A ski tow, also called rope tow or handle tow, is a mechanised system for pulling skiers and snowboarders uphill.
In its most basic form, it consists of a long rope loop running through a bullwheel (pulley) at the bottom and one at the top, powered by an engine at one end. Passengers grab hold of the rope and are pulled along while standing on their skis or snowboards and sliding up the hill, with some variations having simple fixed handles. These simple forms remain popular for the relatively flat portions of ski areas devoted to beginners—often called bunny slopes—but are increasingly being replaced by magic carpets.
The more advanced form uses a series of pulleys to follow the slope, and can be up to 1.4 km long tow with a 600 metre vertical rise. The forces involved and the pulleys which the rope passes through require the rider to attach using a "nutcracker" or "tow grabber". This style has now been superseded by T-bar lifts, platter lift and chairlift in most places—with the notable exception of the smaller club fields of New Zealand.
source: Wikipedia, the free encyclopedia