How to Calculate the 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?

A certain screw jack has a pitch of 0.1cm and the diameter of the wheel to which the turning effect is set up is 50cm. If the efficiency of the jack screw is 40%, what must be the force applied to lift a load of 25,000N?

Calculation of the Force Required to Lift a Load Using a Screw Jack

A force of approximately 39.77 N must be applied to lift a load of 25,000 N, given the specified pitch of the screw jack and the efficiency of 40%.

The pitch of a screw jack is the distance traveled by the load for each revolution of the screw. In this case, the pitch is given as 0.1 cm, which means that for each complete turn of the screw, the load is lifted by 0.1 cm. The diameter of the wheel to which the turning effect is set up is given as 50 cm, which means that the circumference of the wheel is 50 cm x pi = 157.08 cm.

The efficiency of the jack screw is given as 40%, which means that the actual force required to lift the load is 1/0.4 = 2.5 times the ideal force. Therefore, the ideal force required to lift the load of 25,000 N is:

Ideal force = Load / Mechanical Advantage

The mechanical advantage of a screw jack is given by the formula:

Mechanical Advantage = circumference of wheel / pitch of screw

Substituting : Mechanical Advantage = 157.08 cm / 0.1 cm = 1570.8

Ideal force = 25,000 N / 1570.8

Ideal force = 15.91 N (to two decimal places)

The actual force required to lift the load is 2.5 times the ideal force:

Actual force = 2.5 x 15.91 N

Actual force = 39.77 N (to two decimal places)

By understanding the formula and calculation, you can determine the force required to lift a specific load using a screw jack efficiently.