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rotarX Pancake slip rings for power and signal transmission

Extremely flat slip rings with heights from 20mm to 91.9mm

Electrical specifications

  • number of rings: 2-48
  • rated current: 5-20A per ring
  • Max. working voltage: 240/440 VAC/DC
  • Potential strength: ≥500V @50Hz
  • electrical noise: max 10mΩ
  • insulation resistance:
    1000 MΩ @ 500 VDC

Mechanical specifications

  • Inside diameter: 12,7 – 80mm
  • revolution speed: 0-300 rpm
  • contact material: Silver-Silver, Gold-Gold
  • cable length: freely definable, Standard: 300mm (rotor/stator)
  • Protection class: IP51 (higher on request)
  • working temperature: -30°C … +80°C

Pancake slip rings

Pancake slip rings for short shafts or particularly many contacts. Pancake slip rings are the ideal solution to provide short shafts with any number of contacts. These components get their name from their round, flat shape. They look similar to pancakes. Other names for these components are flat slip rings or disc slip rings.

Their main difference to the conventional slip rings is that the transfer points are not linear but vertical to the axis of rotation. This allows pancake slip rings to be made very thin. In the vertical axis, however, they are correspondingly high. This makes them ideal for installation positions where there is only a very short shaft but sufficient space is available in the transverse direction.

Structure of the pancake slip rings

Pancake slip rings consist of two plates facing each other. Contact rings are arranged in a circle on one plate. Each ring is soldered to a cable, which is led out on one side of the slip ring in a strand. The spring contacts are attached to the opposite plate. These are double or even quadruple. This ensures signal transmission at all times. The spring contacts are also soldered to connecting cables, which in turn are led out of the slip ring housing. Incoming and outgoing cables of the same colour are each connected to each other via a slip ring contact. This avoids mix-ups and facilitates installation. The two plates are rotatably connected to each other. They allow revolving rotations of 360° and more. Depending on the design, the pancake slip rings are shielded against different influencing variables and are permanently encapsulated against the ingress of dust and moisture. This makes these components very durable and reliable. Versions without housing are also available on request.

Use of the pancake slip rings

Pancake slip rings are used wherever the installation space is limited in the longitudinal axis but uncritical in the transverse direction. As they have a rather wide structure, they are less suitable for high rotation speeds. Otherwise the centrifugal forces and the vibrations increase so much that the vibrations can damage the disc slip ring.

Most components of this type are limited to a maximum speed of 300 rpm. The most common use of pancake slip rings, however, is in actuation and control technology. They are often installed on multiple switches, which activate other slip ring contacts in different switching states. Since the setting pins of these switches are only very short, but there is usually plenty of space behind the housing, disc slip rings are ideal aids at this point.

Other applications are for example slow running servo motors, which should also rotate backwards. A particularly frequent application of disc slip rings is behind modern multifunction steering wheels. They reliably transmit the key commands for the car radio or the comfort displays to the relevant actuators.

Advantages of pancake slip rings

The biggest advantage of pancake slip rings is their extremely low profile. They are only a few millimetres high and therefore very space-saving along the longitudinal axis. Due to their contact surfaces, which become larger and larger towards the outside, the disc slip rings also have good thermal behaviour. Due to their design, they practically cool themselves. This cooling property is additionally supported by the use of aluminium housings.

Apart from the open design, the pancake slip rings are shielded at least in protection class IP 40, or IP51 or higher if required. Like every component of this type, pancake slip rings are bidirectional. They are therefore uncritical with regard to their installation position. They always conduct current in both directions. If this is not desired, the incoming and outgoing wiring harnesses can easily be fitted with suitable electronic components, for example diodes.

Another major advantage of the pancake slip rings is their expandability. In contrast to hollow shaft or shaft slip rings, the number of contacts on a single component is very limited. However, due to the low installation height, many pancake slip rings can be connected in series. This means that hundreds of contacts can be easily accommodated on a single rotating shaft by using several pancake slip rings. However, the technical parameters, such as the speed of rotation, must always be maintained,

Disadvantages of pancake slip rings

Pancake slip rings build up quickly at right angles to the longitudinal axis. This makes them less suitable in installation situations where there is not enough space available. Their biggest disadvantage is their strong limitation of the rotation speed. Where shaft and hollow shaft slip rings reach well over 1000 rpm, pancake slip rings are limited to a maximum of 300 rpm. This makes them unsuitable for fast rotating shafts, for example in air or pressure screws. If you have a need for high-performance slip rings for these applications, please call us. We will find the right component for you.

Product variety of pancake slip rings

The pancake slip rings are available with a ring number of 2 – 48. Higher ring numbers are not useful, as they would increase the size of the component too much. The larger a pancake slip ring becomes, the more sensitive it is to high speeds. Due to its small construction, however, several pancake slip rings can be arranged one behind the other without any problems. The caseless slip rings are particularly suitable for this purpose. If this option is chosen, an additional protective enclosure with a suitable sleeve is recommended or required. With housing they are available in a thickness of 20 – 91.1 mm.

Without protective housing they have a thickness of 6 mm in all diameters. Their inner diameter (corresponds to the diameter of the permissible shafts) is up to 80 mm. Pancake slip rings operate safely at a speed of 0-300 rpm. By using silver-silver or gold-gold as contact material for rings and brushes, they are very corrosion-resistant. Their temperature range for all versions is -30 °C to + 80 °C.

Repair of slip rings

Pancake slip rings can be dismantled and are therefore theoretically relatively easy to repair. However, since these products are precision components, we would like to advise against making makeshift repair attempts. Apart from occasional cleaning with a suitable acidifier, no major maintenance and repair work should be carried out on the pancake slip rings. We specify a defined lifetime for each pancake slip ring. The low-priced components can be easily exchanged and replaced with a new part. This gives you a defined condition again, which is reliably maintained until the next replacement interval.

Your way to the ideal pancake slip ring

You will find a comprehensive range of all types of slip rings. In addition to pancake slip rings, we also carry any other type of these special components from the electrical engineering sector. If you do not find the right solution for your challenge in our offer, please contact us. Ideally you should send us an e-mail explaining your project and enclose a sketch.

In a joint discussion we will clarify what the ideal slip ring for your application must look like. We would also be pleased to manufacture special designs for you. You can order from 1 to infinite. Trust our many years of experience. We have been supplying the world with slip rings of consistent quality for decades, which you can also rely on.

Example drawings