Abstract: A hierarchical control system for a tandem axle assembly for a vehicle is provided. The hierarchical control system includes a vehicle level controller, an actuator, a shift controller, and a sensor. The shift controller is capable of placing the tandem axle assembly in at least a first operating condition and a second operating condition using the actuator. In response to the sensor and an operating condition of at least one of the power source and the transmission of the vehicle, the shift controller adjusts a manner of placing the tandem axle assembly in at least one of the first operating condition and the second operating condition. The hierarchical control system facilitates performing a shifting procedure in an automatic manner or as desired by an operator of the vehicle without excessively increasing a cost and a complexity of the tandem axle assembly.

Abstract: A hierarchical control system for a tandem axle assembly for a vehicle is provided. The hierarchical control system includes a vehicle level controller, an actuator, a shift controller, and a sensor. The shift controller is capable of placing the tandem axle assembly in at least a first operating condition and a second operating condition using the actuator. In response to the sensor and an operating condition of at least one of the power source and the transmission of the vehicle, the shift controller adjusts a manner of placing the tandem axle assembly in at least one of the first operating condition and the second operating condition. The hierarchical control system facilitates performing a shifting procedure in an automatic manner or as desired by an operator of the vehicle without excessively increasing a cost and a complexity of the tandem axle assembly.

Abstract: A method is disclosed for computing clutch engagement characteristics of a friction clutch system in a vehicle powertrain. A dynamic model of the system is used under conditions that cause clutch slipping. Algebraic equations defining a functional relationship between clutch torque and an engagement angle have characteristic parameters that are estimated using a non-linear least squares technique. The non-linear least squares technique repetitively minimizes the difference between a measured clutch output speed and a clutch output speed from the system dynamic model for the same inputs until a small insignificant error is reached. Parameter estimates are used to update each engagement characteristic.

Abstract: An externally controlled fan drive includes a fluid clutch that alters torque delivered to a fan housing to rotate the fan housing at a target fan speed. An adaptive controller measures the actual fan speed and adaptively updates the control logic to compensate for variable physical characteristics of the fan device.

Abstract: A method is disclosed for estimating clutch engagement characteristics of a friction clutch system in a vehicle powertrain. A dynamic model of the system is used under conditions that cause clutch slipping. Algebraic equations defining a functional relationship between clutch torque and an engagement angle have characteristic parameters that are estimated using a non-linear least squares technique. A non-linear least squares technique iteratively minimizes the difference between a measured output clutch disk speed and an output clutch disk speed from the system dynamic model for the same inputs until a small insignificant error is reached. Parameter estimates are used to compile an estimated clutch engagement characteristic.

Abstract: A method is disclosed for estimating clutch engagement characteristics of a friction clutch system in a vehicle powertrain. A dynamic model of the system is used under conditions that cause clutch slipping. Algebraic equations defining a functional relationship between clutch torque and an engagement angle have characteristic parameters that are estimated using a non-linear least squares technique. A non-linear least squares technique iteratively minimizes the difference between a measured output clutch disk speed and an output clutch disk speed from the system dynamic model for the same inputs until a small insignificant error is reached. Parameter estimates are used to compile an estimated clutch engagement characteristic.