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

Claim 10:
11. A hydraulically powered implement for use in connection with a tractor that has a hydraulic pump that supplies pressurized hydraulic fluid to the implement, the implement comprising:
a variable displacement hydraulic motor that has a desired operating speed, a maximum displacement volume and a minimum displacement volume;
a rotating drum driven by the hydraulic motor;
a speed sensor configured to measure the rotational speed of the rotating drum and output a speed signal representative of the measured speed;
a shift module that adjusts the displacement of the hydraulic motor in response to a shift command signal voltage, wherein increasing the shift command signal voltage decreases the displacement of the hydraulic motor and decreasing the shift command signal voltage increases the displacement of the hydraulic motor; and
a controller, wherein the controller includes a computer implemented shift control profile that determines the shift command signal voltage which is sent to the shift module in response to the speed signal output by the speed sensor indicating the measured speed is less than the desired operating speed and the rotational speed of the drum is decreasing, wherein the shift command signal voltage is adjusted to a shift command signal voltage that is larger than a linearly proportional equivalent voltage, where the linearly proportional equivalent voltage is the shift command signal voltage that produces a displacement volume between the maximum displacement volume and the minimum displacement volume that linearly corresponds to a ratio of the measured speed to the desired operating speed.