2 speed final drive – a common fault.
While technology continues to push boundaries and create efficiency in our hydraulic equipment, it can sometimes have a negative effect on reliability. One such example is now routinely seen by the team in the Plant Parts workshop. About five years ago they started to receive 2 speed final drives for repair that would not shift into high-speed mode, something they had not often seen previously. The operators reported that the machines had no loss of power to the track, but that they were either stuck in low speed or worse, would unexpectedly drop into low speed while on the move.
As time went on we became aware that the problem was getting more prevalent. Ours is the only workshop in the UK specializing solely in repairing and rebuilding final and swing drives and so we have the benefit of experience, repairing and rebuilding many units every week. The problem is almost always caused by the use of certain types of mineral based bio-oils that, unless changed regularly, will degrade to the point where excessive wear can be found in motor casings and other components. That often manifests itself in the two speed control circuit of excavator final drives, where the bore for the two speed piston becomes worn allowing hydraulic oil to pass between the motor case and piston. The effect is that the drive fails to change into high speed or sometimes drops from high to low speed on the move as the machine warms up.
Our dedicated workshop team have developed a fast and effective fix for a fault that now accounts for almost a third of all customer repairs at Plant Parts. However, with so much experience the business understands which excavator models are likely to have 2 speed final drive problems when running with mineral based bio hydraulic oils.
If you are experiencing problems with your 2 speed final drive contact the Plant Parts team for help and advice.
