The motion in a mechanism simulation is purely relative. The movement of a part is calculated with respect to other parts in the assembly, and not with respect to an external frame of reference. You can use a Fix engineering connection to prevent a part from moving in the external frame of reference. Other parts in the assembly move according to the fixed part. If there is not a Fix engineering connection in a mechanism, the mechanism simulation uses an arbitrary frame of reference. In the simple example of a two-part mechanism, you cannot control which part remains stationary and which part appears to move. To define a frame of reference, add a Fix engineering connection to the mechanism to explicitly identify the part that needs to remain stationary during the simulation. | |||||||