How to Calculate Force Required to Lift a Load Using a Screw Jack

What is the formula to calculate the force required to lift a load using a screw jack?

Given a screw jack with specific dimensions, how can you determine the force needed to lift a load?

Formula to Calculate Force Required

When dealing with a screw jack like the one shown with 8 pin-connected links and a center screw, the formula to calculate the force required to lift a load is:

F = W sin(θ) / 8

In the case of the given screw jack, each of the 8 pin-connected links is 350 mm long, 30 mm wide, and 2 mm thick, made from carbon steel. The center screw is 15 mm in diameter and also made from carbon steel. Now, let's calculate the force needed to lift a load of 10 kN using this screw jack.

The weight of the load, W, is given as 10 kN, which is equal to 10000 N. For any angle of the screw jack, denoted by θ, the formula to determine the force required simplifies to F = 10000 × sin(θ) / 8.

Let's take an example where the angle θ is 45°:

F = 10000 × sin(45°) / 8

F = 10000 × 0.7071 / 8

F = 884.4 N

Therefore, when the screw jack is positioned at an angle of 45°, the force required to lift the load is 884.4 N.