Roller screw actuator
Ewellix SRSA / SVSA / SLSA roller screw actuator
High-performance roller screw actuators: SRSA uses a planetary roller screw, SVSA a recirculating roller screw for low pitches and SLSA a recirculating roller screw for high pitches, with in-line or parallel motor, optional brake, Pt100 sensor and automatic lubrication.
Key specifications
| Temperature | 0–40 °C |
|---|---|
| Screw type | planetary (SRSA) or recirculating (SVSA, SLSA) roller screw |
| Options | in-line or parallel motor, gear, screw brake, Pt100, automatic lubrication |
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
User manual BA 125 (2026-03) gives no force, speed or stroke figures; these are application-engineered and quoted per drawing. Temperature is operating ambient.
Specify Motion is not affiliated with Schaeffler AG. Ewellix and SRSA / SVSA / SLSA 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 an Ewellix 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.
Heavy-duty version of the RSA rod actuator with roller-screw options, matched angular-contact bearings and larger motor mounts, reaching 58 kN on size 64.
View RSA-HT (high thrust) →High-force planetary roller-screw (and ball-screw) rod actuator from 89 kN (RSX10) up to 445 kN (100,000 lbf, RSX50) series maximum, positioned as a direct hydraulic cylinder replacement, with oil-cooled and food-grade versions.
View RSX Extreme Force →Tolomatic servo rod actuators for resistance spot-welding guns, listed only in the overview brochure.
View SWA/B Resistance Spot Welding and GSWA →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.
What a roller screw actuator is
A roller screw actuator is a rod actuator driven by a planetary roller screw instead of a ball screw. Threaded rollers sit between the screw and nut, so the load is spread across many line contacts rather than a limited number of balls. This gives much higher load capacity, stiffness and shock resistance in the same envelope, and typically several times the life of a ball screw of similar size. Inverted designs place the rollers on the rod, allowing the motor rotor to drive the nut directly.
When engineers choose a roller screw actuator
Choose a roller screw actuator for high forces, long life, heavy duty cycles or shock loads, such as presses, welding guns, test rigs and hydraulic replacement. The trade-offs are cost, which is higher than an equivalent ball screw, and lower efficiency at very fine leads. For moderate loads and duty, a ball screw is usually more economical. Roller screws also tolerate higher accelerations and speeds at a given diameter, which helps compact high-force designs.
How to specify the Ewellix SRSA / SVSA / SLSA
Send these with your enquiry and an engineer can confirm the right SRSA / SVSA / SLSA variant or an equivalent:
- Peak and continuous force (N or kN)
- Full motion profile with dwell times
- Required life (km or cycles)
- Stroke (mm) and speed (mm/s)
- Shock or impact loads
- Mounting and side-load conditions
- Lubrication method and environment
Common mistakes to avoid
- Choosing a roller screw when duty and load would let a ball screw do the job
- Neglecting lubrication interval, which strongly affects roller screw life
- Calculating life on peak force instead of the cubic mean load
- Forgetting that motor and drive must also handle the peak force
Ewellix SRSA / SVSA / SLSA: frequently asked questions
What is the Ewellix SRSA / SVSA / SLSA?
High-performance roller screw actuators: SRSA uses a planetary roller screw, SVSA a recirculating roller screw for low pitches and SLSA a recirculating roller screw for high pitches, with in-line or parallel motor, optional brake, Pt100 sensor and automatic lubrication. Published series figures include temperature 0 °C, temperature 40 °C. It is made by Schaeffler AG; Specify Motion can help source it or propose an equivalent.
Who makes the Ewellix SRSA / SVSA / SLSA?
The Ewellix SRSA / SVSA / SLSA is made by Ewellix (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 temperature of the Ewellix SRSA / SVSA / SLSA?
The published series minimum temperature is 0 °C. Individual models and sizes in the SRSA / SVSA / SLSA 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 Ewellix SRSA / SVSA / SLSA?
Yes. On published figures, Tolomatic RSA-HT (high thrust) and Tolomatic RSX Extreme Force are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
Why are roller screws longer lasting than ball screws?
In a planetary roller screw, the load is carried across many line contacts on the threaded rollers, while a ball screw carries load through point contacts on a limited number of balls. Lower contact stress per point gives more load capacity and a longer fatigue life for the same size, typically several times longer at the same load.
When is a ball screw a better choice than a roller screw?
A ball screw is usually better value for moderate loads, normal duty and modest life targets, and it is more widely available in standard sizes and leads. Choose a roller screw when force, shock, stiffness or life requirements push a ball screw beyond a sensible size. Calculating life with the real cycle usually shows which applies.
Further reading: Ball screw vs roller screw · Hydraulic to electric actuator · Linear actuators
Other roller screw actuator series
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