tis 07 jul 2020, 04:06#654069
Sounds like the hydrostatic system is over-running ie the machine body pushes the hydrostatic motor to act like a pump and that way it starts turning the hydrostatic pump like it is a motor that then starts revving up the engine rpm. And that makes it an evil circle and thee machine goes faster and faster without control except for the "emergency" travel foot brake system. Usually, there is a knob (variable potentiometer/resistor)that sets a cap on max speed. It is a common trick to turn that potentiometer down and that way limits the max speed.
The hydrostatic system has a variable reversible pump and a variable hydraulic motor. The speed increase starts with a pilot prséssure that makes the pump increasing the swashplate angle to its max position. When we demand even higher speed the hydrostatic motor starts decreasing its "swashplate" angle by further increasing the pilot pressure. The potentiometer sets a cap on max pilot pressure so the hydrostatic motor can't decrease its displacement. If this doesn't help turn down the potentiometer even more to limit the pump displacement.
Under normal conditions, the electronic control system should be able to control the speed governed by the engine rpm sensor, but when heavily loaded I steep terrain it's often needed to do the potentiometer trick...
Man lär så länge man undervisar...
//Per A