Shift control and method

A method for operating a machine having an engine connected to a multi-gear power-shift transmission, the engine operating at a current engine speed and providing a current torque, the method comprising:

• determining a current value for an efficiency parameter of the machine that is at least partially based on engine speed while travelling at a current ground speed and expending a current work under a current gear setting;
• estimating a first alternative value for the efficiency parameter of the machine travelling at substantially the current ground speed and expending at least the current work under a first alternative gear setting;
• estimating a second alternative value for the efficiency parameter of the machine travelling at substantially the current ground speed and expending at least the current work under a second alternative gear setting;
• comparing the current value, the first alternative value and the second alternative value to one another;
• selecting as between the current, first and second values an optimum value;
• maintaining the current gear setting when the current value is selected as the optimum value;
• providing an indication that a gear shift from the current gear setting to the first or second gear setting is desired when, respectively, the first or second alternative value is selected as the optimum value.

A power train including an engine connected to a multi-gear power-shift transmission, the transmission adapted to operate a drive system at a desired ground speed and power output, the power train further comprising an electronic controller configured to:

• determine a current value for an efficiency parameter while the power train is in a condition adapted for causing the drive system to cause travel of a machine at a current ground speed and expend a current work under a current gear setting of the transmission;
• estimate a first alternative value for the efficiency parameter of the power train under a first alternative gear setting of the transmission;
• estimate a second alternative value for the efficiency parameter of the power train under a second alternative gear setting of the transmission;
• compare the current value, the first alternative value and the second alternative value to one another;
• select as between the current, first and second values an optimum value;
• maintain the current gear setting when the current value is selected as the optimum value;
• and
• provide an indication that a gear shift from the current gear setting to the first or second gear setting is desired when, respectively, the first or second alternative value is selected as the optimum value while still adapted to maintain the current ground speed and expend at least the current work.