| 摘要 |
A friction/dynamic brake blending valve device is provided for a railway vehicle brake control system, in which a torque motor is arranged with opposing field windings so that its output shaft reflects the difference between an electric brake control current supplying one winding and an electrical signal representing the effective dynamic brake effort supplying the other winding. The output shaft acts through a lever arrangement to drive a pneumatic regulating valve which provides the necessary friction brake pressure to supplement the dynamic brake an amount sufficient to produce vehicle retardation, by the combined dynamic and friction brake efforts, corresponding to the brake control signal. The ratio of the output shaft torque to the pneumatic brake pressure is adjustable, in accordance with the vehicle load condition, through a movable fulcrum interposed between the lever arrangement connecting the output shaft and pneumatic regulating valve. Auxiliary pneumatic control means is provided to operate the pneumatic regulating valve through the lever arrangement independent of the torque motor to produce friction brake in the event electric failure renders the torque motor ineffective. |
