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, necessary in the frequent
pile-ups that occur.
Power source , 1940 The cars are commonly powered by one of three methods. The oldest and most common method, the
overhead 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. ==Bumping==