mirror landing gear

I’ve a landing gear of an airplane and need to mirror it to the other side. The landing gear has armatures for animation. Now how to mirror this whole construct without messing all up?
Many thanks

I’ve tried also for ex. only the wheels but as soon as I parent it the animation gets messed up.

I suppose that when you select all the objects and armatures belonging to this landing gear and create their “clone” (Alt-D) in a single operation, Blender will maintain their internal assignment. Then scale the root object (the parent of your hierarchy) by -1 along appropriate axis, to obtain a mirror copy of this assembly.
(The mirror operation also sets a negative scale)
However, the negative scale can also produce some strange effect for object constraints (if you are using any). Personally, I did it in the way described above. You can find details of this “mirroring” of the P-40 landing gear in section 8.5 of this book. (I suppose that when you take a look on the illustrations from its free version, you will better know what I mean).

Hmm the best I get is before attaching the wheels to the strut. As soon as I parent the wheel armatures to the strut armature the wheel doesn’t rotate smooth anymore. But it rotates fine before parenting. Thanks