Rotating unions for hydraulics, pneumatics & fluids
Customised rotating unions for the highest demands
Specification Media Feedthrough
- Number of pneumatic/liquid feedthroughs: 1 – 24
- Connection sizes: M5, 1/8″, ¼”, 3/8″, ½”, 5/8″, 1″, 1¼”
- Connections straight or angled
- Pressure: up to 1300bar, 130MPa; 20000 psi, vacuum 0.01torr, 30HG
- Media: air, vacuum, hydraulic oil, water, hydrogen, nitrogen, steam, cooling water, hot water, acids, bases
- Rotation speed: 0-300 rpm
- Housing material: aluminium, stainless steel
- Protection class: IP51 (higher on request)
- Operating temperature: -30°C … +80°C
Rotating unions for hydraulics, pneumatics & fluids
Unlike electrical slip rings for power, signal and data transmission, classic rotary unions do not have the task of transmitting signals and current between stationary and rotating components. Instead, they enable the sealed transition of a fluid, or gases and compressed air (pneumatic and hydraulic energy), between stationary supply lines and/or rotating components (against each other), such as rollers, spindles or motors. They are therefore not electrical rotating unions, but rotating unions for liquids, gases and pressure. For example, they can carry water, hydraulic fluid, cleaning agents, grease, emulsion, bases, acids, lubricants, coolants and oil, but they can also withstand gas pressure, air pressure, vacuum and hydraulic pressure. Or carry hot steam, for example in the paper industry, where rotating unions with siphons are used. Hot steam is introduced, condenses and is “pressed out” again via a siphon to heat the large dryer rollers. Simple (single-flow) rotating unions are even used in private households, e.g. in swivel taps or in the lawn sprinkler. Multi-flow rotating unions are necessary when different media have to be fed to a component, but also back again.
Application areas for Rotary Joints
Rotating unions are needed in almost all industrial sectors, from the food industry to onshore and offshore wind turbines and construction vehicles such as excavators. Therefore, they have to meet a wide variety of requirements. Depending on what is to be carried out, rotating unions have to fulfil different criteria, from the seal, to the IP protection class, to the material, vibration, acceleration or operating temperature. A classic rotating union for fluids is therefore not automatically also suitable for media routing in the context of hydraulics and pneumatics, since the latter must withstand much more hydraulic or pneumatic pressure (bar), for example. This does not apply to our combined electric pneumatic-liquid rotary joints. They combine the media feed-through for fluids and the signal and power transmission, which are normally handled by separate slip rings, and can also be used as a pneumatic and hydraulic rotating union that can withstand high pressure.
These are just a few of the many criteria that must be met in order to perfectly integrate rotating unions into each individual area of requirement. Together with our experts, we will find the optimum solution for every area. Or you can simply configure your individual slip ring online.
The seal makes the difference
The primary goal of our technology and individual advice: high availability, simple installation, low maintenance and yet a long service life. And achieving these goals for pneumatic rotary unions including normal media feed-through, or combined electrical rotary unions, is significantly more demanding than for purely electrical slip rings or simple rotary unions. Not least because of sealing and wear due to friction. The greatest design challenges are the separation of all media-carrying lines and the wear of the seals. The rotation of inner and outer casing creates constant friction. This is not much of a problem with purely electronic slip rings. But where absolute tightness is required, rubbing rubber rings on plastic or aluminium are a limiting factor for the service life of the component. But we at rotarX have already been able to master these and other challenges for a wide range of industrial sectors.
Differences between classic and hybrid, as well as electric rotating unions
As a combined media guide for pneumatics / hydraulics and fluids is often required in modern industrial and agricultural operations, more and more customers are opting for hybrid rotating unions. The media guides are then not exclusive. Hybrid pneumatic rotary unions can therefore pass both fluid and a pressurised gas. This makes very interesting combinations possible. In addition to the transmission of pneumatic or hydraulic energy, gas, compressed air and vacuum, they can also be used to convey auxiliary and operating materials, such as coolants, cleaning agents or lubricants and hydraulic fluid. They can withstand up to 1300 bar at 300 revolutions per minute.
This means that media supplies, which could previously only be carried out at standstill or at low speed, are now also possible at high speed. The degree of automation and the productivity of the entire system are noticeably increased. In addition, they can be used from -30 °C to + 80 °C (other temperature ranges on request). Up to 24 channels for different media are available for the multi-way rotary unions – from water to pneumatics and gases. All combined in one slip ring body.
The application possibilities are thus practically unlimited. However, these powerful rotating unions are particularly popular with construction vehicles. Especially wheeled and tracked excavators with a rotating superstructure and hydraulic propulsion have at least one hydroelectric feedthrough in the undercarriage. This allows the engine and hydraulic unit to be conveniently accommodated in the rotating superstructure and still reliably supply the rotating motors of the undercarriage with hydraulic pressure. Multi-channel rotary unions also allow return oil and leakage oil to flow back into the hydraulic oil reservoir in the superstructure.
