1. Field of the Invention.
The present invention relates, in general, to amusement park rides and other implementations in which it is desirable to prevent or control backward rolling of a car or vehicle, and, more particularly, to an anti-roll back assembly for use in such park rides or other implementations that functions to automatically position the anti-roll back (ARB) in a raised or normal operations position in which it is spaced apart from roll back pins or stops while the vehicle or car travels in a desired (or forward) direction and then to automatically position the ARB in a lowered or down position in which it engages a roll back pin or stop (or cross bolt/rail/chain) such that backwards/reverse roll or travel is stopped (or such that a vehicle may engage a chain/pin to be lifted up an inclined portion of the ride's or other implementation's track).
2. Relevant Background.
Many amusement or theme park ride attractions have vehicles or cars for carrying passengers, and a vehicle or car in a ride may be towed up an incline to a high elevation and released to continue throughout the ride path via gravity. The vehicle may be, for example, a roller coaster type car, or a water flume type boat in which the vehicles are pulled up the incline by a moving chain or cable. As a safety precaution, these types of ride attractions uniformly have braking or anti-roll back (ARB) systems to prevent a vehicle from moving in reverse down the incline. The ARB acts to prevent backward or reverse rolling in case the vehicle inadvertently is released from the towing chain or cable before reaching the crest of the incline or if the chain or drive system fails. In other words, an ARB is a unit traditionally found on coasters and similar rides that has two main purposes. The first is to engage with a chain to move a vehicle up a lift or inclined portion of the track. The second is to prevent the vehicle from moving backwards on a lift or inclined portion of the track in case of chain failure.
A common braking or ARB system in these applications uses a pivoting pawl on the bottom of the vehicle. As the vehicle is towed forwardly and upwardly on the incline, the pawl bumps over closely spaced apart stops. If the vehicle begins to move in reverse, the pawl engages the nearest downhill stop, thereby preventing any further reverse movement of the vehicle. As the stops are closely spaced apart, in the event of failure of the towing system, the vehicle can move only a very short distance in reverse such as only a few inches. This type of ARB system accordingly reliably prevents the vehicle from moving down the incline uncontrolled at high speed, potentially colliding with another vehicle. Presently, ARBs or the pawls of ARBs are pulled down (or actuated) by gravity, and the pawls are pivotally hung or supported on pins on the underside of the vehicle or car chassis or frame.
While these ARB systems using a pawl and a series of stops are widely used, they have a number of drawbacks. The vehicles often are traveling at high speeds over the ARB or stop sections of the track (e.g., up inclines that include the stops or ARB pins). The ARBs or ARB pawls are pulled toward the stops/pins by gravity and their front or leading edge contacts all or nearly all of the stops or pins, which produces the clank, clank, clank noise as the vehicle moves along the track. Hence, rides using the conventional, gravity actuated ARBs tend to be very noisy, generating loud clanking sounds, as the metallic pawl bumps over each of the fixed stops. Each impact of the pawl also generates shock and vibration in the vehicle and wear on the pawls and the stops.
Accordingly, a quieter ARB or braking system is desired to reduce noise pollution and preferably such an ARB system could be designed so as to also reduce wear and limit maintenance requirements. Some efforts have been made to provide an ARB that is suspended above the stops or ARB pins while the vehicle is traveling in a forward or desired direction such as up a lift. For example, some rides have been developed that suspend ARBs while the vehicle is traveling up a lift. One design makes use of a magnetic coupler in which a magnet is carried on the vehicle and a secondary wheel rides along a track. When the wheel is engaged the magnetic coupler rotates the ARB upward away from the stops/pins. These designs, however, have typically been limited to use when the vehicle is traveling at very low speeds (such as less than several feet per second) and tend to overheat at higher speeds experienced in normal operations of a coaster or similar vehicle (e.g., a coaster vehicle may travel up inclines at up to 30 feet per second or more).
Other designs have typically utilized mechanical assemblies such as ones with a secondary wheel and linkage that make use of friction or other forces to selectively lift the ARBs. These designs, however, have not been widely adopted because they require significant amounts of maintenance including daily adjustments by ride operators to obtain desired amounts of component interaction or frictional drag for proper operation/lift of the ARBs. Further, these types of drag-based ARB systems often are not useful for rides with higher vehicles speeds that are found in most coaster rides.