Automatic shift control system for a powertrain and method

A method for predicting and managing a change in torque in a machine powertrain that includes a prime mover driving ground engaging members via a transmission having a selectively variable power transmission ratio that is selectively shifted in response to commands from a controller operably associated with the transmission, the method comprising:

• monitoring at least one of a position and an orientation of a work implement of a machine with the controller;
• monitoring a ground speed of the machine with the controller;
• determining in the controller whether the at least one of the position and orientation of the work implement is within a respective predetermined range;
• determining in the controller whether the ground speed is below a threshold value;
• and
• when the at least one of the position and orientation of the work implement is determined to be within the respective predetermined range, and the ground speed is below the threshold value,
• issuing a controller command causing the transmission to change its operating condition;
• wherein the controller command causes the transmission to provide a holding torque when the ground speed reduces to zero and the position and orientation of the work implement indicates that the position of the implement is low, which is indicative of a pile dig position;
• and
• wherein the controller command causes the transmission to downshift when the position and orientation of the work implement indicates that the position of the implement is high, which is indicative of a load dump position.

An automatic shift control system for a powertrain of a machine, the machine having an implement being liftable at a height and tiltable at an orientation, the powertrain including a transmission arranged to interconnect a prime mover of the machine with ground engaging members of the machine at a selectively variable ratio such that the machine can travel along a travel surface at a ground speed, the automatic shift control system further comprising:

• a control device associated with the transmission and responsive to selectively vary the selectively variable ratio in response to a shift signal;
• a lift sensor associated with the implement, the lift sensor configured to monitor a parameter indicative of a position of the implement with respect to the travel surface and provide a lift signal indicative of the position;
• a ground speed sensor configured to monitor the ground speed of the machine and provide a ground speed signal indicative of the ground speed;
• a controller associated with the control device, the lift sensor, and the ground speed sensor, the controller disposed to:
• monitor the lift signal and the ground speed signal;
• compare the lift signal to a predetermined position range;
• compare the ground speed signal to a predetermined ground speed range;
• and
• when the ground speed signal is within the predetermined ground speed range and the lift signal is within the predetermined position range, provide a shift signal to the control device, thus causing the selectively variable ratio of the transmission to change;
• wherein the shift signal causes the transmission to provide a holding torque when the ground speed signal reduces to zero and the lift signal indicates that the position of the implement is low, which is indicative of a pile dig position;
• and
• wherein the shift signal causes the transmission to downshift when the lift signal indicates that the position of the implement is high, which is indicative of a load dump position.