Patent ID: 11946372
Assignee: VERMEER MANUFACTURING COMPANY
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 10:
11. A horizontal directional drilling machine comprising:
a cam-lobe radial piston hydraulic motor having an output member configured to connect with and selectively drive rotation of a drill string;
a hydraulic circuit having a first configuration that puts the hydraulic motor in a drive mode to apply torque to the drill string through the output member, the hydraulic circuit having a second configuration that puts the hydraulic motor in a freewheel mode disabled from applying torque to the drill string, the hydraulic circuit including
a first fluid flow path for selectively connecting the hydraulic motor to one of an inlet side and an outlet side of a drive pump, and
a second fluid flow path for selectively connecting the hydraulic motor to the other of the inlet side and the outlet side of the drive pump, wherein, when the hydraulic circuit is in the freewheel mode, the first and second fluid flow paths are blocked;

a first rotary ball valve positioned along the first fluid flow path and operable to selectively open and close the first fluid flow path;
a second rotary ball valve positioned along the second fluid flow path and operable to selectively open and close the second fluid flow path; and
an actuator with an output coupled with a linkage operable to selectively open the first and second rotary ball valves concurrently and operable to selectively close the first and second rotary ball valves concurrently,
wherein, when the hydraulic circuit is in the drive mode, there is no reduction in cross-sectional area along the first fluid flow path and there is no reduction in cross-sectional area along the second fluid flow path.