# Mechanical Advantage of a 4-bar

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1. Nov 3, 2014

### gocomando

Alright, the problem at a glance is rather simple: find the mechanical advantage at two given values of θ2.

Given:
rO2A = r2
r02C = rin
rAB = r3
rO4B = r4
rO4D = rout
rO2O4 = r1
θ1 = 135°

Find:
Mechanical advantage when θ2 is equal to 104°, and when θ2 is equal to 91°.

Equations to use:
Mech advantage = (rin/rout) * (ωin/ωout) (I think this is the one I'm supposed to use)

EDIT: Turns out we're allowed to simply measure the actual angle provided in the problem. Now, since this 4-bar is inverted, how exactly do I measure the angle θ3 andθ4?

EDIT: I believe I'm supposed to measure from the positive x-axis counterclockwise until I get to the link. Using this, I got θ3= -57 and θ4 = 187. From here though, how might I find (ωin/ωout)? I have the vector loop equation R2 + R3 = R4 + R1, and when I get the corresponding velocity equations, R4 is in there making things complicated.

Last edited: Nov 3, 2014
2. Nov 8, 2014