Brakes (rollercoaster)

Rollercoasters use brakes to slow down, or completely stop the train. Rollercoaster brakes can come in the form of magnetic and physical brakes, manual and automatic brakes, brakes that are on the train, and brakes that are on the track. Brakes have existed for as long as rollercoasters have, but they have evolved over time, going from manual skid brakes, to the highly technical magnetic and friction brakes of today.

Contrary to popular belief, most rollercoasters do not feature brakes on the train. Instead, rollercoasters generally feature brake runs. As a rollercoaster enters a brake run, the brakes will engage, bringing the rollercoaster to an appropriate speed. Generally on modern steel rollercoasters, this brake run will often consist of Magnetic brakes to slow the train, friction brakes to stop the train, and drive-tyres to push into the station or the next part of the circuit. There are however, some anomalies, such as the Matterhorn and other early steel coasters still using skid brakes, and some brake runs not using magnetic brakes, such as Nemesis, or their brake run not needing drive-tyres due to it being on a downwards slope (such as on Shambhala).

On most roller coasters, the brakes are controlled by a computer system. Some older coasters have brakemen or manually operated friction or skid brakes, some with a pneumatic assist. These are either engaged at the control panel or operated by pulling or pushing large levers in the station.

Trim and Block Brakes

Trim brakes

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

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. 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.

Types of brakes

Roller coasters utilize a variety of braking methods that have evolved over time.

Skid brakes are common on older wooden roller coasters, such as Thunderbolt at Kennywood

Skid brakes

Skid brakes involve a long piece of material, often ceramic-covered, that is situated in the middle of the track parallel to the rails. When the brake is engaged, the skid raises and causes friction against the underside of the train, reducing its speed. They can be used to slow or stop the train. Skid brakes were one of the first advancements in roller coaster braking and are typically found on older wooden coasters, such as Leap the Dips, the world's oldest roller coaster still in operation.

Side mounted brakes are common on Schwarzkopf roller coasters, such as Scorpion at Busch Gardens Tampa Bay

Friction brakes on Speed: No Limits at Oakwood Theme Park

Friction brakes

Friction brakes, commonly called fin brakes, involve a computer-controlled clamping system that squeeze metal fins attached to either the side or belly of the train. Friction brakes can be used to slow or stop the train and are the most common form of brakes found on modern roller coasters. They can involve thick metal box beams or thin metal plates. They slide between pairs of friction pads similar to automotive brake pads.

Friction brakes are designed to be fail-safe, allowing them to engage even when there is a loss of power. They are also constructed with a certain measure of redundancy, incorporating extra sets of brakes in the event that one set fails. Opening is done by a bellows type of air-operated actuator, with each set of brakes fitted with its own air supply system that is controlled by supply valves that open and release the brake when it is safe to do so. A heavy spring usually made of steel is used to hold the brake closed when engaged.

Magnetic brakes

See also: Linear eddy current brake

Instead of relying on friction, which can often be affected by weather conditions such as rain, magnetic brakes apply resistance through magnetism without making direct contact with the train. They are made up of one or two rows of neodymium magnets. When a metal fin made of copper or a copper-aluminum alloy passes between the rows of magnets, eddy currents are generated in the fin, creating a magnetic force that opposes the fin's motion. The resultant braking force is directly proportional to the speed at which the fin is moving through the brake element.

Magnetic brakes can be found in two configurations:

• The brake elements are mounted to the track or alongside the track and the fins are mounted to the underside or sides of the train. This configuration looks similar to friction brakes.
• The fins are mounted to the track and the brake elements are mounted to the underside of the train. This configuration can be found on Intamin Accelerator Coasters.

Magnetic brakes are silent and provide a smoother riding experience than friction brakes, gradually increasing the braking power so that the people on the ride do not experience rapid changes in deceleration. Intamin began incorporating them with their Accelerator Coaster models, as well as Bolliger & Mabillard beginning in 2004 with their installation of Silver Bullet, the first inverted coaster to feature magnetic brakes. There are also third-party companies, such as Magnetar Technologies Corp., which provide a service to retrofit existing coasters with magnetic braking technology to increase safety, improve rider comfort, and lower maintenance costs and labor.

Magnetic brakes on Speed, located before the friction brakes. These track-mounted fins can be retracted to allow the train to pass without slowing it down.

A disadvantage of magnetic braking is that the eddy force is not usually stable enough to hold a train completely still, and as such cannot be used as block brakes. Magnetic brakes are often complemented by an additional set of friction brakes or "kicker wheels", rubber tires that make contact with the train and effectively park it. Another disadvantage is that they cannot be conventionally disengaged like other types of brakes. Instead, the fins or magnets must be retracted so that the fins no longer pass between the magnets. Accelerator Coasters, for example, have a series of magnetic brake fins located on the launch track. Prior to the train's launch, the brakes are retracted out of the way to allow the train to reach its maximum speed. After launch, the brake fins are raised back in position to stop the train in the event of a rollback. An example of this can be found on Kingda Ka at Six Flags Great Adventure.

Brake Men

While skid brakes already existed by the time Scenic Railway had been conceived, LaMarcus Adna Thompson decided against using these brakes for his Scenic Railway roller coasters, and instead opted for using a brakeman system in a similar to manner to those used on gravity trains. The brakeman would sit in the center of the train and pull a lever to apply a brake and slow down the train. Over thirty Scenic Railways were constructed, but only a small number remain in operation.