Roller Coasters

[TalonRider]

SAFETY DEVICES

Anti-Rollbacks:

That familiar clanking sound associated with most coasters during the lift hill ascent is caused by a safety device patented by the prolific John Miller back in 1910. Chain dogs, also called "hoisting dogs," not only enable the coaster train to climb the lift hill, they also serve as anti-rollback devices. Basically, the device consists so a pivoiting mechanism that latches on the moving chain during the climb up the lift. A second pivoting safety dog works independently by making contact with a series of ratchets located on the track alongside the chain. This acts as a backup safety measure during the lift sequence as well as near the crests of certain hill out on the course. Should the chain break during a lift, or if a train fails to mount a hill during it circuit, the backward motion of the vehicles will be restricted by the anti-rollbacks, securing the cars in place until the situation can be resolved. Though virtually all lift hills use a version of this ratcheting anti-rollback system, not every coaster features them along the circuit.

Brakes

As the roller coaster progressed from the simple switchback- and Scenic Railway -format of the late 1800s to the high-speed wooden and steel coasters we know today, the braking systems devised to slow or stop the trains evolved as well.

Through the mid-1980s, the most common braking systems for wooden coasters were called "skid" or "sled" brakes. These devices involved a series of long, flat parallel bars situated between the running rails. In normal position, these bars were raised so that when the train approached the loading platform, the skid brakes would make contact with brake shoes mounted on the undersides of the cars. The friction created brought the train to a smooth stop, sometimes actually raising it slightly off the rails. Once the train was unloaded and refilled with passengers, the operator lowered the brakes by pulling one or moer long wooden brake handles or levers inside the station area. With brakes released, the train coasted out of the station and began its next run.

Though another braking system know as the "squeeze brake" was developed for use on some wooden coasters built in the mid-twebtuetg century, it was the steel coasters (especially the looping rides that came along in the mid-1970s) that benefited from and perfected this style of brake. Also known as "fin brake," this configuraton features long metal fins hanging beneath the train or attached to the cars' lower sides. When these fins pass through pneumatically controlled brake units between the rail (or on the sides of the track), the fins are caught in a tight clamp, effectively and sometimes abruptly bringing the trains toa screeching halt.

Taken from:

ROLLER COASTERS by Scott Rutherford

Published in 2003 by Lowe & B. Hould Publishers

Previously published in 2000 by MBI Publishing Company.