A cable pulley is a type of guiding wheel around which a woven cable, usually made of steel, can be wound. The pulley wheel will feature an axle to allow the wheel to spin, and the axle will usually be mounted to a frame that can be affixed to a solid object for stability and strength. The pulley wheel itself is usually made of a tough metal such as steel to prevent premature wear or other damage. The cable pulley wheel is usually grooved or scooped around its perimeter to provide a better guiding track for the cable.
The uses of a cable pulley can vary, though the system is usually designed to lift heavy weights or move heavy objects over a length. Woven cables are much stronger than belts or ropes in most cases, so they are better prepared to handle the weight of larger objects. It is not uncommon to find a cable pulley in an industrial setting such as a warehouse or factory, or any other setting that requires the regular movement of extremely heavy objects. The size of the cable and the pulley will dictate how much weight the system can handle, as well as the number of pulleys in the system.
A good example of a cable pulley system is a ski lift. This system uses two large pulley wheels, one at either end of the lift, and cable support towers in between the two pulley wheels to keep proper tension on the cable system. The pulley wheels of such a system are likely to be quite large, since the lift is likely to support an extremely large amount of weight, especially when weighed down with passengers.
Smaller cable pulley systems are common on weight lifting machines. Cables are more durable and will not stretch as much as ropes or belts, which is especially important when the cables will support large amounts of weight on a regular basis. The exercise machines may feature several pulleys to accommodate the motion of the exercise the machine, though most exercise machines only feature one or two pulleys per cable. The more pulleys present in the system, the more the weight becomes distributed, which is advantageous in most situations. On weight machines, however, the user will want to benefit as much as possible from higher weights, so adding pulleys to the lifting system can actually be counterproductive for the weight lifter.