Frameless torque motor
Schaeffler RKI torque motors (IDAM)
Water-cooled high-speed frameless torque motors from Schaeffler's IDAM unit in seven sizes (168 to 920 mm air-gap diameter), with series maxima of about 11,864 Nm continuous, 17,670 Nm peak and up to 3,000 rpm.
Need this part, a replacement or a complete package? Our experienced UK engineering team helps you select, source and obtain the right products, with pricing, delivery coordination and after-sales support.
Pricing and availability
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Need Schaeffler parts, a replacement or a suitable alternative? Send us a part number, or tell us what the machine needs to do. Our UK engineers will come back with the right product, pricing, lead time and delivery, whether that is the original part, a checked alternative or a complete axis.
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What are you specifying?
Select everything you need. A motor, drive and gearbox can be specified together as one axis.
Key specifications
| Voltage (max) | 650 V |
|---|---|
| Peak torque (max) | 17,670 Nm |
| Continuous torque (max) | 11,864 Nm |
| Speed (max) | 3,000 rpm |
| Sizes | RKI11-168, RKI5-230, RKI11-298, RKI5-384, RKI11-460, RKI11-690, RKI11-920 |
| Cooling | Water (standard) |
Summarised in our own words from Schaeffler AG's published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
Continuous torque is Tcw1 (water-cooled). Max speed range 364-3,000 rpm by size and winding. Catalogue RE1 quotes RKI/RKIB peak torque up to 25,000 Nm.
Specify Motion is not affiliated with Schaeffler AG. Schaeffler and RKI torque motors (IDAM) are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Engineer support
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Our experienced engineers are on hand, ready to help with your project. Whether you need the Schaeffler RKI torque motors (IDAM) itself, help sourcing it, or a modified or custom design built around your load, speed and space, tell us what the machine has to do and we'll come back with the right option.
- Help sourcing RKI torque motors (IDAM) and spares for installed machines
- Modified and custom designs when a catalogue part doesn't fit
- Complete axis: motor, drive, gearing and feedback matched together
Typical applications
What a frameless torque motor is
A frameless torque motor is a permanent-magnet brushless motor supplied as two parts, a rotor and a stator, with no housing, bearings or shaft. The machine builder mounts the rotor directly on the driven shaft and the stator in the machine structure, so the motor becomes part of the mechanism. Many have large through-holes and high pole counts, giving high torque at low speed with no gearbox. They need separate feedback, typically an encoder, and a servo drive.
When engineers choose a frameless torque motor
Choose a frameless motor when you want direct drive in a compact, integrated design, such as robot joints, gimbals, rotary tables and medical devices. Removing the gearbox eliminates backlash and improves stiffness and smoothness. The trade-offs are integration work and size: the builder supplies bearings, alignment, cooling and feedback, and torque per volume is lower than a geared solution. For off-the-shelf installation, a housed direct-drive motor may be simpler.
How to specify the Schaeffler RKI torque motors (IDAM)
Send these with your enquiry and an engineer can confirm the right RKI torque motors (IDAM) variant or an equivalent:
- Continuous and peak torque (Nm)
- Speed (rpm)
- Outer diameter, bore and stack length (mm)
- Bus voltage and current (V, A)
- Thermal mounting and cooling
- Feedback type and resolution
- Air gap and concentricity tolerance (mm)
Common mistakes to avoid
- Leaving air gap and concentricity tolerances undefined
- Ignoring heat conduction from the stator into the housing
- Using an encoder with too low resolution for direct drive
- Forgetting rotor magnet attraction during assembly
Schaeffler RKI torque motors (IDAM): frequently asked questions
Can you help replace Schaeffler RKI torque motors (IDAM) 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 Schaeffler RKI torque motors (IDAM)?
Water-cooled high-speed frameless torque motors from Schaeffler's IDAM unit in seven sizes (168 to 920 mm air-gap diameter), with series maxima of about 11,864 Nm continuous, 17,670 Nm peak and up to 3,000 rpm. Published series figures include voltage 650 V, peak torque 17,670 Nm, continuous torque 11,864 Nm, speed 3,000 rpm. It is made by Schaeffler AG; Specify Motion can help source it or propose an equivalent.
Who makes the Schaeffler RKI torque motors (IDAM)?
The Schaeffler RKI torque motors (IDAM) is made by Schaeffler (Schaeffler AG) and is listed here for engineers comparing options. Specify Motion is not affiliated with Schaeffler AG; brand names are used only to identify the product.
What is the voltage of the Schaeffler RKI torque motors (IDAM)?
The published series maximum voltage is 650 V. Individual models and sizes in the RKI torque motors (IDAM) 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 Schaeffler RKI torque motors (IDAM)?
We can assess suitable replacement options. Our engineers can review the original model and propose options for your load, speed and environment. An engineer confirms the fit against your application before recommending anything.
What is the difference between a frameless and a housed torque motor?
A frameless motor is only a rotor and stator; the machine provides bearings, shaft, housing and feedback. A housed direct-drive motor adds bearings, housing and encoder in a ready-to-install unit. Frameless suits compact, integrated designs where the machine already has stiff bearings; housed suits faster installation and simpler alignment.
Why use a frameless motor instead of a gearbox?
Direct drive removes backlash, wear and compliance in the gear train, giving smoother motion and stiffer control. It also allows a large hollow shaft for cabling. The trade-off is that torque must come from the motor alone, so it is larger for a given torque.
Further reading: How to select a frameless torque motor · Frameless motor sizing robot joints · Frameless and torque motors
Other frameless torque motor series
Engineer support
Our engineers are ready to help with your project
Tell us about your project and how you use the Schaeffler RKI torque motors (IDAM): the load, speed, duty and environment. An experienced engineer will review it and reply, normally within one working day.
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Prefer to configure it? Use the spec builder.
How it works
From enquiry to delivery
Send a part number or describe the application. Our engineers take it from there: the right product, a clear quotation, and delivery and support arranged.
- 01Tell us what you needSend a part number, or configure the application, quantities and timing.
- 02An engineer reviews itWe check the specification and find the original part, a checked equivalent or a complete axis.
- 03Receive your quotationProducts, pricing, lead time and compatibility notes in one reply.
- 04Order and deliveryWhen you are happy, the order is placed and delivery and after-sales support are arranged.