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Woodham, Ontario | I have never driven with a grain cart, seen a fair number of mostly 7920s in front of grain carts though.
What I have done is driven beside a self propelled harvester with a 7710 with IVT. Works very well, probably the ideal transmission to use for that kind of work. This is how I did it.
When driving to and from the field I just push the IVT lever all the way forward and I have F2 set to 25 MPH. I use the footthrottle to control the speed, just like driving a car. BUT, that doesn't work if you want to maintain a slow speed. You have to pull back on the IVT lever to select a much lower speed and then you can still use the footthrottle to match speed. Just using the IVT lever like a hydro does not work. After you have loaded the cart just push the lever all the way forward and use the footthrottle again to get back to the truck.
The reason you have to select a lower speed on the IVT lever to maintain a slow speed is because an IVT equiped tractor will not accelerate in a linear fashion. It's really odd and I had to play with it for a while to understand it. Basically If you were to set the F2 to 20 MPH at full throttle it will drive 20 MPH, but at half throttle (around 1000 RPM) it will only go 5 MPH. Even when the transmission selector is set to 0 (off). If you press the throttle just a little the tractor will think it can go faster and increase the transmission ratio as well which creates an unusual acceleration. You have no real control over the transmission, it ALWAYS does it's own thing to prevent stalling.
The reason you can't drive it like a hydro is because it responds way to slow. You bump the lever and the tractor realizes you are driving 1 MPH slower than you want and all of the sudden it will try really hard to catch up, by that time you pushed the lever already to far because the tractor didn't respond fast enough.
We owned that 7710 IVT for 18 months and put 1000 hours on it. Traded it because we needed a larger tractor. Demoed a 7720 IVT in novemeber of 2005 and it worked exactly the same.
Drove a Fendt 926 Vario in the summer and it is actually a lot better, none of these issues. You drive it differently, the fendt you just pick a speed, the engine and transmission work together really well. For the Deere it seems the transmision is always a few seconds behind compared to what the engine is doing and then usually overcorrects...
Seems like i'm badmouthing the IVT in this post... It is better for some applications than a powershift, including graincart work, but it is no Vario.
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Is anyone using a JD w/IVT on grain cart?
