Swingarm bearing operation

[boostin]

What stops the inner bushes in a swingarm bearing from working their way up the swingarm spindle in the example below?

Is there a spacer tube on the spindle or something?

http://4.bp.blogspot.com/_xH-YGXZbazw/SUB0iRS4v0I/AAAAAAAADzc/IgJ60bcCYLY/s1600-h/IMG_2206.JPG

http://www.zimbio.com/Off+Roading+Fabrication,+Maintenance+and+Fun/articles/18/Replacing+Dirt+Bike+Swingarm+Bearings+CR250

Thanks.

[Katman]

The engine sits in the middle and the bushes butt up onto it.

[boostin]

Thanks. Wish I had just looked up a pic of a CR250 now, seems so obvious.

I assume it will be the same for the majority of swingarms that are designed that way? With the gap in the mount, as opposed to the solid end. Excuse the terminology.