Microprocessor controlled neutral circuit for a power transmission

In a work vehicle, such as an agricultural tractor, a control system for selectively placing a transmission in a neutral state, the transmission being of the type including a plurality of intermeshing gears associated with a plurality of clutches, the clutches being engageable and disengageable in predetermined combinations by electrical energization and de-energization of actuator coils to establish predetermined forward and reverse gear ratios between a vehicle engine and a driven axle through the transmission, the control system comprising:

• a coil enabling circuit including a switch having at least two conductive states for selectively completing and interrupting a common electrical current carrying path to the actuator coils;
• and
• a control circuit coupled to the coil enabling circuit, the control circuit controlling the conductive state of the switch to disable the actuator coils without operator intervention during operation of the vehicle.

A control system for a vehicle transmission of the type including an input shaft, an output shaft, a plurality of intermeshing gears, a plurality of clutches associated with the gears and a plurality of electrical coils energizable to selectively engage and disengage the clutches in predetermined combinations to establish gear ratios between the input shaft and the output shaft, the control system comprising:

• a neutral circuit coupled to the coils, the neutral circuit preventing energization of the coils to place the transmission in a neutral condition upon startup of the vehicle;
• and
• a control circuit coupled to the neutral circuit, the control circuit cooperating with the neutral circuit to selectively prevent energization of the coils after startup of the vehicle.