Dynamic braking on an all wheel drive machine

A method for dynamically braking an all wheel drive machine having a transmission shiftable with a shift lever, a braking system for braking a first set of wheels, and a pump for hydraulically driving a second set of wheels using pressurized fluid circulating in forward and reverse drive loops for effecting all wheel drive, comprising the steps of:

• turning on an all wheel drive system;
• depressing an inching pedal;
• sensing brake air pressure to said first set of wheels;
• determining ground speed of said machine;
• determining a pump set point current using ground speed;
• setting actual pump current to 90% of the set point current;
• sensing fluid pressure in the forward and reverse drive loops using said shift lever as a determinant;
• designating fluid pressure in one of said forward and reverse drive loops corresponding to a shift position of the shift lever as the shift lever side drive loop pressure and fluid pressure in the other drive loop in the position opposite of the shift lever the opposite side drive loop pressure;
• determining the greater of said shift lever side drive loop pressure and said opposite side drive loop pressure;
• using the greater of said shift lever side drive loop pressure and opposite side drive loop pressure as initial desired brake pressure;
• and
• setting desired brake pressure for said second set of wheels to 8,000 kPa plus the sensed brake air pressure times a predetermined constant when the initial desired brake pressure is greater than a brake pressure corresponding to a pump current that is 30% of said set point current, less than 30,000 kPa and less than a brake pressure corresponding to a pump current that is 90% of said set point current whereby said second set of wheels are driven at a slower rate of speed than said first set of wheels to brake said machine.