Restrict bar movement

[mekafime]

Hi
please, I need to restrict the movement in bar ... (I want it to move only in the direction of the red arrows)
The force is applied on the diagonals (bar 3-60 and bar 4-60)
Thanks.

 

[petb]

Assign local axes for joint 3 and 4 and then allow axial movement only.

 

[mekafime]

How?
Could u tell me the steps?

 

[mekafime]

I assined local axes and put forces , but I dont know how gives axial movement only