Unbalanced Drive Shaft

From the page:

-- They're really just a simple casing with an unbalanced drive shaft and a motor, but for such an unassuming device, the vibrator has some tremendous taboos associated with it. Most of these prejudices hinge on packaging and purpose– the vibrator in a pager is the same basic device as its stimulating and lurid cousin, but suffers no stigma. But perhaps our society has its taboos misplaced– after all, the pager uses its mechanical oscillations for the questionable purpose of distracting drivers on high-speed motorways, whereas the "vibrator" was originally designed for a noble medical purpose: the treatment of hysteria. --