Rodless belt actuator
SMC LEJB rodless belt actuator
High-rigidity belt-drive slider with AC servo motor in sizes 40 and 63; series maximum 3,000 mm/s, 3,000 mm stroke and 30 kg horizontal load.
Key specifications
| Stroke (max) | 3,000 mm |
|---|---|
| Linear speed (max) | 3,000 mm/s |
| Screw lead | 27 (size 40), 42 (size 63) per rev |
| Payload (max) | 30 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
Specify Motion is not affiliated with SMC Corporation. SMC and LEJB 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.
Wide steel-cord urethane belt version of the B3 rodless actuator for long, fast strokes up to 14.6 m and 5 m/s with integral bearing guidance.
| Published maximum | LEJB | B3W Belt-Drive Rodless |
|---|---|---|
| Force | — | 1,446 N |
| Stroke | 3,000 mm | 14,579 mm meets or exceeds |
| Speed | 3,000 mm/s | 5,080 mm/s meets or exceeds |
Belt-driven rodless actuator in six sizes for long, fast strokes, offered unguided (U), with self-cleaning solid bearings for dusty sites (S), or on profiled rail for heavy loads (P).
| Published maximum | LEJB | MXB Belt-Drive Rodless (MXB-U / MXB-S … |
|---|---|---|
| Force | — | 1,859 N |
| Stroke | 3,000 mm | 10,516 mm meets or exceeds |
| Speed | 3,000 mm/s | 5,080 mm/s meets or exceeds |
Steel-belt driven linear module with integral guide rail, intended as a long-stroke, high-speed replacement for pneumatic cylinders.
| Published maximum | LEJB | LB Belt-Drive Linear Actuator |
|---|---|---|
| Stroke | 3,000 mm | 3,050 mm meets or exceeds |
| Speed | 3,000 mm/s | 2,000 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 belt actuator is
A rodless belt actuator moves a carriage along an aluminium profile using a toothed belt driven by a pulley at one end. The load mounts on the carriage, which runs on internal bearings or profile rails, so the unit carries and guides the load. Because the belt does not whip like a long screw, stroke can be long, typically several metres, and speeds are high. Belt drives are less stiff than screws, so they suit fast transfer more than high-force pushing.
When engineers choose a rodless belt actuator
Choose a belt actuator for long strokes, high speed and lighter thrust loads, such as transfer axes, gantries and pick-and-place over distance. The trade-offs are stiffness, thrust and accuracy: belt stretch reduces stiffness and repeatability compared with screw drives, and vertical axes need a brake and careful sizing. For high thrust or tight positioning at short stroke, a screw rodless actuator is usually a better fit.
How to specify the SMC LEJB
Send these with your enquiry and an engineer can confirm the right LEJB variant or an equivalent:
- Payload mass and moment loads (kg, Nm)
- Stroke (mm or m)
- Speed and acceleration (m/s, m/s²)
- Positioning repeatability (mm)
- Thrust force needed (N)
- Orientation and any vertical axis requirements
- Motor mounting, gearbox and environment
Common mistakes to avoid
- Forgetting belt tension and stretch when tight repeatability is needed
- Using a belt actuator for pressing or high thrust tasks
- Ignoring reflected inertia and gearbox ratio on high-acceleration axes
- Mounting the profile unsupported over long spans
SMC LEJB: frequently asked questions
What is the SMC LEJB?
High-rigidity belt-drive slider with AC servo motor in sizes 40 and 63; series maximum 3,000 mm/s, 3,000 mm stroke and 30 kg horizontal load. Published series figures include stroke 3,000 mm, linear speed 3,000 mm/s, payload 30 kg. It is made by SMC Corporation; Specify Motion can help source it or propose an equivalent.
Who makes the SMC LEJB?
The SMC LEJB 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 LEJB?
The published series maximum stroke is 3,000 mm. Individual models and sizes in the LEJB 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 LEJB?
Yes. On published figures, Tolomatic B3W Belt-Drive Rodless and Tolomatic MXB Belt-Drive Rodless (MXB-U / MXB-S / MXB-P) are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
How long can a belt-driven linear actuator be?
Belt actuators commonly reach several metres of stroke from one profile, and longer strokes are possible with joined profiles. The limits are profile stiffness, belt stretch, support spacing and the moment loads on the carriage. Long axes need regular supports along their length to avoid sag.
How accurate is a belt-driven actuator?
Repeatability on belt actuators is typically in the region of a tenth of a millimetre, depending on belt type, tension and load, which is coarser than screw drives. Accuracy is affected by belt stretch and pulley tolerances. For better accuracy, add linear encoder feedback or choose a screw drive.
Further reading: Rodless belt vs screw actuators · How to size a linear actuator · Linear actuators
Other rodless belt actuator series
Spec builder
Specify what you need instead of LEJB
Select every part you need, answer the questions an applications engineer would ask, and see your summary before we ask for any details.
- 1Products
- 2Performance
- 3Environment
- 4Volumes
- 5Your spec
Engineer support
Let our experienced engineers do the hard work for you
Tell us how you use the SMC LEJB: the load, speed, duty and environment. Our engineers will confirm whether it is still the right part, find it for you, or propose an alternative that fits better.
- Reviewed by an engineer, not an autoresponder
- Like-for-like and better-fit alternatives
- Standard, modified and custom options
Prefer to configure it? Use the spec builder.