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03-30-2007, 07:52 PM #11
Re: Synchro vs. Hydraulic m7040
kubota does not label it an "M7040HD" for nothing. The HD stands for heavy duty. The hydraulic shuttle is a HD clutch design with multiple wet discs vs one dry clutch disc. The hydraulic shuttle unit will out last the dry disc style anyday. The price for the hydraulic shuttle is not that much more when you look at the overall cost and life of the tractor!M7040HD W/81" GEARMORE 4G5 REAR BOX SCRAPER/ KUBOTA TNT VALVES/ KUBOTA THIRD FUNCTION FEL VALVE
03-30-2007, 10:21 PM #12
- Join Date
- May 2004
Re: Synchro vs. Hydraulic m7040Originally Posted by 66gladiator
04-07-2007, 12:51 PM #13
- Join Date
- Jul 2001
- Cooke County, Texas
- JD4320 with TNT, electric diverter, cruise control and air suspension seat.
Re: Synchro vs. Hydraulic m7040Originally Posted by machmeter62
"Hydrostatic Drive. 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."
04-07-2007, 08:11 PM #14
- Join Date
- Jan 2007
- Central Lower Michigan
- Kioti DK40SE
Re: Synchro vs. Hydraulic m7040
Two different posters seem to have confused the hydraulic shuttle with a hydrostatic transmission. They are entirely different animals:
-hydraulic shuttle: a conventional GEAR transmission, with the normal clutch replaced with a wet clutch that can be activated by a dash lever without pushing the clutch pedal. There are still individual gears and you do push the clutch pedal for shifting between gears, you just don't push the pedal for shifting among forward, reverse, and neutral. The hydraulic shuttle does NOT have infinitely variable speeds.
-hydrostatic transmission: there is no clutch (most brands except kubota) or if there is a clutch, it is used only for very limited purposes (Kubota). The transmission of power is done by a hydraulic pump/hydraulic motor set up. There are two or three separate gear options that equate to the range options on a gear transmission. Otherwise speed control is done by pushing the HST pedals and varying the amount of power transmitted between the hydraulic pump and hydraulic motor. This allows for infinitely variable speeds, as slow as you want. There is a bit of power loss in the transmission, though it is minimal for most purposes.