Marine and subsea slip rings
Moog Model 303 downhole
Oil-filled slip rings for high-temperature, high-pressure downhole tools, in miniature-bore, large-bore and 20-channel high-voltage versions.
Key specifications
| Circuits (max) | 20 |
|---|---|
| Current per circuit (max) | 10 A |
| Voltage (max) | 1,000 V |
| Speed (max) | 600 rpm |
| Bore | 9.525–88.9 mm |
| Temperature (max) | 230 °C |
Summarised in our own words from Moog Inc.'s published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1 · Source 2
Notes on this data
Pressure 25 kpsi (1,700 bar). 200 °C standard, up to 230 °C. Type marine used as closest energy category.
Specify Motion is not affiliated with Moog Inc.. Moog and Model 303 downhole are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with a Moog part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These 3 series from our supply network are the closest match on published figures.
Sealed slip rings rated IP64 to IP68 for wet, washdown and marine settings such as ships and harbour equipment.
| Published maximum | Model 303 downhole | Waterproof Slip Ring |
|---|---|---|
| Circuits | 20 | 44 meets or exceeds |
| Current per circuit | 10 A | 85 A meets or exceeds |
| Speed | 600 rpm | 600 rpm meets or exceeds |
| Voltage | 1,000 V | 1,100 V meets or exceeds |
| Bore | 88.9 mm | 127 mm meets or exceeds |
Heavy-duty carbon-brush slip rings for very high current and voltage, with copper-graphite power rings and precious-metal signal rings. Large and heavy by design, but straightforward to maintain.
| Published maximum | Model 303 downhole | BHR Series Frameless Type (Carbon Brush) |
|---|---|---|
| Circuits | 20 | 76 meets or exceeds |
| Current per circuit | 10 A | 500 A meets or exceeds |
| Speed | 600 rpm | 10 rpm |
| Voltage | 1,000 V | 20,000 V meets or exceeds |
| Bore | 88.9 mm | — |
Large through-hole slip rings for heavy outdoor plant, with through holes quoted up to 1000 mm and long service life.
| Published maximum | Model 303 downhole | Large Size Slip Ring |
|---|---|---|
| Circuits | 20 | 35 meets or exceeds |
| Current per circuit | 10 A | 50 A meets or exceeds |
| Speed | 600 rpm | — |
| Voltage | 1,000 V | 500 V |
| Bore | 88.9 mm | 1,000 mm meets or exceeds |
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.
Other marine and subsea slip rings series
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