Method and apparatus for shifting speeds in a fluid-actuated motor

A method of changing operating characteristics of a downhole tool comprising the steps of:

• pumping a fluid down a drill string through a power section of the downhole tool;
• and
• diverting a portion of the fluid around the power section of the tool using a bypass valve containing a cam mechanism, the step of diverting occurring without expelling fluid outside the drill string,
• wherein the cam mechanism indexes to effect changes in the operating characteristics of the downhole tool.

An apparatus comprising:

• a motor having a power section capable of imparting rotational motion to a drill bit;
• a bypass valve using a cam mechanism for diverting a fluid flow around the power section to change an operating characteristic of the motor, the cam mechanism being adapted to index about an axis of the fluid flow;
• and
• a flow control path for maintaining the diverted fluid flow inside a drill string.

An apparatus for controlling fluid flow through a power section of a tool comprising:

• a valve including a spring-biased cam having an index ring;
• a first flow control path in communication with the valve for conducting a fluid through the power section of the tool;
• and
• a second flow control path in communication with the valve for diverting the fluid around the power section of the tool while maintaining the diverted fluid inside the tool, wherein the valve controls the amount of fluid flow through at least one of the flow control paths.

An apparatus for controlling fluid flow through a power section of a tool comprising:

• a first valve;
• a first flow control path in communication with the valve for conducting a fluid through the power section of the tool;
• a second flow control path in communication with the valve for diverting the fluid around the power section of the tool, wherein the valve controls the amount of fluid flow through at least one of the flow control paths;
• and
• a second valve in communication with the first and second flow control paths wherein the second valve controls the amount of fluid flow through at least one of the flow control paths.

An apparatus for controlling fluid flow through a power section of a tool comprising:

• a first valve;
• a first flow control path in communication with the valve for conducting a fluid through the power section of the tool;
• a second flow control path in communication with the valve for diverting the fluid around the power section of the tool, wherein the valve controls the amount of fluid flow through at least one of the flow control paths;
• and
• a second valve in communication with a third and a fourth flow control path, wherein the third flow control path conducts the fluid through the power section of the tool and the fourth flow control path diverts the fluid around the power section of the tool, and wherein the second valve controls the amount of fluid flow through at least one of the third and fourth flow control paths.