Bumper cars or dodgems are the generic names for a type of flat amusement ride consisting of multiple small electrically powered cars which draw power from the floor and/or ceiling, and which are turned on and off remotely by an operator. Bumper cars were not intended to be bumped, hence the original name "Dodgem." They are also known as bumping cars, dodging cars and dashing cars. The first patent for bumper cars was filed in 1921 The cars are commonly powered by one of three methods. The oldest and most common method, the Over Head System (OHS), uses a conductive floor and ceiling with opposing power polarities. Contacts under the vehicle touch the floor while a pole-mounted contact shoe touches the ceiling, forming a complete circuit. A newer method, the Floor Pick-Up (FPU) system, uses alternating strips of metal across the floor separated by insulating spacers, and no ceiling grid. The strips carry the supply current, and the cars are large enough so that the vehicle covers at least two strips at all times. An array of brushes under each car makes random contact with the strips, and the voltage polarity on each contact is arranged to always provide a correct and complete circuit to operate the vehicle. A third method is used on Quantum-class cruise ships, where bumper cars run on electric batteries. This avoids the conductive floor/ceiling of the traditional bumper car setup, allowing the SeaPlex venue to be convertible from a bumper-car ride to a multipurpose gym (basketball court). The disadvantage is that these ships' bumper cars take several hours to recharge. The metal floor is usually set up as a rectangular or oval track, and graphite is sprinkled on the floor to decrease friction. A rubber bumper surrounds each vehicle, and drivers either ram or dodge each other as they travel. The controls are usually an accelerator and a steering wheel. The cars can be made to go backwards by turning the steering wheel far enough in either direction
