Scissor Lift Formula

[djjosh56]

I work in automation in the theatre industry and I recently set myself the task of creating a scissor lift/ table from scratch, I’m hoping it will lift 60KG about 500mm.

I’m struggling to find the correct formulas for working out the force needed to active the scissor lift at different points, e.g the bottom middle or top. I’m hoping someone could point me in the correct direction, please.

I have found the formula:
F=(W+WA/2) / Tan (A)
Where as:
W = Weight of load
WA = Weight of arm
A= Angles of arms to the ground

However I do not understand where the force calculated should be applied on the scissor lift arm?

Additionally, I have found the formula:
The sum of the movement of A = FA X (L/2 x Cos Alpha) - ( F x (L X Cos Alpha)
Where as:
FA = Force on actuator
L= length of leaver
Alpha = angle of leaver.

I believe this formula gives me the force on an actuator vertical to a leaver, unfortunately I don’t know how to change this so the actuator doesn’t have to be vertical.

I would greatly appreciate any help in finding the correct formulas.

I’m enjoying learning about this new subject and would love to know what books or reference material you would recommend for future projects.

I appreciate you taking the time to read this, any guidance would be greatly appreciated.

[Kelly_Bramble]

The formulas are dependent on the configuration of the scissor jack. The resultant loading is determined by statics analysis and each jacj configuration is different.

There are two configurations with formulas on Engineers Edge here.

https://www.engineersedge.com/mechan...issor-lift.htm

If you need a different configuration then you will need modeling software or knowledge of statics.

Other resources:

Scissor Lift Design and Analysis Equations