Our electric pneumatic liquid rotary unions offer even greater combination possibilities. These not only combine the media feed-through with the transmission of pneumatic and hydraulic energy, but can also transmit data, control signals and power. One conceivable area of application is in wind turbines, for example, primarily for pitch control. The electrical rotary unions can be used here for the hydraulic control for the blade angle adjustment of the rotor blades in order to adapt them to the wind speed. To do this, they must simultaneously transmit the sensor data of the control system or the anenometer, luminous flux and hydraulic pressure and hydraulic fluid, as well as corresponding auxiliary materials if necessary, and return used materials. This is the only way to optimally turn the blades of the rotor into the wind and to realise the power limitation at high wind speeds in order to avoid damage to the drive train. In addition, this approach saves space, as an electrical slip ring thus does not have to be installed as a separate component, but is already integrated in the rotary union.
Your way to an individual Rotary Joint
The basic prerequisite for the optimal solution is a detailed consultation. Together we define the framework conditions, including the determination of the required media and operating data. We need information from you on detailed process sequences, e.g. when which medium is pressurised, temperature influences, space conditions, but also the range of necessary channels, which must be variable depending on the user, for example at permanently installed work tables (with milling machines or other tools). In this case, a central interface for media and current feed-through is required according to a modular design.
Areas of application for rotating unions
In the context of Industry 4.0, automation and digitalisation, these combinations are becoming more and more popular, as in addition to fluids, gases or compressed air, more and more measured values and control signals also need to be transmitted.
An example of this is a so-called milking carousel. Compared to the classic herringbone milking parlour, a rotating milking carousel enables almost completely automated milking of the dairy cattle. However, this requires not only the milk to be conveyed through a classic rotary milking parlour, but also the measured values, data and, of course, electricity necessary for automation and control.
Another application of these particularly powerful slip rings is in wind turbines. Here they are mainly used for hydraulic control of the rotor blade adjustment. They can transmit sensor data or luminous flux simultaneously with a hydraulic pressure that turns the rotor blades optimally into the wind.
Other application examples for hybrid multiway rotary unions:
- Workpiece and tool detection
- Clamping and releasing
- Cooling (e.g. spindle cooling)
- Plant inspection
- Turning and milling (also in combination)
For the special challenge of designing hybrid rotating unions, our many years of experience pay off. Our modular principle and individual advice from our experts based on your process parameters and environmental requirements enable over 50,000 different combination options.
Compared to a pure power or fluid feedthrough, the feedthrough of gas pressure or hydraulic pressure through a rotating union is an enormous challenge. A complex duct system is created between the rotor and the stator for the passage of the media. In addition, a central media line ends in a rotating coupling. The weak point in this design is the sealing. However, by using high-quality sealing rubbers and sophisticated engineering, these lines can withstand up to 1300 bar – and that at 300 revolutions per minute. This is made possible by the combination of different sealing technologies. Whether it is the mechanical seal, the hydrostatic seal or the elastomer or “plastomer seal”. This enables us to react explicitly to the requirements of media, operating and process parameters of our customers. The most suitable sealing technology is used for each media channel. In special cases, all seals can also be combined in one housing if required.
Rotary Joints for machine tools
At corresponding work tables, more than just one medium had to be introduced, executed or carried out in a rotating machine tool part early on. Sophisticated multi-channel hybrid rotary feed-throughs thus enable not only simultaneous turning and milling, but also system control or cleaning of the table, e.g. with compressed air. And all this via just one central interface, on which the individual channel assignment, depending on the needs of the person currently working on the table, has no influence. This allows the company to react flexibly to a change in channel assignment at any time. The rotary feed-through is uniform for all conceivable variants, whether hydraulics, pneumatics, vacuum or a fluid feed-through, e.g. of coolant, is required.
The increased demand for hybrid rotating unions actually arose from machining processes. Initially, the advantages were mainly for machining operations, e.g. higher productivity and the possibility to combine various functions under rotation. For example, the supply of the workpiece spindle with media during turning, or in combined milling and turning operations, where rotary unions supply e.g. workpiece clamps with media.
Based on our discussion, we develop an individual solution for each customer. Starting as a specialist for wind energy, we have built up a wealth of experience in a wide range of industries over the past decades – from the construction sector and the food industry to robotics and medical technology.
Practical slip ring solutions for your application
Product catalogue for all slip rings
Find out about the different slip rings in our current overview. Transmission technology for complex industrial and safety-relevant applications form the core of our product range. All products can be individually adapted to the applications in order to offer you added value. Premium engineering - that is our claim for every single product we manufacture. We would like to convince you of this.
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