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

Claim 0:
1. A horizontal directional drilling machine comprising:
a drill string rotational drive unit having an output member configured to connect with and selectively drive rotation of a drill string, the drill string rotational drive unit including a hydraulic motor;
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 including a first rotary ball valve configured to selectively connect the hydraulic motor to one of an inlet side and an outlet side of a drive pump, and
a second fluid flow path including a second rotary ball valve configured to selectively connect the hydraulic motor to the other of the inlet side and the outlet side of the drive pump; 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 first configuration and fluid flows between the drive pump and the hydraulic motor along the first and second fluid flow paths, there is no pressure drop across the first and second rotary ball valves.