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A lift hill, or chain hill, is an upward-sloping section of track on a roller coaster on which the roller coaster train is mechanically lifted to an elevated point or peak in the track. Upon reaching the peak, the train is then propelled from the peak by gravity and is usually allowed to coast throughout the rest of the roller coaster ride's circuit on its own momentum, including most or all of the remaining uphill sections. The initial upward-sloping section of a roller coaster track is usually a lift hill, as the train typically begins a ride with little speed, though some coasters have raised stations that permit an initial drop without a lift hill. Although uncommon, some tracks also contain multiple lift hills.
Lift hills usually propel the train to the top of the ride via one of two methods: a chain lift involving a long, continuous chain which trains hook on to and are carried to the top; or a drive tire system in which multiple motorized tires (known as friction wheels) push the train upwards. A typical chain lift consists of a heavy piece of metal called a chain dog, which is mounted onto the underside of one of the cars which make up the train. This is in place to line up with the chain on the lift hill.
The chain travels through a steel trough, and is normally powered by one or more motors which are positioned under the lift hill. Chain dogs underneath each train are engaged by the chain and the train is pulled up the lift. Anti-rollback dogs engage a rack (ratcheted track) alongside the chain to prevent the train from descending the lift hill. At the crest of the lift, the chain wraps around a gear wheel where it begins its return to the bottom of the lift; the train is continually pulled along until gravity takes over and it accelerates downhill. The spring-loaded chain and anti-rollback dogs will disengage themselves as this occurs.
The cable lift is a type of lift mechanism that was first used on Millennium Force at Cedar Point in Sandusky, Ohio. This type of lift has also been used for Kings Dominion's Intimidator 305 (being the fastest cable lift at 17 mph at a 45 degree angle), Holiday Park's Expedition GeForce, Walibi Holland's Goliath, Djurs Sommerland's Piraten (Europe's only "Mega-Lite"-model coaster by Intamin), La Qua's Thunder Dolphin, Hersheypark's Skyrush (being the fastest cable lift to date at 17 mph), and is used on the wooden roller coaster El Toro at Six Flags Great Adventure and Flying Aces at Ferrari World.
The cable lift utilizes a cable loop in place of the traditional chain, which is attached to a short section of chain that engages the train's chain hook. Because a cable is much lighter than a chain, cable lifts are much faster than chain lifts and can be used on much steeper hills - even vertical. A cable also requires far less maintenance than a chain. Another advantage to park guests is that a cable lift is very quiet, partly because the main drive winch is located directly beneath the top of the lift, a location which will normally be relatively far from guest-accessible areas.
Despite having several advantages over a chain lift, It has a significant disadvantage, which is that it must return to the bottom of the lift hill after lifting each train (in contrast to a continuously moving chain lift which does not need any kind of resetting). This limits the usefulness of the cable lift in applications where the cable must travel a long distance and the interval between train departures is short.
Ferris wheel lift
The Ferris wheel lift is a type of lift based on the rotating circular design of a ferris wheel. Created by Premier Rides, it exists on 'Round About' (formerly Maximum RPM) which operated at Freestyle Music Park in Myrtle Beach, South Carolina prior to being dismantled and moved to a park in Vietnam. It uses a Ferris Wheel like motion to lift the cars to the top, as on a Ferris Wheel. The cars are then released onto the track.
The elevator lift is a new technology used to make the ascension of the roller coaster faster and more comfortable due to the fact all riders are doing is moving vertically up. It is used mostly in indoor rollercoasters like Scooby-Doo Spooky Coaster. As of 2015 only 15 operating roller coasters have an elevator lift, and 2 new roller coasters are planned for 2015 that will in some way include an elevator lift. Another roller coaster named Cobra's Curse at Busch Gardens Tampa is planned for 2016.
Tilt lift/thrill lift section
A tilt lift is a new way to elevate coasters. The tilt lift is essentially an elevator lift, but the elevator lift rotates 90 degrees so that the train is now vertical, with the nose of the train facing the ground. This design has not been made yet; the only places where this occurs are in the video games RollerCoaster Tycoon 3 and Coaster Crazy. However, there are coaster designs that use the tilting aspect of this lift already. The first operating Tilt Coaster in the world is Gravity Max! at Discovery World in Taiwan. The coaster was built by Vekoma. In this coaster, after going up a chain hill, the train is held on a horizontal section of track, which then tilts forwards, to become a vertical section, which then leads into a vertical drop accelerated by gravity. The second and third being Flip Coaster in Hefei Wanda Cultural Tourism City, set to open in 2016, however it is believed that these are not built by Vekoma. 
The familiar "click-clack" sound that occurs as roller coaster train ascends the lift hill is not caused by the chain itself. The cause for this noise is actually a safety device used on lift hills -- the anti-rollback device. The anti-rollback device is a standard safety feature, typically consisting of a continuous, saw-toothed, section of metal, forming a linear ratchet.
Roller coaster trains are fitted with anti-rollback "dogs" which are essentially heavy-duty pieces of metal which fall and rest in each groove of the anti-rollback device on the track as the trains ascend the lift-hill. This makes the "clicking" sound and allows the train to go upwards only, effectively preventing the train from rolling back down the hill should it ever encounter a power failure or broken chain.
This feature was derived from the similar feature originally used on the Mauch Chunk Switchback Railway in Pennsylvania, starting in 1846. The two uphill planes that cars were drawn up under the power of a stationary steam engine had two slightly different early forms of this anti-rollback device. The entire concept of the modern roller coaster was also initially inspired by this railroad.
Invented in part By Sir John Robinson of Morton IL