drive problem

[fishblood2]

I have an L4330D GST, the gear seem to be engaging but the tractor just dosent have any power, it will move in low gears but wont move at all in high gear or if your moving in a low gear and turn the wheel hard to one side or the othe rit will stop.
Dose anyone have any ideas?
thanks

 

[traildust]

Is the engine staying at the selected RPM when the tractor boggs or is the engines RPM's going down as well?

 

[fishblood2]

the engine is staying the same, when you shift it from forward to reverse it feels like the main cluch is working but like there is something in the GST trans not working. it was working fine yesterday when i was bushhoging but today its not