Selecting The Most Correct Type and Kind of Swivel Joint
"Because applications are different" and because fluid power swivels are our business, the focus is on continuous advancement of the swivel product lines. This endless goal is supported by technology, manufacturing, and market know how. The desire is to sustain a broad line of products and a high level of service in providing the "most correct type and kind of swivel for the need." Refer to Safety Information, Selection and use of Hydraulics, Inc. Swivel Joints.
How to Distinguish Types of Swivel Joints
The two types of swivel joints discussed here are distinguished by their load bearing mechanisms. Both types require at least two components, commonly referred to as the stem and the barrel.
The first type swivel (Swivel A), is comprised of a barrel fluid port positioned to rotate on a plane 90º to the stem axis. This swivel includes two load bearing mechanisms classed as journal bearings. The swivel's barrel bore includes two load bearing lands separated by a fluid passage. The stem's outer diameter includes bearing lands, complementing the barrel and with space to allow the stem fluid passage to communicate fluid to the barrel port. The two stem bearing lands further include equal size seals for containing the fluid. By nature of equal seal size, (pressure balanced) the effect of fluid pressure on the stem and barrel creates no load on the bearings. Thus bearing life is solely dependent upon external loading. To achieve maximum bearing life, all angular deflection induced through the piping system should be kept to a minimum.
The second type swivel (Swivel B), is distinguished by opposed barrel and stem fluid ports on a common axis. This in-line port relation depends on a single load bearing mechanism, classed as a combination radial-thrust bearing. The swivel's barrel bore provides an axial ball bearing raceway that is distanced from the barrel's seal gland area. The swivel's stem provided an axial ball raceway and a seal groove to coincide with the barrel bore. In assembly, the balls retain the barrel to the stem while permitting axial rotation between the two components. These features require the bearing to withstand both thrust and stress from angular deflection of piping. With no deflection, bearing life is a function of thrust from fluid pressure.