US Patent 11858171 Mixer drum drive with variable displacement motor

A drum drive system includes a controller configured to selectively control an engine, a variable displacement pump, and a variable displacement motor of a vehicle to provide a target drum speed for a drum of the vehicle. To provide the target drum speed, the controller is configured to: (i) initially operate the variable displacement motor at a maximum motor displacement and operate the variable displacement pump at a pump displacement that provides the target drum speed without needing to actively manipulate an engine speed of the engine; (ii) increase the pump displacement and decrease a motor displacement without needing to actively manipulate the engine speed while still providing the target drum speed; and (iii) increase the engine speed in response to the pump displacement reaching a maximum pump displacement and the motor displacement reaching a minimum motor displacement if necessary to maintain the target drum speed.