Cycloidal gearbox
Sumitomo Drive Technologies Fine Cyclo C-Series cycloidal gearbox
Cycloidal precision reducer with a large 99 mm hollow bore for cables and services, allowable peak torques of 540 to 6,278 Nm, ratios 29:1 to 119:1 and lost motion under 1 arcmin.
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Key specifications
| Bore (max) | 99 mm |
|---|---|
| Peak torque (max) | 6,278 Nm |
| Ratio | 29–119:1 |
| Lost motion | <1 arcmin |
| Emergency stop torque max | 12,577 |
| Torsional stiffness | up to 1,030 Nm/arcmin |
Summarised in our own words from Sumitomo Heavy Industries, Ltd.'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1 · Source 2
Notes on this data
Fine Cyclo is a cycloidal reducer; recorded as type planetary because the allowed gearbox types have no cycloidal option.
Specify Motion is not affiliated with Sumitomo Heavy Industries, Ltd.. Sumitomo Drive Technologies and Fine Cyclo C-Series are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Sumitomo Drive Technologies Fine Cyclo C-Series replacement and alternative options
Use these supply-network options as a starting point for an engineering check. We can also help source the original Sumitomo Drive Technologies part. Published series figures do not establish an exact-model or drop-in replacement: confirm ratings, fit, interfaces and approvals for your application.
Apex Dynamics helical planetary range in inline (AE) and right-angle (AER) forms. AES/AESR are the all-stainless body versions with food-grade grease for washdown and corrosive areas.
| Published maximum | Fine Cyclo C-Series | AE / AER / AES / AESR |
|---|---|---|
| Peak torque | 6,278 Nm | — |
| Ratio (max) | 119:1 | 200:1 meets or exceeds |
Apex Dynamics economy planetary family (PE, PG, PA, PS, PN, PD, PL sub-series) for high-volume automation; standard backlash, inline or right-angle.
| Published maximum | Fine Cyclo C-Series | P-II / P-IIR |
|---|---|---|
| Rated torque | — | 459 Nm |
| Peak torque | 6,278 Nm | — |
| Ratio (max) | 119:1 | 1,000:1 meets or exceeds |
Ultra-flat cup-type strain-wave gear with a very short axial length, light weight and high stiffness for its size.
| Published maximum | Fine Cyclo C-Series | LCD |
|---|---|---|
| Peak torque | 6,278 Nm | — |
| Ratio (max) | 119:1 | 500:1 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.
Typical applications
What a cycloidal gearbox is
A cycloidal gearbox reduces speed with one or more lobed cycloid discs driven by an eccentric input shaft, rolling inside a ring of pins. Each input revolution moves the disc by one lobe, so high ratios are achieved in a compact stage. Many pins share the load, giving high torque capacity, stiffness and shock resistance. Precision robot types, often called RV reducers, add a planetary input stage and support the output with large integrated bearings. Backlash is typically very low.
When engineers choose a cycloidal gearbox
Choose a cycloidal reducer for heavy, stiff, shock-resistant joints such as robot bases, shoulders, positioners, turntables and machine tool axes. It handles high moment loads and impact better than strain-wave gears. The trade-offs are weight, size and cost compared with planetary units, and some ripple at the output. For compact light joints, a strain-wave gear is lighter. For general servo axes, planetary units are cheaper.
How to specify the Sumitomo Drive Technologies Fine Cyclo C-Series
Send these with your enquiry and an engineer can confirm the right Fine Cyclo C-Series variant or an equivalent:
- Ratio (:1)
- Rated and peak output torque (Nm)
- Emergency stop torque (Nm)
- Moment and axial load on output bearing (Nm, N)
- Torsional stiffness (Nm/arcmin)
- Backlash and lost motion (arcmin)
- Input arrangement and motor interface
Common mistakes to avoid
- Ignoring tilting moment from offset payloads on the output bearing
- Not checking emergency stop torque
- Skipping the recommended grease change interval
- Sizing on average torque only
Sumitomo Drive Technologies Fine Cyclo C-Series: frequently asked questions
Can you help replace Sumitomo Drive Technologies Fine Cyclo C-Series 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 Sumitomo Drive Technologies Fine Cyclo C-Series?
Cycloidal precision reducer with a large 99 mm hollow bore for cables and services, allowable peak torques of 540 to 6,278 Nm, ratios 29:1 to 119:1 and lost motion under 1 arcmin. Published series figures include bore 99 mm, peak torque 6,278 Nm, ratio 29:1, ratio 119:1. It is made by Sumitomo Heavy Industries, Ltd.; Specify Motion can help source it or propose an equivalent.
Who makes the Sumitomo Drive Technologies Fine Cyclo C-Series?
The Sumitomo Drive Technologies Fine Cyclo C-Series is made by Sumitomo Drive Technologies (Sumitomo Heavy Industries, Ltd.) and is listed here for engineers comparing options. Specify Motion is not affiliated with Sumitomo Heavy Industries, Ltd.; brand names are used only to identify the product.
What is the bore of the Sumitomo Drive Technologies Fine Cyclo C-Series?
The published series maximum bore is 99 mm. Individual models and sizes in the Fine Cyclo C-Series 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 Sumitomo Drive Technologies Fine Cyclo C-Series?
We can assess suitable replacement options. On published figures, APEX Dynamics AE / AER / AES / AESR and APEX Dynamics P-II / P-IIR are options to assess from our supply network. An engineer confirms the fit against your application before recommending anything.
What is the difference between a cycloidal and a strain-wave gear?
A cycloidal gear uses rigid lobed discs rolling on pins, giving high stiffness and shock resistance. A strain-wave gear uses a flexible spline, giving compact high ratios and near-zero backlash at lower weight. Cycloidal suits heavy base joints; strain-wave suits lighter, compact joints.
What is an RV reducer?
An RV reducer is a precision cycloidal gearbox with a planetary input stage feeding two or more cycloid discs, plus a large integrated output bearing. The design gives high torque, stiffness and moment capacity in a compact package, which is why it is common in industrial robot joints.
Further reading: Harmonic vs planetary vs cycloidal · How to select a gearbox · Gearboxes and harmonic drives
Other cycloidal gearbox series
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