What Are Hydraulic Hose Rotary Joints?

 

Hydraulic hose rotary joint

 

Most hydraulics engineers are well aware that proper hose routing often means accommodating machine motion without overly stressing the hose, or letting it rub and abrade against other hoses or machine components. Otherwise, hose can prematurely fail, resulting in leaks, machine damage, downtime, costly environmental contamination and, potentially, a hazard to nearby personnel.

 

Swivel-type fittings are designed to allow the coupling and hose connection to rotate, which prevents twisting, kinking and excessive bending. That can extend hose life and reduce maintenance needs. It can also make for more efficient system plumbing. Using rotary joints can reduce the length of hose required between connections, eliminate the need for bent tubing to accommodate angled connections, and often can be connected directly to the hose line without adapters. Because swivel joints move, they can compensate for hose length changes when the system pressurizes and absorb hydraulic surges and shocks in a line.

 

Thus, many applications can benefit from the use of hydraulic hose rotary joints. These components permit an extensive range of articulation and movement in equipment operation and eliminate torque and twisting in hydraulic hoses. They can also simplify hose installation and maintenance.

 

Components

They consist of two major components, a stem and housing that can rotate relative to one another, as well as internal seals and bearings. Depending on the design, rotation can be unrestricted or somewhat less than 360°. Some rely on ball bearings to control movement, others have so-called ball-less designs with plain thrust bearings.

 

Types

Two basic types are in-line, where the opposing stem and housing fluid ports lie on a common axis; and 90° swivels, where the housing's fluid port is positioned to rotate on a plane 90° to the stem axis.

 

Hydraulic hose rotary joint

 

Applications

They are built to handle high pressures - often in excess of 5,000 psi - offer leak-free performance, resist hydraulic shock and side loads, and won't pull apart in operation. Over time the seals, back-up rings or bearings can eventually wear out, but many designs permit simple repair with seal replacement kits.

 

The swivel or hose should be mounted to the machine structure to ensure proper alignment and freedom of movement. While rotary joints are typically designed to allow free rotation with minimal friction, engineers should be aware that the weight of the attached hose, tubing or fittings - as well as the weight of the contained hydraulic fluid - may be substantial enough to place excessive side loads or bending moments on the swivel. The connection must be specified to handle such loads, or the seals may prematurely wear and leak. Side loading also causes excessive wear on the bearing surfaces and inhibits smooth swivel joint operation.

 

Hydraulic swivels are used in a wide range of rotary applications. Typical examples include grapples, forestry attachments, lift cranes and utility boom trucks, railroad maintenance equipment, demolition shears, and mobile excavators. And in this IoT era, special hydraulic rotary joints can be combined with electrical slip rings to transfer power or data signals. In addition to simple hydraulic swivels, a number of companies make rotary unions and rotating manifolds that transmit fluid from a single housing to multiple lines.

 

Design parameters

As with any other hydraulic component, engineers should consider a number of important design parameters. Swivel housings are available in steel and stainless steel, brass, aluminum and other common materials. Fluid compatibility with the specified materials is, of course, a must, and typical seal options include nitrile, ethylene propylene, neoprene and fluoroelastomer, to name a few.

 

Hydraulic hose rotary joint

 

Other considerations include pressure rating, internal flow characteristics and pressure losses, permissible rotational speed and torque requirements, SAE or ISO fluid ports options, and the ability to handle a range of ambient and fluid temperature ratings.

Many designs have an external exclusion seal to prevent ingression of contaminants, but it's always recommended to protect the swivel from dirt and abrasives whenever possible. For operation in harsh or corrosive conditions, a protective cover or elastomeric bellows are possible options.

 

And almost always, price is an important consideration. The cost of a rotary joint can be more than offset by cost-reduction benefits such as greater system design flexibility, improved system routing with less hose, simpler and quicker installation, fewer adapters and tube fittings, and longer service life.

 

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How Does a Swivel Joint Work?

 

 

Swivel Joints come in various shapes and sizes based upon the application and the environment where it goes through. While style consideration needs to be provided to outside elements, all the swivel joints have 2 primary components: a shaft as well as real estate.

The idea behind a swivel allows the shaft to rotate while the real estate remains fixed-ready. The shaft has actually pierced holes of varying size and also depth beginning with its leading surface area. Variable opening midsts, as well as markings, define the circulation path of fluid within the swivel. Via inner design, the fluid is performed the shaft right into and also out of the swivel joint.

The real estate system includes machined flow as well as grooves to assist in liquid transfer within the swivel and also protect against cross leakages. Phoned number markings are found on the real estate outer diameter surface area and also the same can be discovered on the leading surface area of the shaft.

These numbers specify where an individual would anticipate the fluid to move in/out in between shafts as well as real estate via the machined inner passages. A collection of very carefully selected inner elements are fitted between the shaft as well as real estate at specified locations. These include seals, breaks rings, O rings, wearings, tiny bearings in specific applications.

The choice of interior parts is of vital importance while designing a swivel joint as severe interest needs to be given to the tolerances as well as the inner layout of the real estate grooves. Failing to comply with the advised layout and also machining requirements leads to leaking elements.

The flow of power, as well as signals, are sometimes required for particular applications and industries. Slide rings can be incorporated with the swivel joint via passing electrical cable televisions within the hollow inner size of the shaft.

 

Exactly how to Select a Swivel Joint?

 

In contrast to various other rotary parts in the exact same industries, a swivel joint mostly endures interior loads while functional. This is a direct outcome of pressurized fluid flowing within its interior components. To pick an appropriate swivel joint, multiple influencing factors should be thought about.

The most influencing element on a swivel joint is the inner securing option between the shaft and also housing. Really precise tolerances have to be preserved during the machining phase to create the required grooves for seals as well as inner elements to be fit.

Seals, o-rings, use rings, and bearings are inserted within these internal grooves and have to be able to endure the pressures caused by the fluid Swivel joints are rated by the manufacturer regarding their recommended operating pressures, temperatures, and speeds.

These values are directly associated with the interior elements requirements, geometric machining tolerances, and type of liquid used the substantial layout as well as area factors to consider the need to be given for a swivel joint and its ports.

Based on application needs, a swivel joint might have up to 9 different ports to provide fluid with various flows. A greater variety of paths result in substantial dimension as well as product boost.

Swivel joints can be customized in dimension as well as port dimensions with respect to application requirements. Space constraints, lots requirements, task cycle, as well as environmental surroundings are all variables that are taken into consideration while choosing an appropriate part

 

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