Planetary gearbox
SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G) gearbox
Low-backlash planetary servo gear units in 17 sizes and three performance classes, with one-, two- and three-stage ratios from 3:1 and acceleration torques up to 6,150 Nm (series maximum).
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Key specifications
| Peak torque (max) | 6,150 Nm |
|---|---|
| Ratio | 3–1,000:1 |
| Backlash (max) | 4 arcmin |
| Sizes | 21, 22, 31, 32, 33, 41, 42, 43, 51, 52, 53, 61, 62, 63, 71, 72, 73 |
| Rated life | 20,000 h (60 %) / 30,000 h (100 %) as listed by class |
| Backlash | 1 arcmin to 3-4 arcmin depending on performance class |
| Ratios | 1-stage 3-10; 2-stage 12-100; 3-stage 64-550 (up to 1000 on request for one class) |
| Outputs | smooth or keyed solid shaft, splined shaft DIN 5480, flange block shaft |
| Lubrication | lifetime oil or grease, H1 food-grade options |
Summarised in our own words from SEW-EURODRIVE GmbH & Co KG's published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
The product page lists acceleration torque ranges 40-2,000, 66-4,200 and 80-6,150 Nm across the P5.G/P6.G/P7.G classes but the text extraction did not map each range to a class unambiguously; 6,150 Nm is the series maximum acceleration torque (stored as torque_Nm_peak_max). Rated/continuous torque, IP and efficiency not published on the page.
Specify Motion is not affiliated with SEW-EURODRIVE GmbH & Co KG. SEW-EURODRIVE and PxG planetary servo gear units (P5.G, P6.G, P7.G) are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G) replacement and alternative options
Use these supply-network options as a starting point for an engineering check. We can also help source the original SEW-EURODRIVE 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 high-precision helical planetary with a one-piece stainless planet cage and very short length; ADS adds a keyed input shaft for belt pulley or coupling drive.
| Published maximum | PxG planetary servo gear units (P5.G, P6.G, P7.G) | AD / ADR / ADS |
|---|---|---|
| Peak torque | 6,150 Nm | — |
| Ratio (max) | 1,000:1 | — |
| Backlash (lower is better) | 4 arcmin | 1 arcmin 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 | PxG planetary servo gear units (P5.G, P6.G, P7.G) | P-II / P-IIR |
|---|---|---|
| Rated torque | — | 459 Nm |
| Peak torque | 6,150 Nm | — |
| Ratio (max) | 1,000:1 | 1,000:1 meets or exceeds |
| Backlash (lower is better) | 4 arcmin | — |
High-precision round-flange planetary with high input speed capability and near-zero backlash, aimed at robotics and CNC.
| Published maximum | PxG planetary servo gear units (P5.G, P6.G, P7.G) | WAE |
|---|---|---|
| Peak torque | 6,150 Nm | — |
| Ratio (max) | 1,000:1 | — |
| Backlash (lower is better) | 4 arcmin | 2 arcmin 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 planetary gearbox is
A planetary gearbox reduces speed and multiplies torque using a central sun gear driven by the motor, several planet gears on a carrier, and an outer ring gear. Load is shared between the planets, so the gearbox is compact, coaxial and torque-dense. A single stage typically gives ratios of about 3:1 to 10:1, and stages are combined for higher ratios. Precision servo planetaries use ground helical or spur gears, preloaded output bearings and a motor adapter flange, with backlash typically a few arcminutes or less.
When engineers choose a planetary gearbox
Choose a planetary gearbox for most servo and stepper axes that need more torque, lower reflected inertia or a better inertia match. It is efficient, typically above 95% per stage, stiff and widely available in standard frames. The trade-offs are backlash, which is low but not zero, and limited single-stage ratio. For zero backlash in a compact joint, a strain-wave gear suits better. For very high shock loads, a cycloidal reducer may be more robust.
How to specify the SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G)
Send these with your enquiry and an engineer can confirm the right PxG planetary servo gear units (P5.G, P6.G, P7.G) variant or an equivalent:
- Ratio and output speed (:1, rpm)
- Nominal and peak output torque (Nm)
- Emergency stop torque (Nm)
- Backlash (arcmin) and torsional stiffness (Nm/arcmin)
- Radial and axial output loads (N)
- Motor flange, shaft diameter and length (mm)
- Duty cycle, mounting orientation and lubrication
Common mistakes to avoid
- Sizing on motor torque times ratio without checking acceleration torque and service factors
- Ignoring the input speed limit at high motor speeds
- Mounting a pulley or pinion that overloads the output bearing
- Forgetting the gearbox efficiency and heat in continuous duty
SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G): frequently asked questions
Can you help replace SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G) 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 SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G)?
Low-backlash planetary servo gear units in 17 sizes and three performance classes, with one-, two- and three-stage ratios from 3:1 and acceleration torques up to 6,150 Nm (series maximum). Published series figures include peak torque 6,150 Nm, ratio 3:1, ratio 1,000:1, backlash 4 arcmin. It is made by SEW-EURODRIVE GmbH & Co KG; Specify Motion can help source it or propose an equivalent.
Who makes the SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G)?
The SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G) is made by SEW-EURODRIVE (SEW-EURODRIVE GmbH & Co KG) and is listed here for engineers comparing options. Specify Motion is not affiliated with SEW-EURODRIVE GmbH & Co KG; brand names are used only to identify the product.
What is the peak torque of the SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G)?
The published series maximum peak torque is 6,150 Nm. Individual models and sizes in the PxG planetary servo gear units (P5.G, P6.G, P7.G) 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 SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G)?
We can assess suitable replacement options. On published figures, APEX Dynamics AD / ADR / ADS 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.
How do I choose a planetary gearbox ratio?
Start from the load speed and motor speed range, then check inertia matching and torque. A ratio that brings the reflected load inertia close to the motor inertia improves dynamics. Then confirm peak output torque during acceleration is within the gearbox rating and that input speed stays under the limit.
What backlash does a precision planetary gearbox have?
Precision servo planetary gearboxes typically have backlash from below one arcminute to several arcminutes, depending on grade and stages. Lower backlash costs more. For most positioning axes, a few arcminutes is fine; for robot joints or optics, strain-wave or zero-backlash designs are used.
Further reading: How to select a planetary gearbox · Harmonic vs planetary vs cycloidal · Gearboxes and harmonic drives
Other planetary gearbox series
Engineer support
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Tell us how you use the SEW-EURODRIVE PxG planetary servo gear units (P5.G, P6.G, P7.G): the load, speed, duty and environment. Our engineers will confirm whether it is still the right part, find it for you, or propose an alternative that fits better.
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