Re: 3320 w/ 300CX FEL won\'t lift and Dump??
It took some digging, but here is the story I got. John Deere hooks up the loader raise and dump cylinders so that they are in parallel when the operator tries both functions at once.
The result is that the function requiring the lowest pressure to operate wins and takes all the flow. When lifting and dumping simultaneously, the dumping will get all the flow until the dump cylinders are fully extended, then the lift cylinders can get enough pressure to lift.
Kubota on the other hand put the lift and dump cylinders in series when both functions are selected by the operator. The flow exiting the lift cylinders is then directed to the dump cylinders so that both can operate at the same time.
The John Deere parallel circuit has the advantage when trying to breakout a load by both lifting and rolling back the bucket because the full tractor hydraulic pressure is available to both functions and one will usually move. But when lifting and dumping you have to alternate from one function to the other.
In the same situation with the Kubota, applying both lift and rollback to the valve may not give any results with a heavy load because the lift pressure requirement gets added to the rollback pressure required and that may exceed the relief pressure of the hydraulic system. Then you are forced to alternate between lift and rollback to get full pressure to each.
So, which is better? I guess that's why competition and sales people exist! Each can decide to fit their own needs.
Having operated both John Deere and Kubota tractors with loaders in the past, I have to admit that I never noticed the difference until this discussion came up. The type of jobs that I have done haven't involved dumping and lifting. Usually I just dig up dirt and dump it in a pile. If I want to spread it, I have gotten o.k. at backblading. And I guess I figured out how to get good performance out of both the John Deere and Kubota without thinking about it.
