# US 2014/0196449 A1 · Hydraulic Drive Circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196449 A1 - Document ID: US20140196449A1 - Status: Published application - Kind: A1 - Application number: 13/739,358 - Filed: 2013-01-11 - Published: 2014-07-17 - Earliest claimed: 2013-01-11 - Inventors: Gerry Petty - Web page: https://patentgrep.com/patent/US20140196449A1 ## CPC - F16H 61/444: by changing the number of pump or motor units in operation - F16H 61/421: Motor capacity control by electro-hydraulic control means, e.g. using solenoid valves - B60Y 2200/413: Compactors - F16H 2059/663: {Road slope} - F16H: GEARING - B60Y: INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY ## Abstract A hydraulic drive circuit using a variable displacement bi-directional pump with two (2) two speed motors enabling drive torque variation as required compensating for a changing load distribution on a machine encountering varying weight distributions at the two drives resulting from operating on slopes. ## Claims ### Claim 1 In a hydraulically driven vehicle, a hydraulic drive circuit comprising: at least one bi-directional hydraulic pump in communication with a first hydraulic motor and a second hydraulic motor, wherein said first hydraulic motor drives a first drive, and wherein said second hydraulic motor drives a second drive, wherein each of said first and second hydraulic motors having a first displacement and a second displacement, and wherein said first displacement is lower than said second displacement, wherein said first hydraulic motor is set at said first displacement and said second hydraulic motor is set at said second displacement in order to overcome the shifting of a vehicle's weight distribution while operating on a slope in forward travel, and wherein said first hydraulic motor is set at said second displacement and said second hydraulic motor is set at said first displacement in order to overcome the shifting of the vehicle's weight distribution while operating on the slope in reverse travel, and displacement adjusting means for setting the displacement of said first and second hydraulic motors. ### Claim 2 (depends on 1) The hydraulic drive circuit as recited in claim 1, wherein said first and second hydraulic motors are two (2) speed hydraulic motors. ### Claim 3 (depends on 2) The hydraulic drive circuit as recited in claim 2, wherein each of said two (2) speed hydraulic motors are preset with said first and second displacements. ### Claim 4 (depends on 3) The hydraulic drive circuit as recited in claim 3, wherein said first displacement is set at 25 cc per rev and said second displacement is set at 75 cc per rev. ### Claim 5 (depends on 1) The hydraulic drive circuit as recited in claim 1, wherein said first hydraulic motor is in parallel hydraulic communication with said second hydraulic motor. ### Claim 6 (depends on 1) The hydraulic drive circuit as recited in claim 1, wherein said first drive is a drum. ### Claim 7 (depends on 1) The hydraulic drive circuit as recited in claim 1, wherein said second drive is an axle with wheels. ### Claim 8 (depends on 1) The hydraulic drive circuit as recited in claim 1, wherein said first and second hydraulic motors are variable displacement motors. ### Claim 9 (depends on 8) The hydraulic drive circuit as recited in claim 8, further including a controller that is electrically disposed between a switch and said first and second hydraulic motors. ### Claim 10 (depends on 9) The hydraulic drive circuit as recited in claim 9, wherein said controller receives sensing signals and controls the displacement of said first and second hydraulic motors. ### Claim 11 (depends on 10) The hydraulic drive circuit as recited in claim 10, wherein a first sensor produces a first signal in response to the rotational speed of said first drive, and a second sensor produces a second signal in response to the rotational speed of said second drive. ### Claim 12 (depends on 11) The hydraulic drive circuit as recited in claim 11, wherein said controller includes means responsive to said first and second signals applied to the displacement adjusting means. ### Claim 13 A hydraulic drive circuit comprising: separate drive means for applying torque to first and second drives of a vehicle, a first hydraulic motor for powering the first drive means, a second hydraulic motor for powering the second drive means, wherein each of said first and second hydraulic motors having a first displacement and a second displacement such that wherein said first displacement is lower than said second displacement, a bi-directional hydraulic pump in communication with said first and second hydraulic motors, a controller that is electrically disposed between a switch and said first and second hydraulic motors, wherein said controller receives first and second sensing signals to control the displacement of said first and second hydraulic motors, wherein a first sensor produces said first sensing signal in response to the rotational speed of said first drive, and a second sensor produces said second sensing signal in response to the rotational speed of said second drive. ### Claim 14 (depends on 13) The hydraulic drive circuit as recited in claim 13, wherein said first and second hydraulic motors are two (2) speed hydraulic motors. ### Claim 15 (depends on 14) The hydraulic drive circuit as recited in claim 14, wherein each of said two (2) speed hydraulic motors are preset with said first and second displacement. ### Claim 16 (depends on 15) The hydraulic drive circuit as recited in claim 15, wherein said first displacement is set at 25 cc per rev and said second displacement is set at 75 cc per rev. ### Claim 17 (depends on 13) Thy hydraulic drive circuit as recited in claim 13, wherein said first and second hydraulic motors are variable displacement motors. ### Claim 18 (depends on 13) The hydraulic drive circuit as recited in claim 13, wherein said first hydraulic motor is set at said first displacement and said second hydraulic motor is set at said second displacement while operating the vehicle on a slope in forward travel, and, wherein said first hydraulic motor is set at said second displacement and said second hydraulic motor is set at said first displacement while operating the vehicle on the slope in reverse travel.