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I have a ramp (mass 2015kg of uniform size) hinged at one end lowered by cables (2) through a sheave 2.7m Vertical. The anchor point on the ramp is 2.7m from the hinge. The overall length of the ramp is 3.3m

What I would like to know is what force is required to lift the door at varying angles?

I have put the information below into a spreadsheet so I can just change (a) thinking it would calculate the force on any angle I entered.

What I know does not work is the formula for C. I have tested the formula against pythag theory(with a =90 degrees) and the length of cable(C) is not the same. Also at angles above 90 degrees the cable length gets shorter?

T=W*L*C/(2*A*B)

W=weight of Door (N)(ton*9.1) 18336.5

L=distance to mass centre of flap(m) 2.6

A=height of cable top from hinge(m) 2.7

B=distance from hinge to anchor on door(m) 2.7

C=Length of cable

**4.235063**

a= angle of open flap to vertical 110

T= 13.8481617 Kn

1.52177601 Te

Any help would be greatly appreciated