Universal pneumatic brake control unit

摘要

A universal unit controls the brakes of a truck of a rail vehicle. The unit includes a service valve, an emergency valve, a variable load relay valve, a release valve, a local control means, a solenoid driver means and a brake assurance means. The service valve when opened provides a first control pressure. The emergency valve when opened provides a second control pressure. In response the control pressures, the variable valve provides to the brake cylinder a load compensated pressure proportional to air spring pressure. The brakes then apply to the wheels of the truck a force that accounts for the load borne by the rail vehicle. The release valve when opened prevents the variable valve from providing the load compensated pressure. The local control means controls the control pressures according to a brake force command signal and a control pressure feedback signal. The solenoid means operates the valves in response to valve command signals received from the local control means. The brake assurance means operates in a standby mode in which the local control means controls the release and emergency valves via the solenoid means or in an intervention mode in which it does not thereby assuring that the release and emergency valves open. This enables the variable valve to provide the brake cylinder with the load compensated pressure and therefore apply the brakes. The brake assurance means assumes the intervention mode in response to a loss of power or to a predetermined set of conditions. <IMAGE>