When customers ask which actuator to buy, the first question is usually “how much thrust do I need?” Choosing a unit by the weight of the object alone is the most common mistake: it either stalls or runs hot because the motor is overloaded. Calculating electric linear actuator thrust means converting the real load on the mechanism into a force along the actuator axis, then adding a sensible safety margin.

1. Rated thrust versus real load

Rated thrust is the maximum axial force the actuator can hold under standard conditions, measured at rated voltage and stroke. The real load is the resistance the mechanism presents: the gravity component of the moving part, friction in guides and hinges, starting inertia and the mechanism’s own losses. They are not the same. A 2000 N actuator can fail to move a few hundred newtons if the linkage is badly placed, so start from the mechanism, not the label.

2. Working out the required thrust

The classic case is a lid pivoting on a hinge. If the lid weighs G, its centre of gravity sits a horizontal distance L from the hinge, and the actuator pushes at a perpendicular distance d, the thrust needed is roughly F = G × L ÷ d, plus friction and inertia. Mount the actuator closer to the hinge and the lever arm d gets shorter, so the required thrust rises. Lifting straight up, thrust must at least equal the weight; pushing at an angle, divide by the sine of the working angle, and a shallow angle multiplies the force. Reduce every factor to one number along the actuator axis first.

3. Lever arm and mounting angle

The same actuator can move very different loads depending on where it is mounted. Close to the hinge, or near the dead point of the stroke, the lever arm is short and efficiency drops. Lay out the mechanism so the actuator works close to perpendicular through most of its travel, and avoid extreme angles at either end. Once the geometry is fixed you can work back to the thrust you need, which is why we fix the linkage sketch before choosing the model. If the angle changes a lot over the stroke, check the worst point.

4. Choosing a safety factor

After calculating the theoretical thrust, add a safety factor. For indoor, steady loads with infrequent movement, 1.2 to 1.5 is usually enough. Where there is shock, vibration, wind load outdoors or frequent starting and stopping, 1.5 to 2.0 is safer. A generous margin keeps the motor away from full load, which lowers heat and noise and extends life. Do not overdo it: more thrust usually means a bigger motor and higher current, loading the power supply and controller. LOUIE Electric Linear Actuator checks weight, lever arm, working angle and cycle frequency before recommending a model.

5. Common mistakes

Four come up repeatedly. Using a static weight and ignoring inertia and wind, so the starting shock is far larger than expected. Treating rated thrust as the machine’s limit and forgetting the lever arm. Ignoring the link between speed and thrust, since the same model delivers less force at higher speed. And ignoring holding: equipment that must stay part way through a stroke needs a self-locking model that keeps position when power is removed.

6. Conclusion

Thrust calculation comes down to three steps: work out the real load, convert it to the actuator axis through the lever arm and angle, and apply a sensible safety factor. Do that, check the result against the linkage, and selection stops being guesswork.