TBarD
Silver Member
- Joined
- Mar 5, 2012
- Messages
- 183
- Tractor
- Kubota M59
Well you could actually have a HST problem, but the symptoms suggest it may be a simpler (and much less expensive) electrical problem instead, so that would be the first thing to look for. The ECU (computer) controls everything. The HST pump is directly connected to the engine via the clutch. Flow to the HST motor is controlled by a servomechanism that is controlled by the ECU. When you move the foot pedal the ECU is sending signals to the servo which moves a swash plate. The swash plate controls flow to the HST motor, providing forward or reverse and speed control, all by controlling the flow of hydraulic oil. The bottom line is, probably either the ECU is not saying go for some reason, or (less likely) you could conceivably have a problem with the HST servo. The first thing to do is check for error indications from the ECU, after which you would have to start running diagnostic tests.