depth of view in wireframe 2.49b

there are two complicated mechanisms one behind the other.
in wire frame mode how do i NOT see the back ones?
i tried in shaded etc with a plane between them. computer/blender could not process that.
i need to work on the front movement but know i am not picking up the back one.
it is the wheels of an old train.
4 wheels etc behind another set of 4 then the same over the other side of the train.
thanks all


BIGBOYgears.blend (953 KB)