Rodless screw actuator
SMC LEJS rodless screw actuator
High-rigidity ball screw slider with AC servo motor in sizes 40 and 63; series maximum 85 kg horizontal load, 1,800 mm/s and 1,500 mm stroke at +/-0.01 mm repeatability.
Key specifications
| Stroke (max) | 1,500 mm |
|---|---|
| Linear speed (max) | 1,800 mm/s |
| Screw lead | 8 to 30 |
| Repeatability | 0.01 mm |
| Payload (max) | 85 kg |
| Motor | AC servo |
| Acceleration | 20,000 mm/s2 max |
Summarised in our own words from SMC Corporation's published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1 · Source 2
Notes on this data
LEJS100-X400 (made to order, 750 W) handles 400 kg horizontal at 500 mm/s and up to 2,300 mm/s with 50 mm lead; not included in series maxima.
Specify Motion is not affiliated with SMC Corporation. SMC and LEJS 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 a SMC 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.
Economical rodless screw actuator derived from the BC2 band cylinder, with solid-bearing rods and a stainless band seal for light to moderate loads.
| Published maximum | LEJS | BCS Rodless Screw (BCS/MCS) |
|---|---|---|
| Force | — | 11,700 N |
| Stroke | 1,500 mm | 3,048 mm meets or exceeds |
| Speed | 1,800 mm/s | — |
Screw-driven rodless actuator in six sizes, with a solid-bearing (S) or profiled-rail (P) carrier for moderate to heavy guided loads.
| Published maximum | LEJS | MXE Screw-Drive Rodless (MXE-S / MXE-P) |
|---|---|---|
| Force | — | 19,127 N |
| Stroke | 1,500 mm | 3,411 mm meets or exceeds |
| Speed | 1,800 mm/s | — |
Screw-driven rodless actuator with recirculating ball-bearing guidance integral to the extrusion, so it carries loads up to 35.6 kN (with carrier options) without external guides.
| Published maximum | LEJS | B3S Screw-Drive Rodless |
|---|---|---|
| Force | — | 12,010 N |
| Stroke | 1,500 mm | 4,547 mm meets or exceeds |
| Speed | 1,800 mm/s | 1,524 mm/s |
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 rodless screw actuator is
A rodless screw actuator moves a carriage along the actuator body using a ball or lead screw inside a profile. The load mounts directly on the carriage, which runs on guides, either internal bearings or profile rails, so the actuator carries and guides the load as well as moving it. A sealing band typically closes the slot along the body. The motor mounts at one end, inline or folded, and stroke is set by the body length.
When engineers choose a rodless screw actuator
Choose a rodless screw actuator when the load needs carrying along a guided path with good positioning accuracy and stiffness, such as in pick-and-place, gantries and positioning axes. Screw drive gives high thrust and precision. The trade-offs are speed and length: long screws hit critical speed limits, so long strokes run slower. For long, fast strokes with lighter loads, a belt-driven rodless actuator is usually better.
How to specify the SMC LEJS
Send these with your enquiry and an engineer can confirm the right LEJS variant or an equivalent:
- Payload mass and position offset (kg, mm)
- Moment loads on the carriage (Nm)
- Stroke (mm), speed (mm/s) and acceleration (m/s²)
- Thrust force needed (N)
- Repeatability (mm)
- Orientation: horizontal, vertical or wall-mounted
- Environment and sealing (IP code)
Common mistakes to avoid
- Ignoring moment loads from offset payloads
- Choosing a long stroke at high speed and exceeding screw critical speed
- Not adding a brake for vertical axes
- Assuming the sealing band keeps out fine dust or liquids
SMC LEJS: frequently asked questions
What is the SMC LEJS?
High-rigidity ball screw slider with AC servo motor in sizes 40 and 63; series maximum 85 kg horizontal load, 1,800 mm/s and 1,500 mm stroke at +/-0.01 mm repeatability. Published series figures include stroke 1,500 mm, linear speed 1,800 mm/s, repeatability 0.01 mm, payload 85 kg. It is made by SMC Corporation; Specify Motion can help source it or propose an equivalent.
Who makes the SMC LEJS?
The SMC LEJS is made by SMC (SMC Corporation) and is listed here for engineers comparing options. Specify Motion is not affiliated with SMC Corporation; brand names are used only to identify the product.
What is the stroke of the SMC LEJS?
The published series maximum stroke is 1,500 mm. Individual models and sizes in the LEJS 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 SMC LEJS?
Yes. On published figures, Tolomatic BCS Rodless Screw (BCS/MCS) and Tolomatic MXE Screw-Drive Rodless (MXE-S / MXE-P) are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
Is a belt or screw rodless actuator better?
A screw rodless actuator gives more thrust, stiffness and positioning accuracy, which suits pressing, vertical axes and precise positioning. A belt actuator is faster and handles longer strokes, which suits transfer and pick-and-place over distance. Many machines use both: belts for long horizontal moves and screws for shorter, precise or vertical axes.
What limits the speed of a screw-driven actuator?
Speed is limited by the screw's critical speed, the rotation at which it starts to whip. Critical speed falls sharply as unsupported length increases, so long strokes have lower maximum speeds. Screw supports, larger diameters or a coarser lead raise usable speed. Manufacturers publish speed against stroke curves that should be checked.
Further reading: Rodless belt vs screw actuators · How to size a linear actuator · Linear actuators
Other rodless screw actuator series
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