Xcelerator

Xcelerator is a steel launched roller coaster at Knott's Berry Farm in Buena Park, California. The ride was Intamin's first hydraulically launched coaster, whilst also the fourth Intamin installation at Knott's, alongside The Sky Cabin, Bigfoot Rapids, and Perilous Plunge (removed in 2012).

The ride
Xcelerator's powerful hydraulic catapult motor accelerates the train to 82 mi/h in 2.3 seconds (about 1.62 g). It only uses 157 ft of track to launch the train. The twin hydraulic catapult motor achieves a maximum of 10500 hp each while accelerating the train. Xcelerator's hydraulic motor system has the mechanical capability of accelerating vehicles to a speed of 117 mi/h or more, though it only needs to hit 82. In order for a train to launch, it must "drift" back to "hook" into the catch car. Twenty-four volts are used to demagnetize a pin underneath the third car, causing it to drop. At the same time, two bellows actuators fill up with air, causing the two drive tires holding the train in place, at the train's rear, to retract. The brakes will lower while the train rolls back to hook, and the pin will then hook into the catch car—which is over 7 ft long. Once connected, the motor will pull the catch car over nylon runners and launch the train. In order to stop the catch car, it passes over its own set of magnetic brakes. If the train is lightly loaded, the motor has to work harder to attain launch speed. Often the catch car may overshoot its ending position and down itself if it cannot attain the speed within parameters. The train must also clear the launch track within three seconds, or the ride will down itself and produce a shortshot. From the time the launch begins, the train has 8.25 seconds to pass over a proximity switch (Hall effect sensor) near the bottom the first valley, thus clearing the starting block. If the train does not pass over the switch within the given time frame, the ride will down itself.

After launch, the train then crests a vertical 205 ft top hat element(unlike rides like Stealth at Thorpe Park as its ascent is not vertical), then soars through a 110 ft and 95 ft over banked turns, and glides to a smooth stop over mounted magnetic brakes. The magnetic braking system consists of mounted magnetic clippers on the trains themselves and copper alloy fins mounted onto the track. The alloy fins on the launch section retract during the launching procedure so as to not interfere with the train. To slow the train in case of a rollback, they raise section by section after the train has passed them. The brake fins on the brake run are stationary and cannot be lowered. Vehicles are traveling at approximately 67 mi/h when entering the brake run.

The trains
The ride has two trains: Purple Train and Red Train. The trains themselves have spring-loaded wheel assemblies and are standard Intamin trains with specially crafted shells to make them look like 1957 Chevrolet Bel Air convertibles. Xcelerator's red train was originally a different color. When Xcelerator first opened, the red train was all yellow with red flames along the side. During one of the ride's rehabs, the yellow-colored train was repainted red and given orange flames, closely mimicking the style of the Purple Train. Now, after the accident, the Red Train is now Red with Patriotic flames running along the front and sides of the train. Each train is 5 cars long and holds 20 passengers. A maximum of 2 trains may be operated at any given time. During the slow season, it's not uncommon to see only one train in use; but during the summer and peak season, both trains are normally used. For the 2011 season, the trains were re-painted to an American flag style.

Restraints
Xcelerator's trains use hydraulically operated T-Bar lapbar restraints. These restraints appeared on Intamin's earlier accelerator coasters, but over-the-shoulder restraints are now the normal type used on any new accelerator coaster due to safety concerns. Xcelerator also had special meters installed on its restraints. The meter must show all green in order for a guest to ride. If the meter shows red, the guest cannot ride the attraction. Eventually, the meter system was removed and the park now uses black lines etched on the side of each restraint. The black line must pass a certain part of the seat frame in order for the guest to ride. The attraction also has seatbelts, which must be buckled before an operator pulls down on the lapbar. Failure to do so slows the load time of the attraction considerably. Another contributing factor to a guest not being able to ride, involving the seat belts, is that at least one inch of slack must be able to pulled out from buckle. If no slack of the belt shows, the guest is too large to ride, even though the seat belt may be completely buckled.

Rollbacks


Occasionally, a train will not attain enough speed to make it over the initial 205 ft top hat element. Instead, the train will partially ascend the tower, stall, and then roll back into magnetic brake fins situated on the launch track. This is known as a rollback, and is part of the normal design of the ride. A rollback can cause Xcelerator to close for an indefinite amount of time while the ride is reset and a sufficient number of test launches are performed. Rain, weight, frequency of launching, outside temperature, and overheating can contribute to a rollback.

Weather
Xcelerator will not operate in the rain—not even a drizzle. This is to prevent rollbacks due to hydroplaning on the launch track. The track usually needs to dry until maintenance has cleared it to operate again before the first test launch is made. This is to reduce the chance of a rollback.

Progression to taller and faster, inversion rides
Xcelerator laid the groundwork for taller and faster rides such as Top Thrill Dragster at Cedar Point and Kingda Ka at Six Flags Great Adventure, coasters both passing the 400 ft mark and 100 mi/h mark. Xcelerator also laid the groundwork for rides featuring inversions, such as Storm Runner at Hersheypark, which has banked inversions, and Kanonen at Liseberg, which features a vertical loop.

While successful in doing this, modifications were made to the larger models before being built. Storm Runner, Kingda Ka, and Top Thrill Dragster use a dual loading stations to speed up dispatching times, as well as larger, more-powerful motors. Kingda Ka also has two fewer seats per train than Storm Runner.

Lower-powered coasters have been built as well, such as Rita at Alton Towers.

Incidents

 * On September 16, 2009 a cable snapped during the launch of the ride, sending pieces of debris flying and lacerating the left leg of 12-year-old Kyle Wheeler. Both Kyle and another male rider, who complained of back pain, were sent to the hospital. The man was released, but Kyle Wheeler has undergone multiple surgeries to repair the damaged muscle tissue in his leg. Russel Wheeler, the father of Kyle, was sitting beside Kyle when the cable snapped. The Wheeler family won an undisclosed amount of money in a lawsuit against the park. The ride has since been reopened.
 * On August 7, 2013 a cable snapped during the launch of the ride, which sent debris flying in the air. Nobody was hurt. The ride was reopened about a month later.

Television appearances

 * Xcelerator appeared on Smash Lab in an episode about Magnetic Braking
 * Xcelerator appeared in the movie Knocked Up
 * Xcelerator was the last level on the Cartoon Network TV show BrainRush.
 * Xcelerator was featured on an episode of Paris Hilton's My New BFF.
 * Xcelerator was shown in the E! reality show, The Girls Next Door
 * Xcelerator appeared in an episode of the DIY Network's show "Man Caves", in which reality TV star Burt the Conqueror rode the coaster