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Wi | CVT's are simple, the ones in farm tractors all follow a similar principle. They use a power split device (the planetary) to mix hydraulic drive with mechanical drive. Power takes the past of least resistance which is what makes the PSD work. Its how a prius works too. On the Fendt, the planets are always turning with the engine, put resistance on the ring gear and power will go through the sun gear, put resistance on the sun gear and power will go the ring gear. The ML260 Fendt CVT is tiny, very tiny for what it does. Since there is never a shift, the parts don't need to be built heavy because they never encounter a shock load. Fendt's claim to fame with their CVT and what their patents protect is the swing angle of their pump and motors. That is what allows them to go through the entire speed range with no steps and have smooth reverse with no shifts. The other CVTs require shifting of clutchpacks through the range to achieve the full range of speed. CNH's popular trans from Steyr uses 4 IIRC, Deere IVT in the bigger tractors uses 2 IIRC. You will also notice how much larger and heavier they are built to withstand the shifting. The clutchpacks add a wear point to the trans, whether or not its actually an issue though I can't say. There is something to be said about a CVT with multiple ranges. At certain speeds in the CNH trans you will have the transmission itself in a more mechanical state than the Fendt trans. How much this benefits you, I don't know. In theory it should. As with anything there are tradeoffs. The Fendt trans is good and has proven itself, I am not going to say it is indestructible and everything else is inferior though.
there isn't any way to monitor really where the transmission is at. It's not really a big deal though, just run it in DTM mode and you will always be operating as efficient as possible. The DTM mode is similar to the TMS mode in a Fendt but without the "Auto" function. You pick the percentage it can lug the motor down and it will do the rest. You can also set minimum RPMs and Maximum RPM's if you wish. Generally what I've seen running our DT275B (Tier 3 8680) that we had and our current Tier 4 8680, the RPM's generally don't go much below 1400-1500. I always set them to lug 12% which brings it down to the engines peak at 1850. Some people go a little lower yet. Whatever RPM's you set it to pull the engine down to will end up being the max RPMs because it wont have any reason to rev the motor higher. Fendt's auto mode just adjusts the transmission and engine even further according to the conditions. I planted 90% of our rye under 1100rpm this fall. MF's DTM mode will still save you a ton of fuel though and make operating the tractor easy and enjoyable.
It takes a little while for people who are new to the DTM/TMS concept to get used to the "butt" feeling of low RPM's. A lot of people are used to older tractors where you set the throttle up and as the tractor worked you heard it pull the throttle down and "felt" like it was working. With DTM/TMS the engine never rev's up past where its set to lug to and it just increases the load on it as needed. You can feel the engine work a bit harder even if the RPM's aren't changing, but many people "think" the CVT's don't put power down because of the illusions they play on your "butt dyno". Many people also don't feel like they are going that fast down the road when the RPMs are sitting down at 1500 or so because they are used to full throttle on the road. It takes awhile for your butt dyno and other senses to get adjusted to the feel of the CVT along with the DTM/TMS style of operating, but once you do you will love it.
Its up to you whether you want to run it with the pedal or the stick. When in DTM mode you simply push the stick forward to speed up and pull it back to slow down, the tractor automatically adjusts the engine speed as needed. There are 4 levels of acceleration that can be programmed for the stick, pedal, cruise speeds and reversion response. These are accessed through the displays on the MF machines. The max speed for the pedal can be adjusted with the scroll wheels, this will rescale the pedal for whatever top speed you set it at. It will not effect the top speed of the tractor. Say you want the pedal at 10mph max for driving next to the chopper but have a 34mph cruise setting, you can run the pedal with its max speed of 10mph for better control, but if you hit the 34mph cruise button it will resume that speed. When you let off the pedal the transmission will decellerate similar to a hydro but a little less agressive. I like to use the pedal when driving around and use the cruise setting for the road and for field operations. We spend a lot of time on the road so this works well, for row crop farming I could see why more people just choose the stick.
If you run something on the PTO and need constant speed, one very important thing to remember on the MF's is that unlike the Fendt, when in pedal mode, if you move the hand throttle it responds as if you are operating the foot pedal. Don't ask me why, but it will scare the crap out of you the first few times you accidentally do this. If you still want pedal mode for driving around in the field with say a grain cart but need say 1800RPM for unloading, just program that RPM into the A or B buttons, then when you get up to the truck to unload just hit the button and the engine will go to that speed and you can still use the pedal to control the transmission to inch your way along the truck. Then hit the button again to cancel the speed. One extra step I find annoying on the MF is that you have to hit the DTM button after you use a preset RPM. It does not automatically go back to DTM mode. This may change with some software updates, but last I knew it was still this way for some reason.
One nice advantage to the Fendt CVT is that you can limp it home. The 8600s were know to blow some lines internally on the hydro pump which would cause a loss of hydraulics (not the steering though). This leaves you stranded with the parking brake locked. In situations like this, the CVT can limp you home as it requires no hydraulics from the tractor and no electronics are needed to make it operate. You have to manually release the parking brakes from behind the cab, then start the tractor in limp home mode by holding the button, then insert the limp home handle from behind the cab through the floor. Then twist is to speed up or slow down. Pretty simple. The CVT being seperate from the auxillary hydraulics reduces contamination. If you get an 8600 remember the dipstick/fill hole at the rear is the transmission. The hydraulic reservoir has a gauge in the cab and is filled from the top of the right side fuel tank. Take the panel off where the battery is and the fill cap is there. Fendt is the same way, they want you to pump fluid in through a remote so it gets filtered otherwise you fill through the breather on the left side in front of cab under hood.
Most of the electrical gremlins with the 8600s that we experienced didn't really shut you down, they were just annoying. There were a few big hydraulic ones but otherwise just leaks. There is a new coupler that should fix most of those issues though. The Tier 3 machines went through DEF sending units a lot. The Tier 4 machines did away with that system. Light control modules loved to fail on all of them and do some funky things when they act up.
Overall though they are much better now than when they came out, and Agco does actually listen to the problems that the techs bring up and tries to come up with a solution. A lot of their issues stem from the stuff they outsource. They don't seem to have as good of a stranglehold on their supplies like Deere, Cat and other big names do.
Don't think they are a terrible tractor though, I just try to give an honest review. I could just say they are the worst tractor ever due to how much our DT275 was broke, but its clear it was a lemon and also a very early model too. I don't believe in sugar coating things either. I like our Fendt a lot better but it too has broken three times in the 500hrs it now has on it. We got it in september with 160hrs. One small external hydraulic line got a hairline crack, the air line going to the air compressor governor came off and it just came back from its 500hr service and also had to be fixed due to a DEF error code and derate. I did not get a chance to find out what they fixed on it though but it wasn't down long. The bottom line is that no matter what you buy, its going to break and need a dealer to fix it at somepoint so make sure you buy something you can get some service on. A lot of people talk about Deere resale, thats great, but your buying now, the savings on an MF are big and theres a bubble ready to pop in the used market for Deere IMO. lots of machines out there, low corn prices and many smaller guys took advantage of the higher prices the past couple years to upgrade their equipment and now they are set for awhile.
What general area are you located in? Do you have decent MF service there? | |
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Massey Ferguson 8680 advise and opinions wanted
