| 摘要 |
A vehicle air brake system (180) includes a novel three chamber brake actuator (182) having a service brake, chamber (8), a spring brake chamber (10) and a supplemental chamber (212). A conventional modulated spring brake control valve (78) is used to supply pressurized air to the spring brake chamber. The service brake chamber is supplied with air through the outlet of a conventional service brake application valve (68). The force applied to the actuator piston (198) can be changed to a lower force for parking and a higher force for emergencies according to the pressure applied to the spring brake and supplemental chambers. |
