Patent ID: 11889790
Assignee: DOUGHERTY FORESTRY MANUFACTURING, LTD. CO.
Field: Other special machines (Mechanical engineering)
Classification: CPC A  F | IPC A  F

Claim 13:
14. A method for controlling a variable displacement hydraulic motor that is configured to drive a rotating mulcher drum suspended on lifting arms of a tractor, wherein the variable displacement hydraulic motor has a desired operating speed, a maximum displacement volume, a minimum displacement volume, and a total displacement volume between the maximum displacement volume and the minimum displacement volume, the method comprising the steps of:
setting the variable displacement hydraulic motor to an initial displacement volume;
activating a hydraulic pump to provide a source of pressurized hydraulic fluid;
applying the pressurized hydraulic fluid to the variable displacement hydraulic motor to cause the variable displacement hydraulic motor and rotating mulcher drum to rotate;
monitoring a rotational speed of the rotating mulcher drum; and
shifting the displacement of the variable displacement motor when the rotational speed of the rotating mulcher drum decelerates from the desired operating speed, wherein the step of shifting the displacement of the variable displacement motor further comprises:
determining a linearly equivalent displacement volume by:
finding a speed ratio by applying a ratio of the rotational speed of the rotating mulcher drum to the desired operating speed; and
applying the speed ratio to the total displacement volume; and

shifting the variable displacement motor to a displacement volume that is smaller than the linearly equivalent displacement volume.