Modern Vespa

what exactly is the difference between sliders and rollers?
are they the same thing, just called dif. names..
I sort of understand what they are but have heard both terms...tia!
B

Both are forms of the weights that live in the variator portion of the CVT automatic transmission. The weights move in ramps cast into the aluminum half-pulley that forms the siding half of the drive pulley on the engine crankshaft. They are flung outward from the hub by centrifugal force as the engine revs and bear against a fixed steel plate as they move out their ramps, forcing the sliding half of the pulley against a fixed half, thereby increasing its effective diameter and creating a gradually higher gear ratio. The driven pulley at the rear wheel also has a movable half that is spring-loaded, and it automatically opens as the driving pulley closes.

Most variators have stock weights that are cylindrical in shape and which are generally referred to as "rollers" even though they really don't do much rolling as they move (since they bear against both the ramp and the backing plate). In fact, once they start to wear and develop flat spots, they don't roll at all. Not too many years ago, a company called Union Materials developed weight sets that are shaped to take advantage of the fact that the weights don't need to roll at all -- they are designed to slide with little friction and wear, and are shaped to allow the variator pulley to be pushed closed a bit farther when the weight reaches the end of the ramp. They are marketed under the "Dr. Pulley" brand. Here's a comparison in a video:
http://www.bing.com/videos/watch/video/dr-pulley-sliders-a-brief-explanation-distributed-by-mrp/5ef47cb8d0a43b594a535ef47cb8d0a43b594a53-193344177309?q=Dr.%20Pulley%20sliders&FORM=VIRE1

thats what I was thinking....swap-able items...one rolls, other slides..
Thanks!