What forces are acting on bar BC in a gear wheel assembly?

[izzyosman]

Homework Statement

Gear wheels B and D are mounted on a right-angled carrier, C.
They mesh with a fixed gear wheel A, of radius 200mm. Each of the small wheels has a mass of 3kg and a radius of 100mm and may be considered to be a uniform circular disc. The carrier, which is freely pivoted about O, has a total mass of 6kg and may be considered as two uniform rods, each of legnth, 300mm.

The assembly is released from rest with the centre of B vertically above O. Find the angular velocity of the small wheels when the centre of D just reaches the point vertically below O.

http://twitpic.com/mpa24

Homework Equations

Rotational and Translation Impulse-Momentum Equations

The Attempt at a Solution

I'm just starting to attempt this question by looking at the bars separately. In the case of bar BC, I am not quite sure what force are acting on the bar apart from its weight.
Is there a force exerted by the gear B?

This leads me to wonder what to put in the equation:
work done=change in ke for the rotational component.

I know the right hand side would be 1/2 I(Theta dot2^2 - 0)

Please help!

 

[izzyosman]

come on guys! nobody ever replies to my questions..

 

[calimechengr]

You state each object in terms of "A,B,C,..." You may have a better chance if you provide a diagram for your question.

 

[izzyosman]

if you right click on the box under what i typed it will go to a twitpic page with the diagram.