Hydraulic swivel couplings

Hydraulic swivel couplings are metal components whose function is to connect stationary pipes or hoses to rotating parts of machines thus helping to extend massively hoses service life, reducing the impact of wear generated by torsion, kinking, extreme bending and other high stresses.

Different types of hydraulic swivel

A swivel is composed by two main parts: a stem and a housing; their mutual rotation is the key principle that allows for smooth rotation and movement between stationary and rotating parts, preventing flow restrictions and premature failures.

Few other internal components (o-rings, backup rings and bearing balls or thrust washers) are essential as well for a correct functionality of each swivels, as they ensure sealing and capacity of pressure shock absorption.

On in-line swivels stem and housing ports lay on the same plan, whereas on 90° swivels these ports lay on perpendicular plans. Also, swivels can be characterized by ball bearings or by a ball-less design: that’s a crucial feature for these parts, as it influences the capacity to resist to pressure spikes and to side loads. In particular the ball-less design, first developed by the Canadian manufacturer Taimi Hydraulics, offers outstanding performances of pressure shock absorption and side-load, wear and leak resistance.

Benefits of hydraulic swivel

The main benefit ensured by hydraulic swivels is a drastic reduction of unexpected machinery downtime caused by hose breaks and leaks; using swivels along hydraulic lines results also in a shorter overall length of the hose (longer hoses can withstand a little bit better the negative impacts of torsion) and in a simpler and quicker hose installation. Last but not the least, swivels prevent the loosening of hose fittings.

Applications of hydraulic swivel

Hydraulic swivels can be used on a lot of different applications. For instance, hoses that route pressurized hydraulic oil between the crane arm and the head of forestry harvesters are subjected to a relevant torsional movement; the installation of swivel fittings give hydraulic hoses the freedom of movement to prevent the torsional stresses that would otherwise twist them, reducing their service life. Besides Forestry, however, the list of industries where hydraulic swivels are frequently used is quite long and includes Marine and Offshore, Robotics, Cranes, Underground and Open Pit mining, Construction and Demolition machines, Agriculture machinery, Railway , Material handling (straddle carriers), Concentrated solar energy, Hose reels and Drilling.

How to choose a hydraulic swivel

When looking for a hydraulic swivel to install on a specific application, it’s important to double check whether the flow capacity and pressure ratings of the selected item match the application specs. Also, the frequency and the maximum speed of rotation of the moving part is a parameter that must be considered carefully before choosing the swivel, as some types are particularly suitable for continuous rotation, whereas others suit better back-and-forth rotations. Stainless steel or Carbon steel with superior plating treatments could be a necessary option for saline environments, while FKM or other special compounds can be a “must have” for applications where fluid reaches temperatures up to 200°C (400 °F).