If you’ve ever worked with rotating machinery—like wind turbines, packaging equipment, or medical scanners—you know the challenge: how do you transmit power and signals from a stationary part to a rotating part without twisting cables? This is where slip rings come into play. Among the many types available, the through bore slip ring stands out for its versatility and unique design.
In this guide, we’ll break down what a through bore slip ring is, how it works, its benefits, and most importantly, how to choose the right one for your application. Don’t worry—we’ll keep it simple, practical, and useful for both engineers and first-time buyers.
What is a Through Bore Slip Ring?
A through bore slip ring (sometimes called a hollow shaft slip ring) is a type of slip ring with a central hole running through its body. This bore allows you to pass shafts, pneumatic or hydraulic lines, or even additional wiring through the middle, making it highly flexible for different designs.
Compared to compact capsule slip rings, which are solid, the through bore version offers more mounting options and is better suited for equipment with rotating shafts or fluid rotary unions.
Key characteristics:
A hollow center for shafts, cables, or hoses.
Can transmit power, signals, or a combination of both.
Designed for industrial machinery and automation systems.
How Does a Through Bore Slip Ring Work?
Like all slip rings, a through bore slip ring enables the transfer of electrical current and data between a stationary part (the stator) and a rotating part (the rotor). Inside the unit:
Brushes and rings maintain constant electrical contact.
The rotation happens smoothly while avoiding tangled wires.
The central hole provides flexibility to integrate with the machine shaft or add extra lines.
Imagine a wind turbine: the main shaft passes through the bore, while the slip ring transmits sensor signals and power between the rotating blades and the stationary control system.
Advantages of Through Bore Slip Rings
Why choose a through bore slip ring over other types? Here are the main benefits:
Flexible Installation – The hollow shaft design makes it easy to mount on existing rotating shafts.
Multi-Utility – Can combine electrical, pneumatic, or hydraulic transmission in one assembly.
High Current Capacity – Larger bores can accommodate slip rings with bigger power circuits.
Long Service Life – Built with durable materials for industrial environments.
Customizable – Bore size, circuit count, current rating, and housing can be tailored to your needs.
Common Applications
Through bore slip rings are widely used in industries where machinery rotates continuously or intermittently. Some examples include:
Wind turbines – transmitting power and signals while the shaft passes through the bore.
Packaging machinery – for power and control signals in high-speed operations.
Medical imaging equipment (CT scanners) – enabling reliable data transfer with a rotating gantry.
Robotics – when pneumatic lines and electrical circuits need to pass together.
Heavy equipment – cranes, radar systems, and cable reels.
How to Choose the Right Through Bore Slip Ring
Now the most important question: how do you pick the right one for your project? Here’s a step-by-step guide.
1. Define the Bore Size
Measure the shaft or the components that need to pass through the slip ring. Bore sizes can range from 12.7 mm (½ inch) to more than 200 mm.
2. Determine Power and Signal Requirements
Power circuits: What current and voltage levels are needed?
Signal circuits: Do you need Ethernet, CAN bus, or other data transmission?
3. Consider Operating Speed
Most through bore slip rings operate at speeds up to 250 rpm, but special designs can handle higher.
4. Check Environmental Conditions
Factors like temperature, dust, moisture, and vibration can affect performance. You may need IP-rated or ruggedized designs.
5. Decide on Housing Material
Aluminum for lightweight use.
Stainless steel for corrosion resistance.
6. Think About Maintenance
Some models are designed for low-maintenance operation, which reduces downtime in industrial environments.
FAQs about Through Bore Slip Rings
Q1: What is the difference between a through bore slip ring and a capsule slip ring?
A capsule slip ring is compact and solid, while a through bore slip ring has a hollow shaft, making it more versatile for industrial machinery.
Q2: Can through bore slip rings handle data signals like Ethernet?
Yes, modern designs support Ethernet, USB, CAN bus, and other communication protocols alongside power circuits.
Q3: Do through bore slip rings require maintenance?
Most are designed for long service life, but depending on the material (copper vs. precious metal brushes), some maintenance may be required.
Q4: What bore sizes are available?
Bore sizes typically range from 12.7 mm to over 200 mm, with custom options available for special projects.
Q5: How do I choose the right slip ring supplier?
Look for experience, customization ability, and proven success in your industry. Request detailed specifications before ordering.
A through bore slip ring is the ideal solution when your application requires both rotation and a hollow shaft for passing cables, shafts, or fluid lines. By considering bore size, current requirements, speed, and environment, you can select the right model to ensure reliable performance.
Whether you’re designing wind turbines, packaging machines, or advanced medical equipment, choosing the right through bore slip ring is critical for efficiency and long-term reliability.
If you’re ready to explore options, JARCH Slip Ring offers customizable solutions to fit your exact needs.