Electrical Slip Rings

Slip rings are electromechanical devices used whenever there is a need to transfer current to or by rotating parts. They generally feature metallic graphite that brushes against a rotating component. However, there are several types of slip rings, each with unique features depending on its application. Slip rings are common in electrical generators, slip ring motors, alternators (packaging industry, wind turbines, cable reels), air conditioning systems, and more. They are also used in transferring power, signals, and control circuits. A through-hole slip ring is a special type of slip ring used for specific applications, usually those that feature components rotating 360 degrees. Here is a brief overview of through-hole slip rings, including their components, functions, and types.

What Is a Through-Hole Slip Ring?

Also known as a through-bore slip ring, this device features a hollow shaft in the center, offering space for channels and wires. Like the general slip ring, it features a stationary and a rotating part. Through-hole slip rings reduce tangling as their design allows conduction materials to be joined on the outside part of the post containing the dimension plates and metallic rings. The hollow space in the middle of the structure can also be used to connect the rotor to the rotating component. These rings are designed for systems that comprise peripherals passing through or extending from the device. Through bore, slip rings come in diameter sizes ranging from 3mm to 300mm to suit different applications.


Through-Hole Slip Ring Features

Besides its hollow pathway, through-hole slip rings offer several other noteworthy features that distinguish it from other existing models. Some of the unique attributes of these slip rings include:

  • Advanced multi-brush technology that ensures low friction and stronger electric current
  • Metal housing and integrated structure design for better unit protection and easy installation respectively
  • Can carry current from 0 to 20A and support 0 to 300 circuits
  • The standard voltage varies from 0 to 600VAC/VDC

Standard models define circuit number, energy, and present. Although through-hole slip rings are generally designed for devices where 360-degree rotation is required to allow signal transduction, not all can facilitate such requirements, so it is always recommended to review the specifications when ordering your device.

What Is the Function of a Through-Hole Slip Ring?

A through-hole slip ring retains the role of standard slip rings, which is to pass signals from a stationary part to a rotating part of the machine. As such, it has two main parts. The first is a stationary metallic brush or graphite and the second is a rotating ring. The only difference is through hole slip rings have a hollow space at the center of the design. However, this space is what distinguishes through bore slip rings from the rest. The stationary graphite brushes transmit electrical signals to the rotating ring, a process that is replicated in the wide variety of slip rings available in the market. Through-hole slip rings exist in several electromechanical devices including loading and unloading power plants, heavy motors, electric generators, and offshore cranes, among others.

Types of Through-Hole Slip Rings

There aren’t any definitive types of through-hole slip rings. However, a quick look at the existing options identifies differences in size, design, and other vital aspects. Slip-through rings can be divided into categories according to current, capacity, technology, housing, and more. Since the demand for these devices is relatively low, most offers are customized to order. There are some apparent classifications, such as high current through hole slip rings, although these are minor and often considered application-dependent differences. You can find reputable brands that are popular for their unique series of dependable slip ring models. The top offers include:

1. Mouflon MT Series

The brand has been around for over 30 years and their MT series is designed for applications that involve installing through-hole pneumatic and hydraulic rotating shafts. Mouflon is popular for its fiber brush technology and multiple contact points per brush. They provide bore size from 3mm to 800mm and supports both power and signals.

2. Senring

Senring is another reputable brand offering hole slip rings for various applications. Devices from this brand feature 0A to 20A current, a voltage rating of 0 to 600VAC/VDC, and bore sizes between 3mm and 300mm. Senring through bore slip rings offer metallic housing and are ideal for applications that require augmented sturdiness.



DSTI offers two options for those seeking through bore slip rings. The first category is a standard device that can be easily integrated directly into your system with minimal modifications. The second option is a customized slip ring manufactured according to your instructions. It is one of the most reliable manufacturers of custom through-hole slip rings.

What is DSTI

4. Rotarx

Rotarx is another highly regarded manufacturer when it comes to through-hole slip rings. Known for their trademark aluminum housing, Rotarx slip rings offer a current rating of 2A to 10A and a voltage rating of 240 to 690VAC/VDC. The bore size ranges from 30mm to 300mm, which suits most standard device installations.

Finding a Vendor

There are several things to keep in mind when looking for through-hole slip rings. For instance, if you plan to operate outdoors, the slip ring should be waterproof. It is essential to inform the vendor or manufacturer of all your requirements. This is very crucial, especially if you plan to use the slip ring in mining, high heights, and other operations with a higher likelihood of an explosion. Another critical feature is the RPM (rotation per minute). Although most devices require low RPM, some have benefited from higher RPM.


Through-hole slip rings are required for unique applications and there are various specifications for each use. As such, most devices are customized to fit the requirements. It is essential to inform the vendor about all conditions, including the operation environment and the specific application. There are several brands available in the market and most offer decent quality slip rings models. However, it is still important to find reputable models from the top brands.


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