Abstract: A support structure for a rig above a wellhead, such as a snubbing unit, is provided which directs loads from the rig into the ground to minimize stress on the wellhead components. The support structure generally comprises a support plate to be secured onto a wellhead and onto which the rig is secured and at least three ground engaging members distributed around and connected to the support plate, with the ground engaging members accepting the load placed on the support plate. The ground engaging members can be independently vertically adjustable, such as jack stands, for distributing the load between the ground engaging members. The support structure can also be adapted to be movable between a compact shipping position and a deployed operating position.

Abstract: A roller chain and sprocket system utilizes an involute profile on the sprocket teeth to engage rollers in the links of a roller chain. The links, when aligned linearly, bear upon one another when pushed to form a substantially rigid column which has an axis. The system results in substantially 100% of the rotational energy imparted to the sprocket being translated into linear motion of the chain along the column axis.

Abstract: A support structure for a rig above a wellhead, such as a snubbing unit, is provided which directs loads from the rig into the ground to minimize stress on the wellhead components. The support structure generally comprises a support plate to be secured onto a wellhead and onto which the rig is secured and at least three ground engaging members distributed around and connected to the support plate, with the ground engaging members accepting the load placed on the support plate. The ground engaging members can be independently vertically adjustable, such as jack stands, for distributing the load between the ground engaging members. The support structure can also be adapted to be movable between a compact shipping position and a deployed operating position.