9.1 #Standard_Knuckle_Joint is a #toolstring accessory, used to provide flexibility within the #wireline_toolstring.

It is recommended to place a #knuckleJoint immediately below the #rope_socket when the #ropesocket does not accommodate wireline twist.

An added benefit is that both the upper and lower connections have #fish_necks.

9.2 #HeavyDutyKnuckleJoints are especially important if #tubing is corkscrewed and when #wireline work is to be performed in a #directional_hole.

Where #stem and #jars will not align, or move freely, it may be impossible to operate tools.

However, the #knuckle_joint acts to prevent the #wireline_tools from hanging up.

9.3 The Multi-Roller Wheel Knuckle Joint is designed for use in the deviated wells.

The 360 degrees wheel contact which reduces the friction caused by the contact with tubing wall.