Quick reverse mechanism for pneumatic boring tool

A method of using an impact-operated, ground-penetrating tool for a boring operation, the tool comprising an interior striker chamber and a valve chamber, the valve chamber being configured to have a front valve chamber and a rear valve chamber, and wherein, the method comprises:

• operating the tool in a forward operating mode by substantially simultaneously pressurizing the rear valve chamber and the interior striker chamber with fluid;
• maintaining the tool in the forward operating mode solely by pressurization of the rear valve chamber;
• and
• operating the tool in a reverse operating mode by substantially simultaneously pressurizing the interior striker chamber and depressurizing the rear valve chamber.

An impact-operated, ground-penetrating tool for use with a primary supply of pressurized fluid and a secondary supply of pressurized fluid, the tool comprising:

• a housing having a front end, a rear portion, and an interior operating chamber with a forward striker surface and a rearward striker surface, wherein the rear portion of the housing includes a primary inlet adapted to receive the primary supply of pressurized fluid and a secondary inlet adapted to receive the secondary supply of pressurized fluid;
• a striker slidably and sealingly supported inside the operating chamber for reciprocal movement therein between the forward striker surface and the rearward striker surface, the striker having a forward impact surface adapted to impact the forward striker surface whereby the tool is operable in the forward mode, a rear impact surface adapted to impact the rearward striker surface whereby the tool is operable in the rearward mode, wherein the striker further comprises a rear end and an interior striker chamber opening at the rear end and ending a distance from the rear end;
• a valve chamber in the rear portion of the housing configured to have a first end, a second end, and comprising a front valve chamber toward the first end and a rear valve chamber toward the second end, the rear valve chamber being in fluid communication with secondary inlet;
• a control sleeve having a front portion terminating in an open front end defining a primary fluid surface, a rear portion terminating in an open rear end defining a secondary fluid surface, and a sleeve passage therethrough. continuous with the front end and the rear end thereof, wherein the rear portion of the control sleeve is sealingly and slidably supported inside the valve chamber such that the rear portion of the control sleeve engages an inner wall of the valve chamber and divides the valve chamber into the front valve chamber and the rear valve chamber, for movement therein in response to pressure, in the rear valve chamber from the secondary supply of pressurized fluid, the control sleeve being movable between a forward position in which the rear portion of the control sleeve approaches the first end of the valve chamber and a rearward position in which the rear portion of the control sleeve approaches the second end of the valve chamber, and wherein the sleeve passage is in constant fluid communication with the primary inlet;
• wherein the rear portion of the striker is slidingly and sealingly supported on the:
• front portion of the control sleeve so that the interior striker chamber is in fluid communication with the sleeve passage whereby the striker is movable in response to pressure from the primary supply of pressurized fluid;
• wherein the rear portion of the striker comprises a, fluid port to provide fluid communication between the interior striker chamber and the interior operating chamber of the housing, the port being positioned so that when the control sleeve is in forward position the striker operates in the forward mode and so that when the control sleeve is in the rearward position the striker operates in the rearward mode;
• wherein the primary fluid surface of the control sleeve is adapted to receive pressure from the primary supply of pressurized fluid in the striker chamber to move the control sleeve toward the rearward position;
• wherein the secondary fluid surface of the control sleeve is adapted to receive pressure from the secondary supply of pressurized fluid in the valve chamber to move the control sleeve toward the forward position;
• and
• wherein a cross-sectional area of the secondary fluid surface taken perpendicular to the longitudinal axis of the control sleeve is greater than a cross-sectional area of the primary fluid surface taken perpendicular to the longitudinal axis of the control sleeve so that pressure from the secondary fluid acting on the secondary fluid surface is sufficient to overcome the pressure of the primary fluid on the primary fluid surface and maintain the control sleeve in the forward position.

An impact-operated, ground-penetrating drilling assembly comprising:

• a boring tool;
• a fluid supply system adapted to supply pressurized fluid to power operation of the boring tool;
• and
• wherein the boring tool comprises:
• a housing having a front end, a rear end, and body defining an interior operating chamber with an inner surface, an exhaust conduit providing communication between the operating chamber and the outside of the tool, a forward striker surface, and a rearward striker surface;
• a striker reciprocally supported within the operating chamber of the housing between the forward and-rearward striker surfaces, the striker having a forward end, a rear portion terminating in a rear end, and a striker body defining an interior striker chamber, wherein the rear portion of the striker sealingly engages the inner surface of the operating chamber to divide the operating chamber into a forward operating chamber and a rearward operating chamber, the rearward operating chamber continuous with the exhaust conduit, wherein the striker body has at least one striker port to provide fluid communication between the forward operating chamber and the interior striker chamber;
• a manifold near the rear end of the housing and comprising a primary conduit and a secondary conduit;
• a primary fluid inlet tube extending from the primary conduit of the manifold;
• a valve chamber configured to have a front valve chamber and a rear valve chamber, the rear valve chamber being in fluid communication with the secondary conduit in the manifold;
• and
• a means for controlling operation of the tool between a forward operating mode and a reverse operating mode.