Specifications include, but are not limited to: School Bus Chassis. 1.2. Axles. 1.2.a. The front axle shall be heavy-duty bus type and equipped with oil bath (synthetic lubricant) or unitized wheel bearings. Exception: Type A buses. 1.3. Back Up Alarms. 1.3.b. Variable sound is not permitted. 1.4. Brakes (Air). 1.4.b. Buses using an air-operated braking system shall be equipped with a Wig-Wag warning device and/or devices readily audible, which have a minimum rating of 80 dB and a maximum rating of 85 dB measured at the operator's ear and visible to the operator. The device will give a continuous warning when the air pressure available in the system for braking is 60 pounds per square inch (psi) or less and must remain activated until the system is at or above 60 psi. An illuminated gauge that will indicate to the operator the air pressure in pounds per square inch or the inches of mercury vacuum available for the operation of the brakes shall be provided. An anti-lock braking system (ABS) shall be standard on units with air brakes. 1.4.b.1. Air brakes shall be installed on all chassis. Exception: Type A and less than 35 passenger vehicles.
