Block brakes

A brake run on a roller coaster is any section of track meant to slow or stop a roller coaster train. Brake runs may be located anywhere along the circuit of a coaster and may be designed to bring the train to a complete halt or to simply adjust the train's speed. Contrary to some belief, the vast majority of roller coasters do not have any form of braking on the train itself, but rather forms of braking that exist on track sections. One notable exception is the scenic railway roller coaster, which relies on an operator to manually control the speed of the train.

On most roller coasters, the brakes are controlled by a computer system, but some older wooden roller coasters have manually operated brakes. These are controlled by large levers operated by the ride operators.

Trim brakes are sections of brakes which are intended to adjust a train's speed during its course rather than bring the train to a complete stop. They may be engineered into a ride at its design stages at certain anticipated troubled spots, or later retrofitted once it is discovered that trains traverse certain areas at higher-than-anticipated speeds. Trim brakes are often either added for safety reasons, to lower g-forces in certain areas, or for maintenance/mechanical reasons, to lower the cost of wear-and-tear damage (especially on wooden roller coasters) caused by the trains traveling at faster than normal speeds. Usually, a proximity sensor precedes the trim brake in order to identify the current speed of the passing train. From this, the trim will then grab the train's brake fins to reduce the train's speed to that set by the control system.

Block brakes are sections of brakes located on any roller coaster wherever more than one train is intended to run. They act as virtual barriers between the trains running on the roller coaster, preventing collisions should one train stop along the course for any reason. Because of this, block brakes must be capable of completely stopping the train (should a vehicle preceding the block stop) and starting a train (after it has been stopped). Block brake sections usually start the train again either by using a slight downward slope to let gravity take its course, or by using drive tires to push the train out of the block. Like trim brakes, block brakes can also be used to control the speed of the train. These are usually known as mid-course brake runs. An example of a mid-course brake run is on Titan at Six Flags Over Texas, which consists of such a brake run (which slows the train down drastically, almost to the point of stopping) due to the severe G-forces in its downward 540-degree helix following the brake run. Mid-course brake runs give more time for another train to be loaded. Often times, mid-course brake runs give so much time that another train can be fitted onto the track without the worry of bumping.

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Wikipedia