Abstract: A transmission having one or more clutches and brakes wherein only one clutch or brake need be engaged to connect the input to the output is equipped with a two-step actuator valve arrangement in which two valves, arranged in series, must be opened before any clutch or brake is engaged to power the output shaft. A single first-step actuator valve is arranged in series with a plurality of second-step actuator valves. Each of the second-step valves controls a clutch or brake.

Abstract: A transmission having one or more clutches and brakes wherein only one clutch or brake need be engaged to connect the input to the output is equipped with a two-step actuator valve arrangement in which two valves, arranged in series, must be opened before any clutch or brake is engaged to power the output shaft. A single first-step actuator valve is arranged in series with a plurality of second-step actuator valves. Each of the second-step valves controls a clutch or brake.

Abstract: A work vehicle such as an agricultural tractor includes means for the operator to select between manual or automatic engine speed control and to select among multiple automatic modes each having a different amount by which the engine speed is reduced when the load is reduced and the transmission is up-shifted to maintain the vehicle ground speed. This enables the operator to match the degree of engine speed reduction to the particular task at hand for improved performance and productivity. Preferably, the transmission is an infinitely variable transmission whereby the engine speed and the transmission can both be varied infinitely.

Abstract: A method and apparatus for detecting a restricted or bypassed transmission oil filter by providing pressure transducers on both sides of the oil filter whereby the pressure differential will indicate the extent of filter restriction. A first alarm is activated at a first pressure differential to indicate a restricted filter and the need for filter replacement. A second, higher level, alarm is activated to indicate the filter is bypassed and the engine is reduced in speed to allow the pressure and the pressure differential to drop to the point that the filter is no longer bypassed. This enables the vehicle to be operated with limited capabilities to allow the vehicle to be driven to the shop for filter replacement. If the lowered engine speed is insufficient to reduce the pressure differential to stop the bypass, then the engine speed is further reduced to a low idle and the transmission shifted to neutral.

Abstract: The output speed of a hydrostatic unit in a transmission is determined using a pair of variable reluctance sensors, one on a gear driven by the hydrostatic unit output and the other on the carrier of the planetary system. One of the two sensors will always be measuring a relatively high speed from which the hydro output is directly determined or indirectly determined using the current engine speed. Thus the frequency of the speed sensor used to determine the hydrostatic unit output speed is not decreased at slow hydrostatic unit output speeds.

Abstract: A work vehicle such as an agricultural tractor includes means for the operator to select between manual or automatic engine speed control and to select among multiple automatic modes each having a different amount by which the engine speed is reduced when the load is reduced and the transmission is up-shifted to maintain the vehicle ground speed. This enables the operator to match the degree of engine speed reduction to the particular task at hand for improved performance and productivity. Preferably, the transmission is an infinitely variable transmission whereby the engine speed and the transmission can both be varied infinitely.

Abstract: A tractor includes various actuators or functions, such as a powershift transmission, a hitch and hitch control system, a PTO, a plurality of selective control valves, etc., all controlled by one or more control units in response to sensed parameters and operator manipulated control devices, such as switches, knobs and levers. A function management system includes a programmed control unit which has a learn/save mode which is operable while the vehicle is moving. During the learn/save mode the operator performs a sequence of manual manipulations of the operator control devices, and the control unit records and then stores information pertaining to the sequence of operations, together with information pertaining to the distances traveled by the tractor between operations.

Abstract: A tractor includes various actuators or functions, such as a powershift transmission, a hitch and hitch control system, a PTO, a plurality of selective control valves, etc., all controlled by one or more control units in response to sensed parameters and operator manipulated control devices, such as switches, knobs and levers. A function management system includes a programmed control unit which has a learn/save mode which is operable while the vehicle is moving. During the learn/save mode the operator performs a sequence of manual manipulations of the operator control devices, and the control unit records and then stores information pertaining to the sequence of operations, together with information pertaining to the distances traveled by the tractor between operations.

Abstract: A vehicle transmission controller responds of a load signal representing a load on the vehicle engine. The load signal is automatically and repeatedly adjusted as a function of an operational status of the auxiliary vehicle function, and the load signal is automatically adjusted during a shift of the transmission.

Abstract: An electrical circuit applies an oscillatory electrical current to a coil of a solenoid in order to cause the solenoid to move in response to a command signal. The circuit includes a signal divider for generating an upper peak current signal value from the command signal and a lower peak current signal value which is a fixed percentage of the upper peak current signal value. A current sense resistor generates a current sense voltage representing current through the coil. A first comparator compares the current sense voltage to the upper current signal value. A second comparator compares the current sense voltage to the lower current signal value. A set/reset flip-flop latches a current driver on and off. A current driver applies a driving current to the solenoid coil as a function of output signals generated by the first and second comparators so that the coil current will have a lower peak current value which is substantially a fixed percentage of the upper peak current value.