How to choose a linear actuator: load, stroke, speed and protection
A practical checklist for specifying an electric linear actuator, with the Dreamfusion datasheet figures worked in so you can check a fit in minutes.
Six questions that decide the actuator
Answer these before you ask for a quotation. Each one maps to a line on the datasheet.
1. What load must it move?
Estimate the worst-case force at the actuator, not just the weight of the load. The angle of your linkage and the lever arm change the force the actuator sees. Choose an actuator whose rated load is above that worst case, and never exceed the rated load: the datasheet safety note says so.
Datasheet ratings are dynamic load, meaning force while moving: 12000 N for the DF-LA-SL650 and 7000 N for the DF-LA-SL250. Static load, the force held at rest, is not on the datasheets and is confirmed in the quotation.
2. How far must it travel?
The stroke is the travel between the two end positions of the rod. Measure it on your mechanism and pick a stroke at least that long. Standard strokes are 635 mm (DF-LA-SL650, the 650 series) and 250 mm (DF-LA-SL250). A custom stroke is possible for OEM projects.
3. How fast must it move?
Both models run at 6 mm/s with no load and 4 mm/s at full load. Travel time is simply stroke divided by speed, as the table below shows.
| Model | Stroke | Free load, 6 mm/s | Full load, 4 mm/s |
|---|---|---|---|
| DF-LA-SL650 (650 series) | 635 mm | about 106 s | about 159 s |
| DF-LA-SL250 | 250 mm | about 42 s | about 63 s |
Calculated by dividing stroke by the datasheet speed. These are not measured figures and ignore start and stop. If you need faster travel than 6 mm/s, tell us on the contact page.
4. What supply do you have?
Both standard actuators use a 24 V BLDC motor (240 W on the SL650, 120 W on the SL250) with 3 Hall sensors, and a motor controller of Dreamfusion's exclusive design. The datasheets state a full-load current of up to 10 A, so size the 24 V supply for that.
5. Where will it be installed?
IP65 means the housing is dust-tight and protected against water jets under IEC 60529. The operating temperature range is -10 °C to 55 °C. If your site is outside that range, or the actuator will be submerged or washed down at high pressure, ask us before you choose.
6. How will it be mounted and controlled?
The SL650 has an M14 rod end bearing at both ends. The SL250 has a DIA14 square connector with an adjustable hole at both ends. Two limit switches are built in, and the Hall sensors give position feedback to the controller. If your mechanism needs different end fittings, cable length or controller interface, that is what the OEM service is for.
Which Dreamfusion actuator fits?
| Your need | Look at |
|---|---|
| Travel up to 635 mm, load up to 12000 N | DF-LA-SL650 (650 series) |
| Travel up to 250 mm, load up to 7000 N | DF-LA-SL250 |
| Solar tracker drive | Solar tracker actuator guide |
| Different stroke, fitting, cable or interface | OEM version |
Rated loads are dynamic loads from the Rev A.3 datasheets. Suitability for your application is always confirmed in the quotation.
Linear actuator specifications explained
Dynamic load
The force the actuator can push or pull while the rod is moving.
Static load
The force the actuator can hold while the rod is stationary. Not stated on our datasheets; confirmed in the quotation.
Stroke
The distance the rod travels between its fully retracted and fully extended positions.
Free-load and full-load speed
Rod speed with no load (6 mm/s) and at the rated load (4 mm/s) for both Dreamfusion models.
BLDC motor
A brushless DC motor. It has no carbon brushes, and an electronic controller switches the windings. Position of the rotor is read by Hall sensors.
Hall sensor
A sensor that detects the rotor position of the BLDC motor. Both models have 3.
Limit switch
A switch that stops the rod at the end of its travel. Both models have 2 built in.
IP65
Ingress protection: 6 for dust-tight, 5 for protection against water jets (IEC 60529).
Rod end bearing
A swivelling joint at the end of the actuator that tolerates small angular movement. The SL650 uses an M14 rod end bearing at each end.
Duty cycle
How long the actuator can run in a given period before it needs to rest. Not stated on our datasheets; confirmed in the quotation.
Choosing a linear actuator: questions, answered
How do I choose a linear actuator?
Work through load, stroke, speed, supply voltage, protection rating and mounting, in that order. Write down the worst-case load, the travel between end positions, the speed you need, the 24 V supply you have, and where the actuator will be installed. Then compare those numbers with the datasheet.
What is the difference between dynamic load and static load?
Dynamic load is the force the actuator can push or pull while it is moving. Static load is the force it can hold when it is not moving. Dreamfusion datasheets state the dynamic load (12000 N for the DF-LA-SL650, 7000 N for the DF-LA-SL250). Static load is confirmed in the quotation.
How many kilograms is 12000 N?
About 1224 kgf, since 1 kgf is 9.80665 N. This is the force rating, not a recommendation to lift a given mass, because the geometry of your mechanism changes the force the actuator sees.
What does IP65 mean?
IP65 means dust-tight (6) and protected against water jets (5) under IEC 60529. It is not a rating for submersion. Both Dreamfusion actuators are IP65.
What stroke length do I need?
The stroke is the distance the rod travels between its two end positions. Measure the travel your mechanism needs between end positions and choose a stroke at least that long. Our standard strokes are 635 mm (DF-LA-SL650, 650 series) and 250 mm (DF-LA-SL250).
Can I get a stroke that is not standard?
Yes, for OEM projects. Send your travel, load and voltage on the OEM and export page route and we will confirm what is possible.
Do I need a 24 V supply?
Both standard models run on a 24 V BLDC motor. The datasheets state a full-load current of up to 10 A, so size your supply for that.
Not sure which actuator fits?
Send your load, travel and voltage on WhatsApp and we will suggest a standard model or an OEM version.