Abstract: A method for shifting a powershift transmission of a vehicle in accordance with the load being experienced by the engine as estimated from certain engine operating parameters. A turbocharger associated with an engine operating at a given engine speed generates a turbo boost pressure. The turbo boost pressure is monitored by a sensor and a turbo boost signal is generated therefrom. Similarly, the engine speed is monitored by a sensor and an engine speed signal is generated therefrom. The turbo boost and engine speed signals are used to estimate the engine load based on empirical data stored in the transmission controller's memory, and a percentage load is computed therefrom. The percentage load is then used to generate an appropriate duty cycle and time value for a pulse-width-modulated shift signal which controls the modulation of an on-coming directional clutch into engagement at a desired rate of engagement dependent upon the load being experienced by the vehicle.

Abstract: An electronic transmission control system for a self-propelled off-road vehicle having an internal combustion engine and multiple gear powershift transmission controls the powershift transmission and provides the at least on control signal to the engine for selecting the speed at which the engine is to operate. The system preferably includes a first electronic controller that provides transmission control signals required to command the powershift transmission to shift to and operate in any particular one of its forward gears, and a second electronic controller that provides at least one engine control signal required to command the engine to operate at one of a number of different desired engine speeds and to monitor the actual engine speed.

Abstract: A method for controlling shifting of a powershift transmission of an agricultural vehicle in accordance with a boost pressure developed by a turbocharger of an engine associated with said vehicle. The turbocharger generates a turbo boost pressure which is indicative of the engine torque being produced by the engine at a given time. The turbo boost pressure is monitored by a sensor which generates a boost pressure signal in accordance with the sensed boost pressure. This signal is then modified in accordance with the sensed engine speed of the vehicle to produce a compensated turbo boost signal. The compensated turbo boost signal is compared against predetermined full-load and no-load turbo boost values to determine the percentage value of full-load boost pressure, and thus the load on the engine, at a given time.

Abstract: An electronic transmission control system for a self-propelled off-road vehicle having an internal combustion engine and multiple gear powershift transmission. The control system controls the powershift transmission and provides at least one control signal to the engine for selecting the speed at which the engine is to operate. The system includes a first electronic controller that provides transmission control signals required to command the powershift transmission to shift to and operate in any particular one of its forward gears, and second electronic controller that provides at least one engine control signal required to command the engine to operate at one of a number of different desired engine speeds and to monitor the actual engine speed.

Abstract: An expandable, modular microcomputer system for an off-road vehicle having a controller which is operable to generate a plurality of independent pulse-width modulated control signals and a plurality of independent on/off control signals to a corresponding plurality of metal oxide silicone field effect transistors (MOSFETS). An RS-485 bi-directional serial communications interface enables the system to communicate with at least one other ingredient, external, controller. Thus, the control system can be modularly expanded to handle the needs of increasingly complex powershift transmissions. A watchdog circuit monitors operation of the controller and is supplied with a regulated voltage independent of the regulated voltage used to power the microcomputer. The watchdog can provide a reset signal to the microcomputer when spurious operation of the microcomputer is detected, as well as initiate operation of a back-up voltage supply circuit.