Stepped Load Pull Back Using Rams
AssigneeEarth Tool Company, L.L.C.
InventorKelvin C. Aus
Life of this patent
Estimating the term…
Abstract
A thrust apparatus for a rod string. The apparatus has a stationary frame, a thrust frame with a rod gripper, two hydraulic cylinders and two rams in fluid communication with the hydraulic cylinders. During low-load operations, the hydraulic cylinders act alone, providing the load to the grippers to pull or push the rod string. When higher loads are required, a check valve is activated, allowing fluid from the hydraulic cylinders to activate the rams. The rams provide additional force to the grippers, and may be activated without mechanical or significant hydraulic changes to the apparatus.
Claims22
An apparatus for pulling a rod string comprising:
- a stationary frame;
- a thrust frame comprising a gripper engageable with the rod string;
- a hydraulic cylinder comprising an extendable rod attached at a first end to the thrust frame and at a second end to the stationary frame wherein the hydraulic cylinder provides extension force between the thrust frame and the stationary frame;
- and
- a ram attached at a first end to the thrust frame and not attached to the stationary frame, the ram comprising an extendable ram rod at a second end, wherein when the ram is in a first condition it is in fluid communication with the hydraulic cylinder and when the ram is in the second condition it is not in fluid communication with the hydraulic cylinder;
- wherein the extendable ram rod provides extension force between the thrust frame and the stationary frame when in the first condition.
An apparatus for pulling a rod string comprising:
- a stationary frame;
- a thrust frame having a gripper for gripping and releasing the rod string, wherein the thrust frame is movable relative to the stationary frame;
- a first hydraulic cylinder attached to and extending between the stationary frame and the thrust frame comprising a retraction port, an extension port, and a fluid exit;
- a first hydraulic ram attached to the thrust frame comprising an inlet port;
- a check valve operable in a first and a second condition, wherein the check valve allows fluid communication between the inlet port of the first hydraulic ram and the fluid exit of the first hydraulic cylinder when in the first condition and wherein the check valve does not allow fluid communication between the inlet port of the first hydraulic ram and the fluid exit of the first hydraulic cylinder when in the second condition;
- and
- a pump for providing fluid to the extension port and the retraction port;
- wherein the first hydraulic cylinder retracts when fluid is provided by the pump to the retraction port and extends when fluid is provided by the pump to the extension port;
- and
- wherein the first hydraulic ram extends and contacts the stationary frame when fluid is provided by the pump to the extension port of the hydraulic cylinder and the check valve is in the first condition.
A method for installing a utility line using an apparatus for pulling a rod string comprising a thrust frame comprising a gripper, a stationary frame, a hydraulic cylinder disposed between the stationary frame and the thrust frame, and a ram in fluid communication with the hydraulic cylinder when a check valve is activated, the method comprising:
- placing the rod within the gripper;
- pushing the rod through an existing pipe;
- attaching a pipe burster to a distal end of the rod;
- gripping a proximate end of the rod with the gripper;
- extending the hydraulic cylinder without extending the ram to pull the pipe burster toward the stationary frame;
- releasing the rod with the gripper;
- retracting the hydraulic cylinder;
- gripping the proximate end of the rod with the gripper;
- and
- extending the hydraulic cylinder without extending the ram to pull the pipe burster toward the stationary frame.
Dependencies are inferred from the claim text.