Abstract: A downhole actuator typically for a downhole tool such as a valve, and typically for incorporation in a string of tubulars in an oil or gas well has a central axis with radially movable counterweights on opposite sides of the axis, which move radially outward to change the activation state of the actuator. The counterweights are supported by link arms which control the movement of the counterweights in response to centrifugal force created by rotation of the body, for example, during rotary drilling operations of the string. Radial outward movement of the counterweights typically transmits axial forces between sleeves at the upper and lower ends of the counterweights, so when the counterweights move radially outward, the upper and lower sleeves approach one another, which typically triggers the actuator.

Abstract: A downhole actuator typically for a downhole tool such as a valve, and typically for incorporation in a string of tubulars in an oil or gas well has a central axis with radially movable counterweights on opposite sides of the axis, which move radially outward to change the activation state of the actuator. The counterweights are supported by link arms which control the movement of the counterweights in response to centrifugal force created by rotation of the body, for example, during rotary drilling operations of the string. Radial outward movement of the counterweights typically transmits axial forces between sleeves at the upper and lower ends of the counterweights, so when the counterweights move radially outward, the upper and lower sleeves approach one another, which typically triggers the actuator.

Abstract: A downhole actuator typically for a downhole tool such as a valve, and typically for incorporation in a string of tubulars in an oil or gas well has a central axis with radially movable counterweights on opposite sides of the axis, which move radially outward to change the activation state of the actuator. The counterweights are supported by link arms which control the movement of the counterweights in response to centrifugal force created by rotation of the body, for example, during rotary drilling operations of the string. Radial outward movement of the counterweights typically transmits axial forces between sleeves at the upper and lower ends of the counterweights, so when the counterweights move radially outward, the upper and lower sleeves approach one another, which typically triggers the actuator.

Abstract: A downhole actuator or valve for inclusion in a downhole drill string used in a well includes an obstructing member, such as a piston, moveable between: a first position and a second position; and a retaining member, such as a ball, moveable between: a retaining position which retains the obstructing member in the first position; and, a release position which does not retain the obstructing member in the first position and/or allows or causes the obstructing member to move to the second position. The retaining member is moved in use between the retaining position and release position at least in part by centrifugal forces caused by rotation of the entire drill string within which the downhole actuator/valve is included. Thus, at least some control of the actuation of the downhole actuator/valve may be afforded by rotation thereof.

Abstract: A downhole actuator typically for a downhole tool such as a valve, and typically for incorporation in a string of tubulars in an oil or gas well has a central axis with radially movable counterweights on opposite sides of the axis, which move radially outward to change the activation state of the actuator. The counterweights are supported by link arms which control the movement of the counterweights in response to centrifugal force created by rotation of the body, for example, during rotary drilling operations of the string. Radial outward movement of the counterweights typically transmits axial forces between sleeves at the upper and lower ends of the counterweights, so when the counterweights move radially outward, the upper and lower sleeves approach one another, which typically triggers the actuator.