Roller screw actuator
Exlar KX Series roller screw actuator
Mid-force motorless planetary roller-screw actuator in three frame sizes that works with servo, stepper or DC motors via inline or parallel mounts, often used to replace pneumatic cylinders.
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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
| Ingress protection | IP54S standard; IP65S with inline or parallel motor mount |
|---|---|
| Temperature | 0–65 °C |
| Force (max) | 15,600 N |
| Stroke (max) | 1,200 mm |
| Linear speed (max) | 833 mm/s |
| Screw lead | 5, 10 |
| Screw type | planetary roller screw |
| Sizes | KX60 (60 mm): 6.0 kN (5 mm lead) / 3.0 kN (10 mm lead); 417 / 833 mm/s; 5,000 rpm max input, KX75 (75 mm): 11.0-11.1 kN (5 mm) / 5.6 kN (10 mm); 333 / 666 mm/s; 4,000 rpm, KX90 (90 mm): 15.6 kN (5 mm) / 7.8 kN (10 mm); 250 / 500 mm/s; 3,000 rpm |
Summarised in our own words from Curtiss-Wright Actuation Group's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1 · Source 2 · Source 3
Notes on this data
Metric as printed. Stroke conflict: standard strokes 150/300/600/900 mm in product-page table, but features list and catalog ordering code include 1200 mm (48 in); catalog says consult sales for max allowable stroke. KX75 shown as 11.1 kN on page and 11.0 kN in catalog. Extended temperature -30 to 65 C (consult factory); storage -40 to 85 C. Backlash 0.10 mm; lead error G9 200 um/1000 mm. Forces are 'maximum force' (routine), not continuous.
Specify Motion is not affiliated with Curtiss-Wright Actuation Group. Exlar and KX Series are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Exlar KX 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 Exlar part. Published series figures do not establish an exact-model or drop-in replacement: confirm ratings, fit, interfaces and approvals for your application.
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.
| Published maximum | KX Series | RSA-HT (high thrust) |
|---|---|---|
| Force | 15,600 N | 58,000 N meets or exceeds |
| Stroke | 1,200 mm | 1,524 mm meets or exceeds |
| Speed | 833 mm/s | 3,124 mm/s meets or exceeds |
General-purpose electric rod actuator in six sizes with solid, bronze or ball screws and inline or reverse-parallel motor mounting; a broad pneumatic/hydraulic replacement workhorse.
| Published maximum | KX Series | RSA-ST (standard thrust) |
|---|---|---|
| Force | 15,600 N | 17,917 N meets or exceeds |
| Stroke | 1,200 mm | 1,524 mm meets or exceeds |
| Speed | 833 mm/s | 3,124 mm/s meets or exceeds |
Compact C7 ballscrew linear module with built-in guide, matched to 100-400 W servo motors from the main Japanese and Taiwanese brands.
| Published maximum | KX Series | BLM Built-in Linear Module |
|---|---|---|
| Force | 15,600 N | — |
| Stroke | 1,200 mm | 1,250 mm meets or exceeds |
| Speed | 833 mm/s | 1,600 mm/s 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.
Exlar KX Series model codes
Published model codes in the KX Series range, with key figures from the manufacturer's data. Search this page for your part number, or send it to us for availability or an equivalent.
| Model code | Max continuous force (N) | Max stroke (mm) | Max speed (mm/s) | Pricing / replacement |
|---|---|---|---|---|
| KX60 | 6000 | 900 | 833 | Quote or replacement for KX60 → |
| KX75 | 11100 | 900 | 666 | Quote or replacement for KX75 → |
| KX90 | 15600 | 900 | 500 | Quote or replacement for KX90 → |
Typical applications
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 Exlar KX Series
Send these with your enquiry and an engineer can confirm the right KX Series 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
Exlar KX Series: frequently asked questions
Can you help replace Exlar KX 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 supply-network options where appropriate. We confirm compatibility and any changes needed before recommending a replacement.
What is the Exlar KX Series?
Mid-force motorless planetary roller-screw actuator in three frame sizes that works with servo, stepper or DC motors via inline or parallel mounts, often used to replace pneumatic cylinders. Published series figures include temperature 0 °C, temperature 65 °C, force 15,600 N, stroke 1,200 mm. It is made by Curtiss-Wright Actuation Group; Specify Motion can help source it or propose an equivalent.
What model codes are in the Exlar KX Series range?
The KX Series range includes KX60, KX75, KX90. The table on this page lists each published model code with its key figures. Send us the code you use, or the one you need to replace, and our engineers will confirm availability, lead time or the closest equivalent.
Who makes the Exlar KX Series?
The Exlar KX Series is made by Exlar (Curtiss-Wright Actuation Group) and is listed here for engineers comparing options. Specify Motion is not affiliated with Curtiss-Wright Actuation Group; brand names are used only to identify the product.
What is the temperature of the Exlar KX Series?
The published series minimum temperature is 0 °C. Individual models and sizes in the KX 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 Exlar KX Series?
We can assess suitable replacement options. On published figures, Tolomatic RSA-HT (high thrust) and Tolomatic RSA-ST (standard thrust) are options to assess 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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