every valve is variable it is just like the newer series 2 dozers and T-series. ok heres the technical definition these switches are called Potentiometers they are completely variable and that signal goes to the solenid which meters the oil to the actuator>>>
Every valve is not variable, as there are some implement controls that are ON/OFF. There are no potentiometers whatsoever on the joystick controls. The variable analog signals in the joystick are created using hall effect signals. As a magnet gets closer to an applied current field in the sensor, a greater voltage drop is created. This voltage drop is then electronically converted to a digital signal and sent to the respective controller. If the valve is variable, then the current is sent to the solenoid as a Pulse-Width Modulated signal (PWM). The greater the percentage of ON time of the signal, the farther the travel of the valve spool.
There are some on/off signals from the joystick to the controller. These are on/off signals for throttle resume/decelerate, upshift/downshift, diff lock, and forward-neutral-reverse. Even though these are on/off signals, there is still some tricky logic in regards to the Controllers. The controller will always look for a difference in two states. This requires three wire switches instead of the standard two wire configuration.
These things are a blast...