The picture below is a trapdoor installed horizontally with a length and width of 80 cm. Its weight is 40kg.

Choose the suitable stroke:

We recommend that you install the bottom and head of the linear actuator at a distance of about 40cm vertically and horizontally from the fulcrum of the trapdoor. In this way, the initial installation distance between the head and the bottom of the linear actuator can be calculated to be 57CM. When the trapdoor is opened 90 degrees upward, the distance between the head and the bottom of the linear actuator after stretching can be calculated to be 80CM.

80CM – 57CM = 23CM

So the minimum stroke of this linear actuator needs to be greater than 23CM or 230MM, and its minimum installation distance should be greater than 57CM.

Choose the suitable speed:

The motion stroke of the linear actuator is 230MM, if you want to open the door in about 10 seconds, you can choose a linear actuator with a speed of 25mm/s. If you want to open the door in about 20 seconds, you can choose a linear actuator with a speed of 10mm/s.

Choose maximum thrust:

The mechanical analysis of the trapdoor is as follows in the figure :

1. The gravity G (40kg) of the trapdoor acts at a distance of 40CM from the hinge, its orientation is vertically downwards.

2. If you want to open the trapdoor, you need to apply a vertical upward pulling force F (Up) at the same 40CM, which needs to be greater than 40kg.

3. The thrust direction of the linear actuator to the trapdoor is obliquely to the upper right. The calculation formula of this F (Thrust) is as follows:

(40kg×57CM)/40CM=57kg

57kg is the minimum thrust required by the linear actuator, but we recommend that the linear actuator work at about half of its maximum load to obtain a longer working life, so we need to choose a linear actuator with a maximum thrust of more than 100kg.

Based on these three data, we recommend to choose the linear actuator with model 0041515. Here is the product link,

**https://www.electric-linear-actuators.com/products/16-400mm-12v-24v-electric-linear-actuator-max-thrust-1300ibs-6000n-600kgs-model-0041515**

You can choose the speed as 9mm/s, 18mm/s or 25mm/s according to your needs.

If the bottom of the linear actuator is installed at a position of 10 cm longitudinally from the fulcrum of the door, and the head of the linear actuator is installed at a position of 40 cm laterally from the fulcrum of the door. The picture below is a installation schematic.

Choose the suitable stroke:

The initial installation distance between the head and the bottom of the linear actuator can be calculated to be 42CM. When the trapdoor is opened 90 degrees upward, the distance between the head and the bottom of the linear actuator after stretching can be calculated to be 50CM.

50CM – 42CM = 8CM

So the minimum stroke of this linear actuator needs to be greater than 8CM or 80MM, and its minimum installation distance should be greater than 42CM.

Choose the suitable speed:

The motion stroke of the linear actuator is 80MM, if you want to open the door in about 10 seconds, you can choose a linear actuator with a speed of 8mm/s. If you want to open the door in about 20 seconds, you can choose a linear actuator with a speed of 4mm/s.

Choose maximum thrust:

The mechanical analysis of the trapdoor is as follows in the figure :

1. The gravity G (40kg) of the trapdoor acts at a distance of 40CM from the hinge, its orientation is vertically downwards.

2. If you want to open the trapdoor, you need to apply a vertical upward pulling force F (Up) at the same 40CM, which needs to be greater than 40kg.

3. The thrust direction of the linear actuator to the trapdoor is obliquely to the upper right. The calculation formula of this F (Thrust) is as follows:

(40kg×42CM)/10CM=168kg

168kg is the minimum thrust required by the linear actuator, but we recommend that the linear actuator work at about half of its maximum load to obtain a longer working life, so we need to choose a linear actuator with a maximum thrust of more than 300kg.

Based on these three data, we recommend to choose the linear actuator with model 0041532. Here is the product link,

**https://www.electric-linear-actuators.com/products/10-250mm-12v-24v-electric-linear-actuator-max-thrust-1300ibs-6000n-600kgs-model-0041532**

You can choose the speed as 5mm/s or 9mm/s according to your needs.