Platinum Member
    Join Date
    Sep 2004
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    929
    Location
    Bloomington, IN
    Tractor
    Kubota, G5200, KAMA 454

    Default Re: Shuttle shift

    Creeper,

    I agree. thay is why I chose the KAMA 454 with the shuttle shift. One lever, Forward/reverse. On my kubota lawn tractor, I lilke the HS.

    Patrick

  10. #10
    Platinum Member
    Join Date
    Sep 2004
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    929
    Location
    Bloomington, IN
    Tractor
    Kubota, G5200, KAMA 454

    Default Re: Shuttle shift

    Creeper,

    I agree. thay is why I chose the KAMA 454 with the shuttle shift. One lever, Forward/reverse. On my kubota lawn tractor, I lilke the HS.

    Patrick

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