Planetary gearbox
Portescap R22HT planetary gearhead gearbox
All-metal high-torque version of the 22 mm planetary gearhead, ratios 10.9:1 to 850.3:1 in 2 to 4 stages, up to 3.7 Nm continuous and 4.2 Nm static with 62–82% efficiency.
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Select everything you need. A motor, drive and gearbox can be specified together as one axis.
Key specifications
| Outer diameter (max) | 22 mm |
|---|---|
| Rated torque (max) | 3.7 Nm |
| Peak torque (max) | 4.2 Nm |
| Ratio | 10.9–850.3:1 |
| Backlash (max) | 114 arcmin |
| Efficiency | 62–82% by stage count |
| Backlash | average no-load 1.2–1.9° by stage count |
| Bearings | ball bearing |
Summarised in our own words from Regal Rexnord's published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
torque_Nm_peak_max is the static maximum.
Specify Motion is not affiliated with Regal Rexnord. Portescap and R22HT planetary gearhead are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Portescap R22HT planetary gearhead replacement and alternative options
Use these supply-network options as a starting point for an engineering check. We can also help source the original Portescap 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 economy planetary family (PE, PG, PA, PS, PN, PD, PL sub-series) for high-volume automation; standard backlash, inline or right-angle.
| Published maximum | R22HT planetary gearhead | P-II / P-IIR |
|---|---|---|
| Rated torque | 3.7 Nm | 459 Nm meets or exceeds |
| Peak torque | 4.2 Nm | — |
| Ratio (max) | 850.3:1 | 1,000:1 meets or exceeds |
| Backlash (lower is better) | 114 arcmin | — |
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 | R22HT planetary gearhead | AD / ADR / ADS |
|---|---|---|
| Rated torque | 3.7 Nm | — |
| Peak torque | 4.2 Nm | — |
| Ratio (max) | 850.3:1 | — |
| Backlash (lower is better) | 114 arcmin | 1 arcmin meets or exceeds |
High-precision round-flange planetary with high input speed capability and near-zero backlash, aimed at robotics and CNC.
| Published maximum | R22HT planetary gearhead | WAE |
|---|---|---|
| Rated torque | 3.7 Nm | — |
| Peak torque | 4.2 Nm | — |
| Ratio (max) | 850.3:1 | — |
| Backlash (lower is better) | 114 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 Portescap R22HT planetary gearhead
Send these with your enquiry and an engineer can confirm the right R22HT planetary gearhead 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
Portescap R22HT planetary gearhead: frequently asked questions
Can you help replace Portescap R22HT planetary gearhead 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 supply-network options where appropriate. We confirm compatibility and any changes needed before recommending a replacement.
What is the Portescap R22HT planetary gearhead?
All-metal high-torque version of the 22 mm planetary gearhead, ratios 10.9:1 to 850.3:1 in 2 to 4 stages, up to 3.7 Nm continuous and 4.2 Nm static with 62–82% efficiency. Published series figures include outer diameter 22 mm, rated torque 3.7 Nm, peak torque 4.2 Nm, ratio 10.9:1. It is made by Regal Rexnord; Specify Motion can help source it or propose an equivalent.
Who makes the Portescap R22HT planetary gearhead?
The Portescap R22HT planetary gearhead is made by Portescap (Regal Rexnord) and is listed here for engineers comparing options. Specify Motion is not affiliated with Regal Rexnord; brand names are used only to identify the product.
What is the outer diameter of the Portescap R22HT planetary gearhead?
The published series maximum outer diameter is 22 mm. Individual models and sizes in the R22HT planetary gearhead 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 Portescap R22HT planetary gearhead?
We can assess suitable replacement options. On published figures, APEX Dynamics P-II / P-IIR and APEX Dynamics AD / ADR / ADS 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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