Rotary unions and hybrid joints
Moog Model 70 rotary unions and hybrid joint
Low-speed multi-passage fluid rotary union for gases and liquids.
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Key specifications
| Speed (max) | 30 rpm |
|---|---|
| Temperature (max) | 100 °C |
Summarised in our own words from Moog Inc.'s published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1
Notes on this data
Up to 13 channels, 1,000 psi; 100 °C gases / 60 °C liquids.
Specify Motion is not affiliated with Moog Inc.. Moog and Model 70 are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Moog Model 70 replacement and alternative options
Use these supply-network options as a starting point for an engineering check. We can also help source the original Moog part. Published series figures do not establish an exact-model or drop-in replacement: confirm ratings, fit, interfaces and approvals for your application.
Combined units passing hundreds of electrical circuits plus up to 16 gas or liquid channels, with pressures of 10 MPa or more.
| Published maximum | Model 70 | Pneumatic/Hydraulic Integrated Electri… |
|---|---|---|
| Circuits | — | 48 |
| Current per circuit | — | 30 A |
| Speed | 30 rpm | 300 rpm meets or exceeds |
| Bore | — | 85 mm |
A rotary union that passes air, gases or fluids through rotating interfaces, optionally combined with electrical circuits in one unit. Size, ports and channel count are customised to the machine.
| Published maximum | Model 70 | QR Series Pneumatic/Hydraulic Rotary J… |
|---|---|---|
| Circuits | — | 24 |
| Current per circuit | — | 10 A |
| Speed | 30 rpm | 100 rpm meets or exceeds |
| Voltage | — | 240 V |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
Typical applications
What a rotary unions and hybrid joint is
A rotary union, also called a rotary joint or swivel, transfers fluids such as compressed air, vacuum, hydraulic oil, water or coolant from a fixed supply into a rotating shaft or table. A rotating shaft runs inside a stationary housing, and each fluid passage is isolated by seals between grooves, so several media can pass through one unit. Many designs combine with an electrical slip ring into one assembly, providing both fluid and electrical paths through continuous rotation.
When engineers choose a rotary unions and hybrid joint
Choose a rotary union when pneumatic grippers, vacuum cups, hydraulic clamps or cooling circuits sit on a rotating part. The alternative of hoses limits rotation to a few turns. The trade-offs are seal friction, leakage and wear: seal choice sets pressure, speed and media compatibility, and dry running damages some seals. Mixing vacuum and pressure in one unit needs suitable seals. Combining the union with a slip ring saves space but makes the assembly larger and more application-specific.
How to specify the Moog Model 70
Send these with your enquiry and an engineer can confirm the right Model 70 variant or an equivalent:
- Number of passages and the medium in each
- Pressure and vacuum levels (bar)
- Flow rate or port size (l/min, mm or BSP)
- Fluid temperature (°C) and compatibility
- Speed (rpm)
- Permitted leakage and drain or vent provision
- Electrical circuits if combined with a slip ring
Common mistakes to avoid
- Running a union designed for lubricated media on dry air or without flow
- Not providing a leak drain between media and the electrical section of a combined unit
- Applying side load from rigid pipework instead of using flexible hoses and a torque arm
- Ignoring pressure spikes from valve switching when choosing seals
Moog Model 70: frequently asked questions
Can you help replace Moog Model 70 or source the original?
Send the full model code, quantity and required date. Our engineers can check original-part availability and assess suitable alternatives, including Motion Control Products options where appropriate. We confirm compatibility and any changes needed before recommending a replacement.
What is the Moog Model 70?
Low-speed multi-passage fluid rotary union for gases and liquids. Published series figures include speed 30 rpm, temperature 100 °C. It is made by Moog Inc.; Specify Motion can help source it or propose an equivalent.
Who makes the Moog Model 70?
The Moog Model 70 is made by Moog (Moog Inc.) and is listed here for engineers comparing options. Specify Motion is not affiliated with Moog Inc.; brand names are used only to identify the product.
What is the speed of the Moog Model 70?
The published series maximum speed is 30 rpm. Individual models and sizes in the Model 70 range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the Moog Model 70?
We can assess suitable replacement options. On published figures, Motion Control Products Pneumatic/Hydraulic Integrated Electrical Slip Ring and Motion Control Products QR Series Pneumatic/Hydraulic Rotary Joint are options to assess from our supply network. An engineer confirms the fit against your application before recommending anything.
Can one rotary union pass air, vacuum and water at the same time?
Yes, multi-passage rotary unions isolate each medium in its own groove with seals between them. Each passage must be specified with its medium, pressure and flow, because seals that suit air may not suit water or vacuum. Leakage paths between passages and a drain for any seepage should be agreed with the supplier.
How is a rotary union combined with a slip ring?
A common layout puts the rotary union on the axis and the electrical slip ring around or beside it in a single assembly, so both fluids and electrical circuits pass through one rotating connection. The design must keep fluid away from the electrical rings, often with a drain chamber. Specify both parts together so the supplier can manage sealing, length and bearing loads.
Further reading: How to select a rotary union · How to select a slip ring · Slip rings
Other rotary unions and hybrid joints series
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