oldnslo
Super Member
John,
at 300 hrs is this still under warranty?
Not sure of your mechanical and or electrical skills but a good service manual should show the diagnostic steps or procedures for trouble shooting the HST drive - control. (I have no clue how good or bad MF manuals are) There are two or three main styles of control. Smaller tractors typically direct mechanical control. Very simple to trouble shoot since linkage directly moves the swash plate for directional control. Usually seen on SCUT and CUT.
Another control type: hydro-mechanical where mechanical linkage from treadle pedal operates a control valve assembly that directs pilot pressure to the control piston for the swash plate. Pilot pressure comes from charge circuit. On these there are typically test ports where you take pressure readings to diagnose what is going on. Usually fairly straight forward diagnostic procedure.
Other control type: electro-hydraulic where a variable amperage is applied to a proportional coil on the HST control module for directional control. These have some form of variable signal from the treadle peddle that is input to some form of electronic controller which then outputs the milliamp signal to the coil. On these there could be test ports for monitoring control pressure but will usually also require multi-meter for checking various input and out put signals. I usually find this type of system more difficult to trouble shoot since there are more components to work your way through.
I know this all sound intimidating but with some mechanical knowledge and skill most shade tree mechanics can work there way through them.
at 300 hrs is this still under warranty?
Not sure of your mechanical and or electrical skills but a good service manual should show the diagnostic steps or procedures for trouble shooting the HST drive - control. (I have no clue how good or bad MF manuals are) There are two or three main styles of control. Smaller tractors typically direct mechanical control. Very simple to trouble shoot since linkage directly moves the swash plate for directional control. Usually seen on SCUT and CUT.
Another control type: hydro-mechanical where mechanical linkage from treadle pedal operates a control valve assembly that directs pilot pressure to the control piston for the swash plate. Pilot pressure comes from charge circuit. On these there are typically test ports where you take pressure readings to diagnose what is going on. Usually fairly straight forward diagnostic procedure.
Other control type: electro-hydraulic where a variable amperage is applied to a proportional coil on the HST control module for directional control. These have some form of variable signal from the treadle peddle that is input to some form of electronic controller which then outputs the milliamp signal to the coil. On these there could be test ports for monitoring control pressure but will usually also require multi-meter for checking various input and out put signals. I usually find this type of system more difficult to trouble shoot since there are more components to work your way through.
I know this all sound intimidating but with some mechanical knowledge and skill most shade tree mechanics can work there way through them.